Bump version: 1.15.7 → 1.16.0

Also, fix a few pylint issues.

.bumpversion.cfg

@@ -0,0 +1,6 @@
+[bumpversion]
+commit = True
+tag = True
+current_version = 1.16.0
+
+[bumpversion:file:pyproject.toml]

.github/workflows/build.yml

@@ -0,0 +1,36 @@
+name: build
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12", "3.13"]
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v4
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install
+      run: |
+        python -m pip install --upgrade pip setuptools
+        pip install pytest pytest-cov mock pycodestyle coverage pylint
+        pip install -e .
+
+    - name: Lint
+      run: |
+        pycodestyle amodem/ scripts/
+        pylint --extension-pkg-whitelist=numpy --reports=no amodem --rcfile .pylintrc
+
+    - name: Test with pytest
+      run: |
+        pytest -v --cov=amodem

.gitignore

@@ -1,4 +1,5 @@
 *~
+\#*\#
 *.out
 *.pyc
 *.sublime-*
@@ -23,3 +24,6 @@ htmlcov
 *_ext.so
 /.tox
 /dist
+/deb_dist
+*.html
+.pytest_cache/

.pylintrc

@@ -0,0 +1,2 @@
+[MESSAGES CONTROL]
+disable=invalid-name, missing-docstring, too-many-instance-attributes, too-few-public-methods, logging-format-interpolation, consider-using-with, redefined-outer-name

.travis.yml

@@ -1,20 +0,0 @@
-sudo: false
-language: python
-python:
-  - "2.6"
-  - "2.7"
-  - "3.2"
-  - "3.3"
-  - "3.4"
-
-install:
-  - pip install .
-  - pip install coveralls pep8 mock
-
-script:
-  - pep8 amodem/ scripts/ tests/ amodem-cli
-  - cd tests
-  - coverage run --source=amodem -m py.test
-
-after_success:
-  - coveralls

LICENSE

@@ -1,6 +1,6 @@
 amodem -- Audio Modem Communication Library
 
-Copyright (C) 2014, Roman Zeyde.
+Copyright (C) 2014, Roman Zeyde, Google Inc.
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -1,185 +0,0 @@
-# Audio Modem Communication Library
-
-[![Build Status](https://travis-ci.org/romanz/amodem.svg?branch=master)](https://travis-ci.org/romanz/amodem)
-[![Coverage Status](https://coveralls.io/repos/romanz/amodem/badge.png?branch=master)](https://coveralls.io/r/romanz/amodem?branch=master)
-[![Code Health](https://landscape.io/github/romanz/amodem/master/landscape.svg)](https://landscape.io/github/romanz/amodem/master)
-[![Supported Python versions](https://pypip.in/py_versions/amodem/badge.svg)](https://pypi.python.org/pypi/amodem/)
-[![License](https://pypip.in/license/amodem/badge.svg)](https://pypi.python.org/pypi/amodem/)
-
-# Description
-
-This program can be used to transmit a specified file between 2 computers, using
-a simple audio cable (for better SNR and higher speeds) or a simple headset,
-allowing true air-gapped communication (via a speaker and a microphone).
-
-The sender modulates an input binary data file into an 32kHz audio,
-which is played to the sound card.
-
-The receiver side records the transmitted audio,
-which is demodulated concurrently into an output binary data file.
-
-The process requires a single manual calibration step: the transmitter has to
-find maximal output volume for its sound card, which will not saturate the
-receiving microphone.
-
-The modem is using OFDM over an audio cable with the following parameters:
-
-- Sampling rate: 32 kHz
-- Baud rate: 1 kHz
-- Symbol modulation: BPSK, 4-PSK, 16-QAM ,64-QAM
-- Carriers: 2-11 kHz
-
-This way, modem may achieve 60kbps bitrate = 7.5 kB/s.
-
-A simple CRC-32 checksum is used for data integrity verification
-on each 250 byte data frame.
-
-
-# Installation
-
-Make sure that `numpy` and `PortAudio v19` packages are installed (on Debian):
-
-    $ sudo apt-get install python-numpy portaudio19-dev
-
-Clone and install latest version:
-
-    $ git clone https://github.com/romanz/amodem.git
-    $ pip install --user -e amodem
-
-For graphs and visualization (optional), install `matplotlib` Python package.
-
-For validation, run:
-
-    $ export BITRATE=16  # explicitly select high MODEM bit rate (assuming good SNR).
-    $ amodem-cli -h
-    usage: amodem-cli [-h] {send,recv} ...
-
-    Audio OFDM MODEM: 48.0 kb/s (64-QAM x 8 carriers) Fs=32.0 kHz
-
-    positional arguments:
-      {send,recv}
-        send         modulate binary data into audio signal.
-        recv         demodulate audio signal into binary data.
-
-    optional arguments:
-      -h, --help     show this help message and exit
-
-
-# Calibration
-
-Connect the audio cable between the sender and the receiver, and run the
-following scripts:
-
-- On the sender's side:
-```
-~/sender $ export BITRATE=48  # explicitly select high MODEM bit rate (assuming good SNR).
-~/sender $ amodem-cli send --calibrate
-```
-
-- On the receiver's side:
-```
-~/receiver $ export BITRATE=48  # explicitly select high MODEM bit rate (assuming good SNR).
-~/receiver $ amodem-cli recv --calibrate
-```
-
-If BITRATE is not set, the MODEM will use 1 kbps settings (single frequency with BPSK modulation).
-
-Change the sender computer's output audio level, until
-all frequencies are received well:
-```
-  1000 Hz: good signal
-  2000 Hz: good signal
-  3000 Hz: good signal
-  4000 Hz: good signal
-  5000 Hz: good signal
-  6000 Hz: good signal
-  7000 Hz: good signal
-  8000 Hz: good signal
-```
-
-If the signal is "too weak", increase the sender's output audio level.
-
-If the signal is "too strong", decrease the sender's output audio level.
-
-If the signal is "too noisy", the SNR is probably too low: decrease the
-background noise or increase the signal (without causing saturation).
-
-# Usage
-
-- Prepare the sender (generate a random binary data file to be sent):
-
-```
-~/sender $ dd if=/dev/urandom of=data.tx bs=16kB count=1 status=none
-~/sender $ sha256sum data.tx
-008df57d4f3ed6e7a25d25afd57d04fc73140e8df604685bd34fcab58f5ddc01  data.tx
-```
-
-- Start the receiver (will wait for the sender to start):
-```
-~/receiver $ amodem-cli recv -vv -i data.rx
-```
-
-- Start the sender (will modulate the data and start the transmission):
-```
-~/sender $ amodem-cli send -vv -o data.tx
-```
-
-- A similar log should be emitted by the sender:
-```
-2014-10-23 09:46:36,116 DEBUG      MODEM settings: {'F0': 1000.0, 'Nfreq': 8, 'Fs': 32000.0, 'Npoints': 64, 'Tsym': 0.001}              amodem:126
-2014-10-23 09:46:36,116 DEBUG      Running: ['aplay', '-', '-q', '-f', 'S16_LE', '-c', '1', '-r', '32000']                              wave.py:20
-2014-10-23 09:46:36,665 INFO       Sending 2.150 seconds of training audio                                                              send.py:69
-2014-10-23 09:46:36,665 INFO       Starting modulation: <48.000 kbps, 64-QAM, 8 carriers>                                               send.py:74
-2014-10-23 09:46:37,735 DEBUG      Sent      6.0 kB                                                                                     send.py:56
-2014-10-23 09:46:38,794 DEBUG      Sent     12.0 kB                                                                                     send.py:56
-2014-10-23 09:46:39,440 INFO       Sent 16.384 kB @ 2.754 seconds                                                                       send.py:79
-```
-
-- A similar log should be emitted by the receiver:
-```
-2014-10-23 09:46:36,116 DEBUG      MODEM settings: {'F0': 1000.0, 'Nfreq': 8, 'Fs': 32000.0, 'Npoints': 64, 'Tsym': 0.001}              amodem:126
-2014-10-23 09:46:36,238 DEBUG      Running: ['arecord', '-', '-q', '-f', 'S16_LE', '-c', '1', '-r', '32000']                            wave.py:20
-2014-10-23 09:46:36,408 DEBUG      Skipping 0.128 seconds                                                                               recv.py:275
-2014-10-23 09:46:36,409 INFO       Waiting for carrier tone: 1.0 kHz                                                                    recv.py:282
-2014-10-23 09:46:37,657 INFO       Carrier detected at ~886.0 ms @ 1.0 kHz: coherence=99.996%, amplitude=0.475                          recv.py:40
-2014-10-23 09:46:37,657 DEBUG      Buffered 1000 ms of audio                                                                            recv.py:64
-2014-10-23 09:46:37,660 DEBUG      Carrier starts at 9.531 ms                                                                           recv.py:73
-2014-10-23 09:46:38,119 DEBUG      Prefix OK                                                                                            recv.py:108
-2014-10-23 09:46:38,153 DEBUG      Current phase on carrier: -0.497                                                                     recv.py:121
-2014-10-23 09:46:38,153 DEBUG      Frequency error: 0.02 ppm                                                                            recv.py:123
-2014-10-23 09:46:38,682 DEBUG        1.0 kHz: SNR = 34.20 dB                                                                            recv.py:165
-2014-10-23 09:46:38,715 DEBUG        2.0 kHz: SNR = 35.05 dB                                                                            recv.py:165
-2014-10-23 09:46:38,766 DEBUG        3.0 kHz: SNR = 35.52 dB                                                                            recv.py:165
-2014-10-23 09:46:38,803 DEBUG        4.0 kHz: SNR = 35.65 dB                                                                            recv.py:165
-2014-10-23 09:46:38,837 DEBUG        5.0 kHz: SNR = 35.03 dB                                                                            recv.py:165
-2014-10-23 09:46:38,869 DEBUG        6.0 kHz: SNR = 35.05 dB                                                                            recv.py:165
-2014-10-23 09:46:38,907 DEBUG        7.0 kHz: SNR = 34.80 dB                                                                            recv.py:165
-2014-10-23 09:46:38,943 DEBUG        8.0 kHz: SNR = 33.74 dB                                                                            recv.py:165
-2014-10-23 09:46:38,977 INFO       Starting demodulation: <48.000 kbps, 64-QAM, 8 carriers>                                             recv.py:197
-2014-10-23 09:46:39,619 DEBUG      Got       6.0 kB, realtime:  64.18%, drift: +0.02 ppm                                                recv.py:215
-2014-10-23 09:46:40,538 DEBUG      Got      12.0 kB, realtime:  78.03%, drift: +0.02 ppm                                                recv.py:215
-2014-10-23 09:46:41,306 DEBUG      EOF frame detected                                                                                   framing.py:60
-2014-10-23 09:46:41,306 DEBUG      Demodulated 16.520 kB @ 2.329 seconds (84.6% realtime)                                               recv.py:244
-2014-10-23 09:46:41,306 INFO       Received 16.384 kB @ 2.329 seconds = 7.034 kB/s                                                      recv.py:247
-```
-
-- After the receiver has finished, verify the received file's hash:
-```
-~/receiver $ sha256sum data.rx
-008df57d4f3ed6e7a25d25afd57d04fc73140e8df604685bd34fcab58f5ddc01  data.rx
-```
-
-# Visualization
-Make sure that `matplotlib` package is installed, and run (at the receiver side):
-
-```
- ~/receiver $ amodem-cli recv --plot -o data.rx
-```
-
-
-# Donations
-
-Want to donate? Feel free.
-Send to [1C1snTrkHAHM5XnnfuAtiTBaA11HBxjJyv](https://blockchain.info/address/1C1snTrkHAHM5XnnfuAtiTBaA11HBxjJyv).
-
-Thanks :)

README.rst

@@ -0,0 +1,248 @@
+Audio Modem Communication Library
+=================================
+
+.. image:: https://img.shields.io/pypi/pyversions/amodem.svg
+    :target: https://pypi.python.org/pypi/amodem/
+    :alt: Python Versions
+.. image:: https://img.shields.io/pypi/l/amodem.svg
+    :target: https://pypi.python.org/pypi/amodem/
+    :alt: License
+.. image:: https://img.shields.io/pypi/v/amodem.svg
+    :target: https://pypi.python.org/pypi/amodem/
+    :alt: Package Version
+.. image:: https://img.shields.io/pypi/status/amodem.svg
+    :target: https://pypi.python.org/pypi/amodem/
+    :alt: Development Status
+
+
+Description
+-----------
+
+This program can transmit a file between 2 computers, using a simple headset,
+allowing true air-gapped communication (via a speaker and a microphone),
+or an audio cable (for higher transmission speed).
+
+The sender modulates the input data into an audio signal,
+which is played to the sound card.
+
+The receiver records the audio, and demodulates it back to the original data.
+
+The process requires a single manual calibration step: the transmitter has to
+find the optimal output volume for its sound card, which will not saturate the
+receiving microphone and provide good enough Signal-to-Noise ratio
+for the demodulation to succeed.
+
+HackerNews discussion: https://news.ycombinator.com/item?id=17333257
+
+Technical Details
+-----------------
+
+The modem is using OFDM over an audio cable with the following parameters:
+
+- Sampling rate: 8/16/32 kHz
+- Baud rate: 1 kHz
+- Symbol modulation: BPSK, 4-PSK, 16-QAM, 64-QAM, 256-QAM
+- Carriers: 2-11 kHz (up to ten carriers)
+
+This way, modem may achieve 80kbps bitrate = 10 kB/s (for best SNR).
+
+A simple CRC-32 checksum is used for data integrity verification
+on each 250 byte data frame.
+
+
+Installation
+------------
+
+Make sure that all the required packages are installed (on Debian)::
+
+    $ sudo apt-get install python-numpy python-pip portaudio19-dev git
+
+Get the latest released version from PyPI::
+
+    $ pip install --user amodem
+
+Or, try the latest (unstable) development version from GitHub::
+
+    $ git clone https://github.com/romanz/amodem.git
+    $ cd amodem
+    $ pip install --user -e .
+
+For graphs and visualization (optional), install `matplotlib` Python package.
+
+For validation, run::
+
+    $ export BITRATE=48  # explicitly select high MODEM bit rate (assuming good SNR).
+    $ amodem -h
+    usage: amodem [-h] {send,recv} ...
+
+    Audio OFDM MODEM: 48.0 kb/s (64-QAM x 8 carriers) Fs=32.0 kHz
+
+    positional arguments:
+      {send,recv}
+        send         modulate binary data into audio signal.
+        recv         demodulate audio signal into binary data.
+
+    optional arguments:
+      -h, --help     show this help message and exit
+
+On, Windows you may download the `portaudio` library from `MinGW <https://packages.msys2.org/base/mingw-w64-portaudio>`_.
+Then, you should specify the DLL using the following command-line flag::
+
+    -l AUDIO_LIBRARY, --audio-library AUDIO_LIBRARY
+                        File name of PortAudio shared library.
+
+
+Calibration
+-----------
+
+Connect the audio cable between the sender and the receiver, and run the
+following scripts:
+
+On the sender's side::
+
+    ~/sender $ export BITRATE=48  # explicitly select high MODEM bit rate (assuming good SNR).
+    ~/sender $ amodem send --calibrate
+
+On the receiver's side::
+
+    ~/receiver $ export BITRATE=48  # explicitly select high MODEM bit rate (assuming good SNR).
+    ~/receiver $ amodem recv --calibrate
+
+If BITRATE is not set, the MODEM will use 1 kbps settings (single frequency with BPSK modulation).
+
+Change the sender computer's output audio level, until
+all frequencies are received well::
+
+  3000 Hz: good signal
+  4000 Hz: good signal
+  5000 Hz: good signal
+  6000 Hz: good signal
+  7000 Hz: good signal
+  8000 Hz: good signal
+  9000 Hz: good signal
+ 10000 Hz: good signal
+
+
+If the signal is "too weak", increase the sender's output audio level.
+
+If the signal is "too strong", decrease the sender's output audio level.
+
+If the signal is "too noisy", it may be that the noise level is too high
+or that the analog signal is being distorted.
+Please run the following command during the calibration session,
+and send me the resulting ``audio.raw`` file for debugging::
+
+    ~/receiver $ arecord --format=S16_LE --channels=1 --rate=32000 audio.raw
+
+You can see a screencast of the `calibration process <https://asciinema.org/a/25065?autoplay=1>`_.
+
+Usage
+-----
+
+Prepare the sender (generate a random binary data file to be sent)::
+
+    ~/sender $ dd if=/dev/urandom of=data.tx bs=60KB count=1 status=none
+    ~/sender $ sha256sum data.tx
+    008df57d4f3ed6e7a25d25afd57d04fc73140e8df604685bd34fcab58f5ddc01  data.tx
+
+Start the receiver (will wait for the sender to start)::
+
+  ~/receiver $ amodem recv -vv -o data.rx
+
+Start the sender (will modulate the data and start the transmission)::
+
+  ~/sender $ amodem send -vv -i data.tx
+
+A similar log should be emitted by the sender::
+
+    2015-02-06 18:12:46,222 DEBUG      Audio OFDM MODEM: 48.0 kb/s (64-QAM x 8 carriers) Fs=32.0 kHz
+    2015-02-06 18:12:46,222 INFO       PortAudio V19-devel (built Feb 25 2014 21:09:53) loaded
+    2015-02-06 18:12:48,297 INFO       Sending 2.150 seconds of training audio
+    2015-02-06 18:12:48,297 INFO       Starting modulation
+    2015-02-06 18:12:49,303 DEBUG      Sent      6.000 kB
+    2015-02-06 18:12:50,296 DEBUG      Sent     12.000 kB
+    2015-02-06 18:12:51,312 DEBUG      Sent     18.000 kB
+    2015-02-06 18:12:52,290 DEBUG      Sent     24.000 kB
+    2015-02-06 18:12:53,299 DEBUG      Sent     30.000 kB
+    2015-02-06 18:12:54,299 DEBUG      Sent     36.000 kB
+    2015-02-06 18:12:55,306 DEBUG      Sent     42.000 kB
+    2015-02-06 18:12:56,296 DEBUG      Sent     48.000 kB
+    2015-02-06 18:12:57,311 DEBUG      Sent     54.000 kB
+    2015-02-06 18:12:58,293 DEBUG      Sent     60.000 kB
+    2015-02-06 18:12:58,514 INFO       Sent 60.000 kB @ 10.201 seconds
+    2015-02-06 18:12:59,506 DEBUG      Closing input and output
+
+A similar log should be emitted by the receiver::
+
+    2015-02-06 18:12:44,848 DEBUG      Audio OFDM MODEM: 48.0 kb/s (64-QAM x 8 carriers) Fs=32.0 kHz
+    2015-02-06 18:12:44,849 INFO       PortAudio V19-devel (built Feb 25 2014 21:09:53) loaded
+    2015-02-06 18:12:44,929 DEBUG      AsyncReader thread started
+    2015-02-06 18:12:44,930 DEBUG      Skipping 0.100 seconds
+    2015-02-06 18:12:45,141 INFO       Waiting for carrier tone: 3.0 kHz
+    2015-02-06 18:12:47,846 INFO       Carrier detected at ~2265.0 ms @ 3.0 kHz
+    2015-02-06 18:12:47,846 DEBUG      Buffered 1000 ms of audio
+    2015-02-06 18:12:48,025 DEBUG      Carrier starts at 2264.000 ms
+    2015-02-06 18:12:48,029 DEBUG      Carrier symbols amplitude : 0.573
+    2015-02-06 18:12:48,030 DEBUG      Current phase on carrier: 0.061
+    2015-02-06 18:12:48,030 DEBUG      Frequency error: -0.009 ppm
+    2015-02-06 18:12:48,030 DEBUG      Frequency correction: 0.009 ppm
+    2015-02-06 18:12:48,030 DEBUG      Gain correction: 1.746
+    2015-02-06 18:12:48,198 DEBUG      Prefix OK
+    2015-02-06 18:12:48,866 DEBUG        3.0 kHz: SNR = 34.82 dB
+    2015-02-06 18:12:48,866 DEBUG        4.0 kHz: SNR = 36.39 dB
+    2015-02-06 18:12:48,867 DEBUG        5.0 kHz: SNR = 37.88 dB
+    2015-02-06 18:12:48,867 DEBUG        6.0 kHz: SNR = 38.58 dB
+    2015-02-06 18:12:48,867 DEBUG        7.0 kHz: SNR = 38.86 dB
+    2015-02-06 18:12:48,867 DEBUG        8.0 kHz: SNR = 38.63 dB
+    2015-02-06 18:12:48,867 DEBUG        9.0 kHz: SNR = 38.07 dB
+    2015-02-06 18:12:48,868 DEBUG       10.0 kHz: SNR = 37.22 dB
+    2015-02-06 18:12:48,869 INFO       Starting demodulation
+    2015-02-06 18:12:49,689 DEBUG      Got       6.000 kB, SNR: 41.19 dB, drift: -0.01 ppm
+    2015-02-06 18:12:50,659 DEBUG      Got      12.000 kB, SNR: 41.05 dB, drift: -0.00 ppm
+    2015-02-06 18:12:51,639 DEBUG      Got      18.000 kB, SNR: 40.96 dB, drift: -0.00 ppm
+    2015-02-06 18:12:52,610 DEBUG      Got      24.000 kB, SNR: 41.47 dB, drift: -0.01 ppm
+    2015-02-06 18:12:53,610 DEBUG      Got      30.000 kB, SNR: 41.06 dB, drift: -0.00 ppm
+    2015-02-06 18:12:54,589 DEBUG      Got      36.000 kB, SNR: 41.37 dB, drift: -0.00 ppm
+    2015-02-06 18:12:55,679 DEBUG      Got      42.000 kB, SNR: 41.13 dB, drift: -0.00 ppm
+    2015-02-06 18:12:56,650 DEBUG      Got      48.000 kB, SNR: 41.31 dB, drift: -0.00 ppm
+    2015-02-06 18:12:57,631 DEBUG      Got      54.000 kB, SNR: 41.23 dB, drift: +0.00 ppm
+    2015-02-06 18:12:58,605 DEBUG      Got      60.000 kB, SNR: 41.31 dB, drift: +0.00 ppm
+    2015-02-06 18:12:58,857 DEBUG      EOF frame detected
+    2015-02-06 18:12:58,857 DEBUG      Demodulated 61.205 kB @ 9.988 seconds (97.9% realtime)
+    2015-02-06 18:12:58,858 INFO       Received 60.000 kB @ 9.988 seconds = 6.007 kB/s
+    2015-02-06 18:12:58,876 DEBUG      Closing input and output
+    2015-02-06 18:12:58,951 DEBUG      AsyncReader thread stopped (read 896000 bytes)
+
+After the receiver has finished, verify the received file's hash::
+
+  ~/receiver $ sha256sum data.rx
+  008df57d4f3ed6e7a25d25afd57d04fc73140e8df604685bd34fcab58f5ddc01  data.rx
+
+You can see a screencast of the `data transfer process <https://asciinema.org/a/25066?autoplay=1>`_.
+
+I/O redirection
+---------------
+The audio can be written/read to an intermediate PCM file (instead of the speaker/microphone) using::
+
+    $ echo 123 | amodem send -o /tmp/file.pcm
+    Sending 0.800 seconds of training audio
+    Starting modulation
+    Sent 0.004 kB @ 0.113 seconds
+
+    $ amodem recv -i /tmp/file.pcm
+    Waiting for carrier tone: 2.0 kHz
+    Carrier detected at ~150.0 ms @ 2.0 kHz
+    Carrier coherence: 100.000%
+    Carrier symbols amplitude : 1.000
+    Frequency error: 0.000 ppm
+    Starting demodulation
+    123
+    Received 0.004 kB @ 0.011 seconds = 0.376 kB/s
+
+
+Visualization
+-------------
+Make sure that ``matplotlib`` package is installed, and run (at the receiver side)::
+
+    ~/receiver $ amodem recv --plot -o data.rx
+

amodem-cli

@@ -1,191 +0,0 @@
-#!/usr/bin/env python
-# PYTHON_ARGCOMPLETE_OK
-
-import os
-import sys
-import zlib
-import logging
-import argparse
-
-if sys.version_info.major == 2:
-    _stdin = sys.stdin
-    _stdout = sys.stdout
-else:
-    _stdin = sys.stdin.buffer
-    _stdout = sys.stdout.buffer
-
-try:
-    import argcomplete
-except ImportError:
-    argcomplete = None
-
-log = logging.getLogger('__name__')
-
-from amodem import recv, send, calib, audio
-from amodem.config import bitrates
-
-bitrate = os.environ.get('BITRATE', 1)
-config = bitrates.get(int(bitrate))
-
-
-class Compressor(object):
-    def __init__(self, stream):
-        self.obj = zlib.compressobj()
-        self.stream = stream
-
-    def read(self, size):
-        while True:
-            data = self.stream.read(size)
-            if data:
-                result = self.obj.compress(data)
-                if not result:  # compression is too good :)
-                    continue  # try again (since falsy data = EOF)
-            elif self.obj:
-                result = self.obj.flush()
-                self.obj = None
-            else:
-                result = ''  # EOF marker
-            return result
-
-
-class Decompressor(object):
-    def __init__(self, stream):
-        self.obj = zlib.decompressobj()
-        self.stream = stream
-
-    def write(self, data):
-        self.stream.write(self.obj.decompress(bytes(data)))
-
-    def flush(self):
-        self.stream.write(self.obj.flush())
-
-
-def FileType(mode, audio_interface=None):
-    def opener(fname):
-        assert 'r' in mode or 'w' in mode
-        if audio_interface is None and fname is None:
-            fname = '-'
-
-        if fname is None:
-            assert audio_interface is not None
-            if 'r' in mode:
-                return audio_interface.recorder()
-            if 'w' in mode:
-                return audio_interface.player()
-
-        if fname == '-':
-            if 'r' in mode:
-                return _stdin
-            if 'w' in mode:
-                return _stdout
-
-        return open(fname, mode)
-
-    return opener
-
-
-def main():
-    fmt = ('Audio OFDM MODEM: {0:.1f} kb/s ({1:d}-QAM x {2:d} carriers) '
-           'Fs={3:.1f} kHz')
-    description = fmt.format(config.modem_bps / 1e3, len(config.symbols),
-                             config.Nfreq, config.Fs / 1e3)
-    interface = audio.Interface('libportaudio.so', config=config)
-
-    p = argparse.ArgumentParser(description=description)
-    subparsers = p.add_subparsers()
-
-    def wrap(cls, stream, enable):
-        return cls(stream) if enable else stream
-
-    # Modulator
-    sender = subparsers.add_parser(
-        'send', help='modulate binary data into audio signal.')
-    sender.add_argument(
-        '-i', '--input', help='input file (use "-" for stdin).')
-    sender.add_argument(
-        '-o', '--output', help='output file (use "-" for stdout).'
-        ' if not specified, `aplay` tool will be used.')
-    sender.add_argument(
-        '-c', '--calibrate', default=False, action='store_true')
-
-    sender.set_defaults(
-        main=lambda config, args: send.main(
-            config, src=wrap(Compressor, args.src, args.zip), dst=args.dst
-        ),
-        calib=lambda config, args: calib.send(
-            config, dst=args.dst
-        ),
-        input_type=FileType('rb'),
-        output_type=FileType('wb', interface)
-    )
-
-    # Demodulator
-    receiver = subparsers.add_parser(
-        'recv', help='demodulate audio signal into binary data.')
-    receiver.add_argument(
-        '-i', '--input', help='input file (use "-" for stdin).'
-        ' if not specified, `arecord` tool will be used.')
-    receiver.add_argument(
-        '-o', '--output', help='output file (use "-" for stdout).')
-    receiver.add_argument(
-        '-c', '--calibrate', default=False, action='store_true')
-    receiver.add_argument(
-        '-d', '--dump', type=FileType('wb'),
-        help='Filename to save recorded audio')
-    receiver.add_argument(
-        '--plot', action='store_true', default=False,
-        help='plot results using pylab module')
-    receiver.set_defaults(
-        main=lambda config, args: recv.main(
-            config, src=args.src, dst=wrap(Decompressor, args.dst, args.zip),
-            pylab=args.pylab, dump_audio=args.dump
-        ),
-        calib=lambda config, args: calib.recv(
-            config, src=args.src, verbose=args.verbose
-        ),
-        input_type=FileType('rb', interface),
-        output_type=FileType('wb')
-    )
-
-    for sub in subparsers.choices.values():
-        sub.add_argument('-z', '--zip', default=False, action='store_true')
-        g = sub.add_mutually_exclusive_group()
-        g.add_argument('-v', '--verbose', default=0, action='count')
-        g.add_argument('-q', '--quiet', default=False, action='store_true')
-
-    if argcomplete:
-        argcomplete.autocomplete(p)
-
-    with interface:
-        args = p.parse_args()
-        if args.verbose == 0:
-            level, format = 'INFO', '%(message)s'
-        elif args.verbose == 1:
-            level, format = 'DEBUG', '%(message)s'
-        elif args.verbose >= 2:
-            level, format = ('DEBUG', '%(asctime)s %(levelname)-10s '
-                                      '%(message)-100s '
-                                      '%(filename)s:%(lineno)d')
-        if args.quiet:
-            level, format = 'WARNING', '%(message)s'
-        logging.basicConfig(level=level, format=format)
-
-        # Parsing and execution
-        log.debug(description)
-
-        args.pylab = None
-        if getattr(args, 'plot', False):
-            import pylab
-            args.pylab = pylab
-
-        args.src = args.input_type(args.input)
-        args.dst = args.output_type(args.output)
-        if args.calibrate:
-            args.calib(config=config, args=args)
-        else:
-            return args.main(config=config, args=args)
-
-
-if __name__ == '__main__':
-    success = main()
-    sys.exit(0 if success else 1)

amodem/__main__.py

@@ -0,0 +1,261 @@
+#!/usr/bin/env python
+# PYTHON_ARGCOMPLETE_OK
+import argparse
+import contextlib
+import logging
+import os
+import sys
+import zlib
+
+import pkg_resources
+
+from . import async_reader
+from . import audio
+from . import calib
+from . import main
+from .config import bitrates
+
+
+try:
+    import argcomplete
+except ImportError:
+    argcomplete = None
+
+log = logging.getLogger('__name__')
+
+bitrate = os.environ.get('BITRATE', 1)
+config = bitrates.get(int(bitrate))
+
+
+class Compressor:
+    def __init__(self, stream):
+        self.obj = zlib.compressobj()
+        log.info('Using zlib compressor')
+        self.stream = stream
+
+    def read(self, size):
+        while True:
+            data = self.stream.read(size)
+            if data:
+                result = self.obj.compress(data)
+                if not result:  # compression is too good :)
+                    continue  # try again (since falsy data = EOF)
+            elif self.obj:
+                result = self.obj.flush()
+                self.obj = None
+            else:
+                result = ''  # EOF marker
+            return result
+
+
+class Decompressor:
+    def __init__(self, stream):
+        self.obj = zlib.decompressobj()
+        log.info('Using zlib decompressor')
+        self.stream = stream
+
+    def write(self, data):
+        self.stream.write(self.obj.decompress(bytes(data)))
+
+    def flush(self):
+        self.stream.write(self.obj.flush())
+
+
+def FileType(mode, interface_factory=None):
+    def opener(fname):
+        audio_interface = interface_factory() if interface_factory else None
+
+        assert 'r' in mode or 'w' in mode
+        if audio_interface is None and fname is None:
+            fname = '-'
+
+        if fname is None:
+            assert audio_interface is not None
+            if 'r' in mode:
+                s = audio_interface.recorder()
+                return async_reader.AsyncReader(stream=s, bufsize=s.bufsize)
+            if 'w' in mode:
+                return audio_interface.player()
+
+        if fname == '-':
+            if 'r' in mode:
+                return sys.stdin.buffer
+            if 'w' in mode:
+                return sys.stdout.buffer
+
+        return open(fname, mode)  # pylint: disable=unspecified-encoding
+
+    return opener
+
+
+def get_volume_cmd(args):
+    volume_controllers = [{
+        'test': 'pactl --version',
+        'send': 'pactl set-sink-volume @DEFAULT_SINK@',
+        'recv': 'pactl set-source-volume @DEFAULT_SOURCE@'
+    }]
+    if args.calibrate == 'auto':
+        for c in volume_controllers:
+            if os.system(c['test']) == 0:
+                return c[args.command]
+    return None
+
+
+def wrap(cls, stream, enable):
+    return cls(stream) if enable else stream
+
+
+def create_parser(description, interface_factory):
+    p = argparse.ArgumentParser(description=description)
+    subparsers = p.add_subparsers(required=True)
+
+    # Modulator
+    sender = subparsers.add_parser(
+        'send', help='modulate binary data into audio signal.')
+    sender.add_argument(
+        '-i', '--input', help='input file (use "-" for stdin).')
+    sender.add_argument(
+        '-o', '--output', help='output file (use "-" for stdout).'
+        ' if not specified, `aplay` tool will be used.')
+    sender.add_argument(
+        '-g', '--gain', type=float, default=1.0,
+        help='Modulator gain (defaults to 1)')
+    sender.add_argument(
+        '--silence', type=float, default=0.0,
+        help='Extra silence before sending the data (in seconds)')
+    sender.set_defaults(
+        main=lambda config, args: main.send(
+            config, src=wrap(Compressor, args.src, args.zlib), dst=args.dst,
+            gain=args.gain, extra_silence=args.silence
+        ),
+        calib=lambda config, args: calib.send(
+            config=config, dst=args.dst,
+            volume_cmd=get_volume_cmd(args),
+            gain=args.gain,
+        ),
+        input_type=FileType('rb'),
+        output_type=FileType('wb', interface_factory),
+        command='send'
+    )
+
+    # Demodulator
+    receiver = subparsers.add_parser(
+        'recv', help='demodulate audio signal into binary data.')
+    receiver.add_argument(
+        '-i', '--input', help='input file (use "-" for stdin).')
+    receiver.add_argument(
+        '-o', '--output', help='output file (use "-" for stdout).')
+    receiver.add_argument(
+        '-d', '--dump', type=FileType('wb'),
+        help='Filename to save recorded audio')
+    receiver.add_argument(
+        '--plot', action='store_true', default=False,
+        help='plot results using pylab module')
+    receiver.set_defaults(
+        main=lambda config, args: main.recv(
+            config, src=args.src, dst=wrap(Decompressor, args.dst, args.zlib),
+            pylab=args.pylab, dump_audio=args.dump
+        ),
+        calib=lambda config, args: calib.recv(
+            config=config, src=args.src, verbose=args.verbose,
+            volume_cmd=get_volume_cmd(args)
+        ),
+        input_type=FileType('rb', interface_factory),
+        output_type=FileType('wb'),
+        command='recv'
+    )
+
+    calibration_help = ('Run calibration '
+                        '(specify "auto" for automatic gain control)')
+
+    for sub in subparsers.choices.values():
+        sub.add_argument('-c', '--calibrate', nargs='?', default=False,
+                         metavar='SYSTEM', help=calibration_help)
+        sub.add_argument('-l', '--audio-library', default='libportaudio.so',
+                         help='File name of PortAudio shared library.')
+        sub.add_argument('-z', '--zlib', default=False, action='store_true',
+                         help='Use zlib to compress/decompress data.')
+        g = sub.add_mutually_exclusive_group()
+        g.add_argument('-v', '--verbose', default=0, action='count')
+        g.add_argument('-q', '--quiet', default=False, action='store_true')
+
+    if argcomplete:
+        argcomplete.autocomplete(p)
+
+    return p
+
+
+def _version():
+    return pkg_resources.require('amodem')[0].version
+
+
+def _config_log(args):
+    level = fmt = None
+
+    if args.verbose == 0:
+        level, fmt = 'INFO', '%(message)s'
+    elif args.verbose == 1:
+        level, fmt = 'DEBUG', '%(message)s'
+    elif args.verbose >= 2:
+        level, fmt = ('DEBUG', '%(asctime)s %(levelname)-10s '
+                               '%(message)-100s '
+                               '%(filename)s:%(lineno)d')
+    if args.quiet:
+        level, fmt = 'WARNING', '%(message)s'
+    logging.basicConfig(level=level, format=fmt)
+
+
+def _main():
+    fmt = ('Audio OFDM MODEM v{0:s}: '
+           '{1:.1f} kb/s ({2:d}-QAM x {3:d} carriers) '
+           'Fs={4:.1f} kHz')
+    description = fmt.format(_version(),
+                             config.modem_bps / 1e3, len(config.symbols),
+                             config.Nfreq, config.Fs / 1e3)
+    interface = None
+
+    def interface_factory():
+        return interface
+
+    p = create_parser(description, interface_factory)
+
+    args = p.parse_args()
+    _config_log(args)
+
+    # Parsing and execution
+    log.info(description)
+
+    args.pylab = None
+    if getattr(args, 'plot', False):
+        import pylab  # pylint: disable=import-error,import-outside-toplevel
+        args.pylab = pylab
+
+    if args.audio_library == 'ALSA':
+        from . import alsa  # pylint: disable=import-outside-toplevel
+        interface = alsa.Interface(config)
+    elif args.audio_library == '-':
+        interface = contextlib.nullcontext()  # manually disable PortAudio
+    elif args.command == 'send' and args.output is not None:
+        interface = contextlib.nullcontext()  # redirected output
+    elif args.command == 'recv' and args.input is not None:
+        interface = contextlib.nullcontext()  # redirected input
+    else:
+        interface = audio.Interface(config)
+        interface.load(args.audio_library)
+
+    with interface:
+        args.src = args.input_type(args.input)
+        args.dst = args.output_type(args.output)
+        try:
+            if args.calibrate is False:
+                args.main(config=config, args=args)
+            else:
+                args.calib(config=config, args=args)
+        finally:
+            args.src.close()
+            args.dst.close()
+            log.debug('Finished I/O')
+
+
+if __name__ == '__main__':
+    _main()

amodem/alsa.py

@@ -0,0 +1,70 @@
+"""Code which adds Linux ALSA support for interfaces,
+recording and playing.
+
+"""
+
+import subprocess
+import logging
+
+log = logging.getLogger(__name__)
+
+
+class Interface:
+
+    RECORDER = 'arecord'
+    PLAYER = 'aplay'
+
+    def __init__(self, config):
+        self.config = config
+        rate = int(config.Fs)
+        bits_per_sample = config.bits_per_sample
+        assert bits_per_sample == 16
+
+        args = '-f S{0:d}_LE -c 1 -r {1:d} -T 100 -q -'
+        args = args.format(bits_per_sample, rate).split()
+
+        self.record_cmd = [self.RECORDER] + args
+        self.play_cmd = [self.PLAYER] + args
+        self.processes = []
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *args):
+        for p in self.processes:
+            try:
+                p.wait()
+            except OSError:
+                log.warning('%s failed', p)
+
+    def launch(self, **kwargs):
+        log.debug('Launching subprocess: %s', kwargs)
+        p = subprocess.Popen(**kwargs)
+        self.processes.append(p)
+        return p
+
+    def recorder(self):
+        return Recorder(self)
+
+    def player(self):
+        return Player(self)
+
+
+class Recorder:
+    def __init__(self, lib):
+        self.p = lib.launch(args=lib.record_cmd, stdout=subprocess.PIPE)
+        self.read = self.p.stdout.read
+        self.bufsize = 4096
+
+    def close(self):
+        self.p.kill()
+
+
+class Player:
+    def __init__(self, lib):
+        self.p = lib.launch(args=lib.play_cmd, stdin=subprocess.PIPE)
+        self.write = self.p.stdin.write
+
+    def close(self):
+        self.p.stdin.close()
+        self.p.wait()

amodem/async_reader.py

@@ -0,0 +1,52 @@
+"""Asynchronous Reading capabilities for amodem."""
+
+import logging
+import threading
+
+from queue import Queue
+
+log = logging.getLogger()
+
+
+class AsyncReader:
+    def __init__(self, stream, bufsize):
+        self.stream = stream
+        self.queue = Queue()
+        self.stop = threading.Event()
+        args = (stream, bufsize, self.queue, self.stop)
+        self.thread = threading.Thread(target=AsyncReader._thread,
+                                       args=args, name='AsyncReader')
+        self.thread.start()
+        self.buf = b''
+
+    @staticmethod
+    def _thread(src, bufsize, queue, stop):
+        total = 0
+        try:
+            log.debug('AsyncReader thread started')
+            while not stop.isSet():
+                buf = src.read(bufsize)
+                queue.put(buf)
+                total += len(buf)
+            log.debug('AsyncReader thread stopped (read %d bytes)', total)
+        except BaseException:  # pylint: disable=broad-except
+            log.exception('AsyncReader thread failed')
+            queue.put(None)
+
+    def read(self, size):
+        while len(self.buf) < size:
+            buf = self.queue.get()
+            if buf is None:
+                raise IOError('cannot read from stream')
+            self.buf += buf
+
+        result = self.buf[:size]
+        self.buf = self.buf[size:]
+        return result
+
+    def close(self):
+        if self.stream is not None:
+            self.stop.set()
+            self.thread.join()
+            self.stream.close()
+            self.stream = None

amodem/audio.py

@@ -1,22 +1,36 @@
+"""Audio capabilities for amodem."""
+
 import ctypes
 import logging
+import time
 
 log = logging.getLogger(__name__)
 
 
-class Interface(object):
-    def __init__(self, name, config, debug=False):
+class AudioError(Exception):
+    pass
+
+
+class Interface:
+    def __init__(self, config, debug=False):
         self.debug = bool(debug)
-        self.lib = ctypes.CDLL(name)
         self.config = config
         self.streams = []
-        assert self._error_string(0) == 'Success'
+        self.lib = None
+
+    def load(self, name):
+        self.lib = ctypes.CDLL(name)
+        assert self._error_string(0) == b'Success'
+        version = self.call('GetVersionText', restype=ctypes.c_char_p)
+        log.info('%s loaded', version)
+        return self
 
     def _error_string(self, code):
         return self.call('GetErrorText', code, restype=ctypes.c_char_p)
 
     def call(self, name, *args, **kwargs):
-        func_name = 'Pa_{0}'.format(name)
+        assert self.lib is not None
+        func_name = f'Pa_{name}'
         if self.debug:
             log.debug('API: %s%s', name, args)
         func = getattr(self.lib, func_name)
@@ -25,7 +39,7 @@ class Interface(object):
 
     def _error_check(self, res):
         if res != 0:
-            raise Exception(res, self._error_string(res))
+            raise AudioError(res, self._error_string(res))
 
     def __enter__(self):
         self.call('Initialize')
@@ -37,13 +51,15 @@ class Interface(object):
         self.call('Terminate')
 
     def recorder(self):
-        return Stream(lib=self, config=self.config, read=True)
+        return Stream(self, config=self.config, read=True)
 
     def player(self):
-        return Stream(lib=self, config=self.config, write=True)
+        return Stream(self, config=self.config, write=True)
 
 
-class Stream(object):
+class Stream:
+
+    timer = time.time
 
     class Parameters(ctypes.Structure):
         _fields_ = [
@@ -54,53 +70,63 @@ class Stream(object):
             ('hostApiSpecificStreamInfo', ctypes.POINTER(None))
         ]
 
-    def __init__(self, lib, config, read=False, write=False):
-        self.lib = lib
+    def __init__(self, interface, config, read=False, write=False):
+        self.interface = interface
         self.stream = ctypes.POINTER(ctypes.c_void_p)()
         self.user_data = ctypes.c_void_p(None)
         self.stream_callback = ctypes.c_void_p(None)
         self.bytes_per_sample = config.sample_size
+        self.latency = float(config.latency)  # in seconds
+        self.bufsize = int(self.latency * config.Fs * self.bytes_per_sample)
         assert config.bits_per_sample == 16  # just to make sure :)
 
         read = bool(read)
         write = bool(write)
-        assert read != write
+        assert read != write  # don't support full duplex
 
         direction = 'Input' if read else 'Output'
-        api_name = 'GetDefault{0}Device'.format(direction)
-        index = lib.call(api_name, restype=ctypes.c_int)
+        api_name = f'GetDefault{direction}Device'
+        index = interface.call(api_name, restype=ctypes.c_int)
         self.params = Stream.Parameters(
             device=index,               # choose default device
             channelCount=1,             # mono audio
             sampleFormat=0x00000008,    # 16-bit samples (paInt16)
-            suggestedLatency=0.1,       # 100ms should be good enough
+            suggestedLatency=self.latency,
             hostApiSpecificStreamInfo=None)
 
-        self.lib.call(
+        self.interface.call(
             'OpenStream',
             ctypes.byref(self.stream),
             ctypes.byref(self.params) if read else None,
             ctypes.byref(self.params) if write else None,
             ctypes.c_double(config.Fs),
-            ctypes.c_ulong(config.samples_per_buffer),
+            ctypes.c_ulong(0),  # (paFramesPerBufferUnspecified)
             ctypes.c_ulong(0),  # no flags (paNoFlag)
             self.stream_callback,
             self.user_data)
 
-        self.lib.streams.append(self)
-        self.lib.call('StartStream', self.stream)
+        self.interface.streams.append(self)
+        self.interface.call('StartStream', self.stream)
+        self.start_time = self.timer()
+        self.io_time = 0
 
     def close(self):
         if self.stream:
-            self.lib.call('StopStream', self.stream)
-            self.lib.call('CloseStream', self.stream)
+            self.interface.call('StopStream', self.stream)
+            self.interface.call('CloseStream', self.stream)
             self.stream = None
 
     def read(self, size):
         assert size % self.bytes_per_sample == 0
         buf = ctypes.create_string_buffer(size)
         frames = ctypes.c_ulong(size // self.bytes_per_sample)
-        self.lib.call('ReadStream', self.stream, buf, frames)
+        t0 = self.timer()
+        self.interface.call('ReadStream', self.stream, buf, frames)
+        t1 = self.timer()
+        self.io_time += (t1 - t0)
+        if self.interface.debug:
+            io_wait = self.io_time / (t1 - self.start_time)
+            log.debug('I/O wait: %.1f%%', io_wait * 100)
         return buf.raw
 
     def write(self, data):
@@ -108,4 +134,4 @@ class Stream(object):
         assert len(data) % self.bytes_per_sample == 0
         buf = ctypes.c_char_p(data)
         frames = ctypes.c_ulong(len(data) // self.bytes_per_sample)
-        self.lib.call('WriteStream', self.stream, buf, frames)
+        self.interface.call('WriteStream', self.stream, buf, frames)

amodem/calib.py

@@ -1,32 +1,45 @@
-import numpy as np
+"""Calibration capabilities for amodem."""
+
 import itertools
 import logging
+import subprocess
 
-log = logging.getLogger(__name__)
+import numpy as np
 
 from . import common
 from . import dsp
 from . import sampling
+from . import stream
 
-ALLOWED_EXCEPTIONS = (IOError, KeyboardInterrupt)
+log = logging.getLogger(__name__)
 
 
-def send(config, dst):
+def volume_controller(cmd):
+    def controller(level):
+        assert 0 < level <= 1
+        percent = 100 * level
+        args = f'{cmd} {percent:.0f}%'
+        log.debug('Setting volume to %7.3f%% -> "%s"', percent, args)
+        subprocess.check_call(args=args, shell=True)
+    return controller if cmd else (lambda level: None)
+
+
+def send(config, dst, volume_cmd=None, gain=1.0, limit=None):
+    volume_ctl = volume_controller(volume_cmd)
+    volume_ctl(1.0)  # full scale output volume
+
     calibration_symbols = int(1.0 * config.Fs)
     t = np.arange(0, calibration_symbols) * config.Ts
-    signals = [np.sin(2 * np.pi * f * t) for f in config.frequencies]
+    signals = [gain * np.sin(2 * np.pi * f * t) for f in config.frequencies]
     signals = [common.dumps(s) for s in signals]
 
-    try:
-        for signal in itertools.cycle(signals):
-            dst.write(signal)
-    except ALLOWED_EXCEPTIONS:
-        pass
+    for signal in itertools.islice(itertools.cycle(signals), limit):
+        dst.write(signal)
 
 
 def frame_iter(config, src, frame_length):
     frame_size = frame_length * config.Nsym * config.sample_size
-    omegas = 2 * np.pi * config.frequencies / config.Fs
+    omegas = 2 * np.pi * np.array(config.frequencies) / config.Fs
 
     while True:
         data = src.read(frame_size)
@@ -48,41 +61,81 @@ def frame_iter(config, src, frame_length):
 
 def detector(config, src, frame_length=200):
 
-    states = [True]
     errors = ['weak', 'strong', 'noisy']
-    try:
-        for coeffs, peak, total in frame_iter(config, src, frame_length):
-            max_index = np.argmax(coeffs)
-            freq = config.frequencies[max_index]
-            rms = abs(coeffs[max_index])
-            coherency = rms / total
-            flags = [rms > 0.1, peak < 1.0, coherency > 0.99]
+    for coeffs, peak, total in frame_iter(config, src, frame_length):
+        max_index = np.argmax(coeffs)
+        freq = config.frequencies[max_index]
+        rms = abs(coeffs[max_index])
+        coherency = rms / total if total > 0 else 0.0
+        flags = [total > 0.1, peak < 1.0, coherency > 0.99]
 
-            states.append(all(flags))
-            states = states[-2:]
-
-            message = 'good signal'
-            error = not any(states)
-            if error:
-                message = 'too {0} signal'.format(errors[flags.index(False)])
-
-            yield common.AttributeHolder(dict(
-                freq=freq, rms=rms, peak=peak, coherency=coherency,
-                total=total, error=error, message=message
-            ))
-    except ALLOWED_EXCEPTIONS:
-        pass
-
-
-def recv(config, src, verbose=False):
-    fmt = '{0.freq:6.0f} Hz: {0.message:s}'
-    if verbose:
-        fields = ['peak', 'total', 'rms', 'coherency']
-        fmt += ''.join(', {0}={{0.{0}:.4f}}'.format(f) for f in fields)
-
-    for result in detector(config=config, src=src):
-        msg = fmt.format(result)
-        if not result.error:
-            log.info(msg)
+        success = all(flags)
+        if success:
+            msg = 'good signal'
         else:
-            log.error(msg)
+            msg = f'too {errors[flags.index(False)]} signal'
+
+        yield {
+            'freq': freq, 'rms': rms, 'peak': peak, 'coherency': coherency,
+            'total': total, 'success': success, 'msg': msg
+        }
+
+
+def volume_calibration(result_iterator, volume_ctl):
+    min_level = 0.01
+    max_level = 1.0
+    level = 0.5
+    step = 0.25
+
+    target_level = 0.4  # not too strong, not too weak
+    iters_per_update = 10  # update every 2 seconds
+
+    for index, result in enumerate(itertools.chain([None], result_iterator)):
+        if index % iters_per_update == 0:
+            if index > 0:  # skip dummy (first result)
+                sign = 1 if (result['total'] < target_level) else -1
+                level = level + step * sign
+                level = min(max(level, min_level), max_level)
+                step = step * 0.5
+
+            volume_ctl(level)  # should run "before" first actual iteration
+
+        if index > 0:  # skip dummy (first result)
+            yield result
+
+
+def iter_window(iterable, size):
+    # pylint: disable=stop-iteration-return
+    block = []
+    for item in iterable:
+        block.append(item)
+        block = block[-size:]
+        if len(block) == size:
+            yield block
+
+
+def recv_iter(config, src, volume_cmd=None, dump_audio=None):
+    volume_ctl = volume_controller(volume_cmd)
+
+    if dump_audio:
+        src = stream.Dumper(src, dump_audio)
+    result_iterator = detector(config=config, src=src)
+    result_iterator = volume_calibration(result_iterator, volume_ctl)
+    for _prev, curr, _next in iter_window(result_iterator, size=3):
+        # don't log errors during frequency changes
+        if _prev['success'] and _next['success']:
+            if _prev['freq'] != _next['freq']:
+                if not curr['success']:
+                    curr['msg'] = 'frequency change'
+        yield curr
+
+
+def recv(config, src, verbose=False, volume_cmd=None, dump_audio=None):
+    fmt = '{freq:6.0f} Hz: {msg:20s}'
+    log.info('verbose: %s', verbose)
+    if verbose:
+        fields = ['total', 'rms', 'coherency', 'peak']
+        fmt += ', '.join(f'{f}={{{f}:.4f}}' for f in fields)
+
+    for state in recv_iter(config, src, volume_cmd, dump_audio):
+        log.info(fmt.format(**state))

amodem/common.py

@@ -1,28 +1,38 @@
+""" Common package functionality.
+Commom utilities and procedures for amodem.
+
+"""
+
 import itertools
+import logging
+
 import numpy as np
 
-import logging
 log = logging.getLogger(__name__)
 
 scaling = 32000.0  # out of 2**15
 
 
 def load(fileobj):
+    """ Load signal from file object. """
     return loads(fileobj.read())
 
 
 def loads(data):
+    """ Load signal from memory buffer. """
     x = np.frombuffer(data, dtype='int16')
     x = x / scaling
     return x
 
 
 def dumps(sym):
+    """ Dump signal to memory buffer. """
     sym = sym.real * scaling
     return sym.astype('int16').tostring()
 
 
 def iterate(data, size, func=None, truncate=True, index=False):
+    """ Iterate over a signal, taking each time *size* elements. """
     offset = 0
     data = iter(data)
 
@@ -40,6 +50,9 @@ def iterate(data, size, func=None, truncate=True, index=False):
 
 
 def split(iterable, n):
+    """ Split an iterable of n-tuples into n iterables of scalars.
+    The k-th iterable will be equivalent to (i[k] for i in iter).
+    """
     def _gen(it, index):
         for item in it:
             yield item[index]
@@ -49,37 +62,22 @@ def split(iterable, n):
 
 
 def icapture(iterable, result):
+    """ Appends each yielded item to result. """
     for i in iter(iterable):
         result.append(i)
         yield i
 
 
 def take(iterable, n):
+    """ Take n elements from iterable, and return them as a numpy array. """
     return np.array(list(itertools.islice(iterable, n)))
 
 
-# "Python 3" zip re-implementation for Python 2
-def izip(iterables):
-    iterables = [iter(iterable) for iterable in iterables]
-    while True:
-        yield tuple([next(iterable) for iterable in iterables])
-
-
-class Dummy(object):
+class Dummy:
+    """ Dummy placeholder object for testing and mocking. """
 
     def __getattr__(self, name):
         return self
 
     def __call__(self, *args, **kwargs):
         return self
-
-
-class AttributeHolder(object):
-
-    def __init__(self, d):
-        self.__dict__.update(d)
-
-    def __repr__(self):
-        items = sorted(self.__dict__.items())
-        args = ', '.join('{0}={1}'.format(k, v) for k, v in items)
-        return '{0}({1})'.format(self.__class__.__name__, args)

amodem/config.py

@@ -1,39 +1,48 @@
+"""Configuration class."""
+
 import numpy as np
 
 
-class Configuration(object):
+class Configuration:
     Fs = 32000.0  # sampling frequency [Hz]
     Tsym = 0.001  # symbol duration [seconds]
-    Nfreq = 8     # number of frequencies used
     Npoints = 64
-    F0 = 1e3
+    frequencies = [1e3, 8e3]  # use 1..8 kHz carriers
 
     # audio config
     bits_per_sample = 16
-    sample_size = bits_per_sample // 8
-    samples_per_buffer = 4096
+    latency = 0.1
 
     # sender config
-    silence_start = 1.0
-    silence_stop = 1.0
+    silence_start = 0.5
+    silence_stop = 0.5
 
     # receiver config
     skip_start = 0.1
+    timeout = 60.0
 
     def __init__(self, **kwargs):
         self.__dict__.update(**kwargs)
 
+        self.sample_size = self.bits_per_sample // 8
+        assert self.sample_size * 8 == self.bits_per_sample
+
         self.Ts = 1.0 / self.Fs
         self.Fsym = 1 / self.Tsym
-        self.frequencies = self.F0 + np.arange(self.Nfreq) * self.Fsym
+        self.Nsym = int(self.Tsym / self.Ts)
+        self.baud = int(1.0 / self.Tsym)
+        assert self.baud * self.Tsym == 1
+
+        if len(self.frequencies) != 1:
+            first, last = self.frequencies
+            self.frequencies = np.arange(first, last + self.baud, self.baud)
+
+        self.Nfreq = len(self.frequencies)
         self.carrier_index = 0
         self.Fc = self.frequencies[self.carrier_index]
 
-        self.Nsym = int(self.Tsym / self.Ts)
-        self.baud = int(1.0 / self.Tsym)
-
-        bits_per_symbol = np.log2(self.Npoints)
-        assert int(bits_per_symbol) == bits_per_symbol
+        bits_per_symbol = int(np.log2(self.Npoints))
+        assert 2 ** bits_per_symbol == self.Npoints
         self.bits_per_baud = bits_per_symbol * self.Nfreq
         self.modem_bps = self.baud * self.bits_per_baud
         self.carriers = np.array([
@@ -42,25 +51,40 @@ class Configuration(object):
         ])
 
         # QAM constellation
-        Nx = 2 ** int(np.ceil(bits_per_symbol / 2))
+        Nx = 2 ** int(np.ceil(bits_per_symbol // 2))
         Ny = self.Npoints // Nx
         symbols = [complex(x, y) for x in range(Nx) for y in range(Ny)]
         symbols = np.array(symbols)
         symbols = symbols - symbols[-1]/2
         self.symbols = symbols / np.max(np.abs(symbols))
 
+
 # MODEM configurations for various bitrates [kbps]
 bitrates = {
-    1: Configuration(F0=8e3, Npoints=2, Nfreq=1),
-    2: Configuration(F0=8e3, Npoints=4, Nfreq=1),
-    4: Configuration(F0=8e3, Npoints=16, Nfreq=1),
-    8: Configuration(F0=8e3, Npoints=16, Nfreq=2),
-    16: Configuration(F0=6e3, Npoints=16, Nfreq=4),
-    32: Configuration(F0=3e3, Npoints=16, Nfreq=8),
-    48: Configuration(F0=3e3, Npoints=64, Nfreq=8),
-    54: Configuration(F0=3e3, Npoints=64, Nfreq=9),
-    60: Configuration(F0=2e3, Npoints=64, Nfreq=10),
+    1: Configuration(Fs=8e3, Npoints=2, frequencies=[2e3]),
+    2: Configuration(Fs=8e3, Npoints=4, frequencies=[2e3]),
+    4: Configuration(Fs=8e3, Npoints=16, frequencies=[2e3]),
+    8: Configuration(Fs=8e3, Npoints=16, frequencies=[1e3, 2e3]),
+    12: Configuration(Fs=16e3, Npoints=16, frequencies=[3e3, 5e3]),
+    16: Configuration(Fs=16e3, Npoints=16, frequencies=[2e3, 5e3]),
+    20: Configuration(Fs=16e3, Npoints=16, frequencies=[2e3, 6e3]),
+    24: Configuration(Fs=16e3, Npoints=16, frequencies=[1e3, 6e3]),
+    28: Configuration(Fs=32e3, Npoints=16, frequencies=[3e3, 9e3]),
+    32: Configuration(Fs=32e3, Npoints=16, frequencies=[2e3, 9e3]),
+    36: Configuration(Fs=32e3, Npoints=64, frequencies=[4e3, 9e3]),
+    42: Configuration(Fs=32e3, Npoints=64, frequencies=[4e3, 10e3]),
+    48: Configuration(Fs=32e3, Npoints=64, frequencies=[3e3, 10e3]),
+    54: Configuration(Fs=32e3, Npoints=64, frequencies=[2e3, 10e3]),
+    60: Configuration(Fs=32e3, Npoints=64, frequencies=[2e3, 11e3]),
+    64: Configuration(Fs=32e3, Npoints=256, frequencies=[3e3, 10e3]),
+    72: Configuration(Fs=32e3, Npoints=256, frequencies=[2e3, 10e3]),
+    80: Configuration(Fs=32e3, Npoints=256, frequencies=[2e3, 11e3]),
 }
 
-fastest = lambda: bitrates[max(bitrates)]
-slowest = lambda: bitrates[min(bitrates)]
+
+def fastest():
+    return bitrates[max(bitrates)]
+
+
+def slowest():
+    return bitrates[min(bitrates)]

amodem/detect.py

@@ -1,24 +1,26 @@
-import numpy as np
-import logging
-import itertools
-import collections
+"""Signal detection capabilities for amodem."""
 
-log = logging.getLogger(__name__)
+import collections
+import itertools
+import logging
+
+import numpy as np
 
 from . import dsp
 from . import equalizer
 from . import common
 
+log = logging.getLogger(__name__)
 
-class Detector(object):
+
+class Detector:
 
     COHERENCE_THRESHOLD = 0.9
 
     CARRIER_DURATION = sum(equalizer.prefix)
     CARRIER_THRESHOLD = int(0.9 * CARRIER_DURATION)
     SEARCH_WINDOW = int(0.1 * CARRIER_DURATION)
-
-    TIMEOUT = 10.0  # [seconds]
+    START_PATTERN_LENGTH = SEARCH_WINDOW // 4
 
     def __init__(self, config, pylab):
         self.freq = config.Fc
@@ -26,7 +28,7 @@ class Detector(object):
         self.Nsym = config.Nsym
         self.Tsym = config.Tsym
         self.maxlen = config.baud  # 1 second of symbols
-        self.max_offset = self.TIMEOUT * config.Fs
+        self.max_offset = config.timeout * config.Fs
         self.plt = pylab
 
     def _wait(self, samples):
@@ -54,14 +56,9 @@ class Detector(object):
         length = (self.CARRIER_THRESHOLD - 1) * self.Nsym
         begin = offset - length
 
-        x = np.concatenate(tuple(bufs)[-self.CARRIER_THRESHOLD:-1])
-        Hc = dsp.exp_iwt(-self.omega, len(x))
-        amplitude = np.abs(np.dot(Hc, x) / (0.5 * len(x)))
         start_time = begin * self.Tsym / self.Nsym
-        log.info('Carrier detected at ~%.1f ms @ %.1f kHz:'
-                 ' coherence=%.3f%%, amplitude=%.3f',
-                 start_time * 1e3, self.freq / 1e3,
-                 np.abs(dsp.coherence(x, self.omega)) * 100, amplitude)
+        log.info('Carrier detected at ~%.1f ms @ %.1f kHz',
+                 start_time * 1e3, self.freq / 1e3)
 
         log.debug('Buffered %d ms of audio', len(bufs))
 
@@ -71,7 +68,7 @@ class Detector(object):
         bufs.append(np.array(trailing))
 
         buf = np.concatenate(bufs)
-        offset = self.find_start(buf, duration=self.CARRIER_DURATION)
+        offset = self.find_start(buf)
         start_time += (offset / self.Nsym - self.SEARCH_WINDOW) * self.Tsym
         log.debug('Carrier starts at %.3f ms', start_time * 1e3)
 
@@ -81,14 +78,21 @@ class Detector(object):
         amplitude, freq_err = self.estimate(buf[:prefix_length])
         return itertools.chain(buf, samples), amplitude, freq_err
 
-    def find_start(self, buf, duration):
-        filt = dsp.FIR(dsp.exp_iwt(self.omega, self.Nsym))
-        p = np.abs(list(filt(buf))) ** 2
-        p = np.cumsum(p)[self.Nsym-1:]
-        p = np.concatenate([[0], p])
-        length = (duration - 1) * self.Nsym
-        correlations = np.abs(p[length:] - p[:-length])
-        offset = np.argmax(correlations)
+    def find_start(self, buf):
+        carrier = dsp.exp_iwt(self.omega, self.Nsym)
+        carrier = np.tile(carrier, self.START_PATTERN_LENGTH)
+        zeroes = carrier * 0.0
+        signal = np.concatenate([zeroes, carrier])
+        signal = (2 ** 0.5) * signal / dsp.norm(signal)
+
+        corr = np.abs(np.correlate(buf, signal))
+        norm_b = np.sqrt(np.correlate(np.abs(buf)**2, np.ones(len(signal))))
+        coeffs = np.zeros_like(corr)
+        coeffs[norm_b > 0.0] = corr[norm_b > 0.0] / norm_b[norm_b > 0.0]
+
+        index = np.argmax(coeffs)
+        log.info('Carrier coherence: %.3f%%', coeffs[index] * 100)
+        offset = index + len(zeroes)
         return offset
 
     def estimate(self, buf, skip=5):
@@ -98,7 +102,7 @@ class Detector(object):
         symbols = np.array(symbols[skip:-skip])
 
         amplitude = np.mean(np.abs(symbols))
-        log.debug('Carrier symbols amplitude : %.3f', amplitude)
+        log.info('Carrier symbols amplitude : %.3f', amplitude)
 
         phase = np.unwrap(np.angle(symbols)) / (2 * np.pi)
         indices = np.arange(len(phase))
@@ -108,9 +112,6 @@ class Detector(object):
         self.plt.plot(indices, a * indices + b)
 
         freq_err = a / (self.Tsym * self.freq)
-        last_phase = a * indices[-1] + b
-        log.debug('Current phase on carrier: %.3f', last_phase)
-        log.debug('Frequency error: %.2f ppm', freq_err * 1e6)
-        self.plt.title('Frequency drift: {0:.3f} ppm'.format(freq_err * 1e6))
-
+        log.info('Frequency error: %.3f ppm', freq_err * 1e6)
+        self.plt.title(f'Frequency drift: {freq_err * 1e6:.3f} ppm')
         return amplitude, freq_err

amodem/dsp.py

@@ -1,10 +1,11 @@
+"""Digital Signal Processing capabilities for amodem."""
+
 import numpy as np
-from numpy import linalg
 
 from . import common
 
 
-class FIR(object):
+class FIR:
     def __init__(self, h):
         self.h = np.array(h)
         self.x_state = [0] * len(self.h)
@@ -18,33 +19,7 @@ class FIR(object):
         self.x_state = x_
 
 
-class IIR(object):
-    def __init__(self, b, a):
-        self.b = np.array(b) / a[0]
-        self.a = np.array(a[1:]) / a[0]
-        self.x_state = [0] * len(self.b)
-        self.y_state = [0] * (len(self.a) + 1)
-
-    def __call__(self, x):
-        x_, y_ = self.x_state, self.y_state
-        for v in x:
-            x_ = [v] + x_[:-1]
-            y_ = y_[:-1]
-            num = np.dot(x_, self.b)
-            den = np.dot(y_, self.a)
-            y = num - den
-            y_ = [y] + y_
-            yield y
-        self.x_state, self.y_state = x_, y_
-
-
-def lfilter(b, a, x):
-    f = IIR(b=b, a=a)
-    y = list(f(x))
-    return np.array(y)
-
-
-class Demux(object):
+class Demux:
     def __init__(self, sampler, omegas, Nsym):
         self.Nsym = Nsym
         self.filters = [exp_iwt(-w, Nsym) / (0.5*self.Nsym) for w in omegas]
@@ -58,8 +33,7 @@ class Demux(object):
         frame = self.sampler.take(size=self.Nsym)
         if len(frame) == self.Nsym:
             return np.dot(self.filters, frame)
-        else:
-            raise StopIteration
+        raise StopIteration
 
     __next__ = next
 
@@ -72,36 +46,40 @@ def norm(x):
     return np.sqrt(np.dot(x.conj(), x).real)
 
 
+def rms(x):
+    return np.mean(np.abs(x) ** 2, axis=0) ** 0.5
+
+
 def coherence(x, omega):
     n = len(x)
     Hc = exp_iwt(-omega, n) / np.sqrt(0.5*n)
     norm_x = norm(x)
-    if norm_x:
-        return np.dot(Hc, x) / norm_x
-    else:
+    if not norm_x:
         return 0.0
+    return np.dot(Hc, x) / norm_x
 
 
 def linear_regression(x, y):
-    ''' Find (a,b) such that y = a*x + b. '''
+    """ Find (a,b) such that y = a*x + b. """
     x = np.array(x)
     y = np.array(y)
-    ones = np.ones(len(x))
-    M = np.array([x, ones]).T
-    a, b = linalg.lstsq(M, y)[0]
+    mean_x = np.mean(x)
+    mean_y = np.mean(y)
+    x_ = x - mean_x
+    y_ = y - mean_y
+    a = np.dot(y_, x_) / np.dot(x_, x_)
+    b = mean_y - a * mean_x
     return a, b
 
 
-class MODEM(object):
-
-    buf_size = 16
+class MODEM:
 
     def __init__(self, symbols):
         self.encode_map = {}
         symbols = np.array(list(symbols))
         bits_per_symbol = np.log2(len(symbols))
         bits_per_symbol = np.round(bits_per_symbol)
-        N = (2 ** bits_per_symbol)
+        N = 2 ** bits_per_symbol
         assert N == len(symbols)
         bits_per_symbol = int(bits_per_symbol)
 
@@ -120,14 +98,28 @@ class MODEM(object):
             yield self.encode_map[bits_tuple]
 
     def decode(self, symbols, error_handler=None):
-        ''' Maximum-likelihood decoding, using naive nearest-neighbour. '''
+        """ Maximum-likelihood decoding, using naive nearest-neighbour. """
         symbols_vec = self.symbols
         _dec = self.decode_list
-        for syms in common.iterate(symbols, self.buf_size, truncate=False):
-            for received in syms:
-                error = np.abs(symbols_vec - received)
-                index = np.argmin(error)
-                decoded, bits = _dec[index]
-                if error_handler:
-                    error_handler(received=received, decoded=decoded)
-                yield bits
+        for received in symbols:
+            error = np.abs(symbols_vec - received)
+            index = np.argmin(error)
+            decoded, bits = _dec[index]
+            if error_handler:
+                error_handler(received=received, decoded=decoded)
+            yield bits
+
+
+def prbs(reg, poly, bits):
+    """ Simple pseudo-random number generator. """
+    mask = (1 << bits) - 1
+
+    size = 0  # effective register size (in bits)
+    while (poly >> size) > 1:
+        size += 1
+
+    while True:
+        yield reg & mask
+        reg = reg << 1
+        if reg >> size:
+            reg = reg ^ poly

amodem/equalizer.py

@@ -1,16 +1,15 @@
-import numpy as np
-from numpy.linalg import lstsq
-
-from amodem import dsp
-from amodem import sampling
+"""Audio equalizing capabilities for amodem."""
 
 import itertools
-import random
 
-_constellation = [1, 1j, -1, -1j]
+import numpy as np
+
+from . import dsp
+from . import sampling
+from . import levinson
 
 
-class Equalizer(object):
+class Equalizer:
 
     def __init__(self, config):
         self.carriers = config.carriers
@@ -18,10 +17,18 @@ class Equalizer(object):
         self.Nfreq = config.Nfreq
         self.Nsym = config.Nsym
 
-    def train_symbols(self, length, seed=0):
-        r = random.Random(seed)
-        choose = lambda: [r.choice(_constellation) for j in range(self.Nfreq)]
-        return np.array([choose() for _ in range(length)])
+    def train_symbols(self, length, constant_prefix=16):
+        r = dsp.prbs(reg=1, poly=0x1100b, bits=2)
+        constellation = [1, 1j, -1, -1j]
+
+        symbols = []
+        for _ in range(length):
+            symbols.append([constellation[next(r)] for _ in range(self.Nfreq)])
+
+        symbols = np.array(symbols)
+        # Constant symbols (for analog debugging)
+        symbols[:constant_prefix, :] = 1
+        return symbols
 
     def modulator(self, symbols):
         gain = 1.0 / len(self.carriers)
@@ -39,27 +46,21 @@ class Equalizer(object):
         return np.array(list(itertools.islice(symbols, size)))
 
 
+equalizer_length = 200
+silence_length = 50
+prefix = [1]*equalizer_length + [0]*silence_length
+
+
 def train(signal, expected, order, lookahead=0):
-    signal = [np.zeros(order-1), signal, np.zeros(lookahead)]
-    signal = np.concatenate(signal)
-    length = len(expected)
+    padding = np.zeros(lookahead)
+    assert len(signal) == len(expected)
+    x = np.concatenate([signal, padding])
+    y = np.concatenate([padding, expected])
 
-    A = []
-    b = []
-
-    for i in range(length - order):
-        offset = order + i
-        row = signal[offset-order:offset+lookahead]
-        A.append(np.array(row, ndmin=2))
-        b.append(expected[i])
-
-    A = np.concatenate(A, axis=0)
-    b = np.array(b)
-    h = lstsq(A, b)[0]
-    h = h[::-1].real
-    return h
-
-
-prefix = [1]*400 + [0]*50
-equalizer_length = 500
-silence_length = 100
+    N = order + lookahead  # filter length
+    Rxx = np.zeros(N)
+    Rxy = np.zeros(N)
+    for i in range(N):
+        Rxx[i] = np.dot(x[i:], x[:len(x)-i])
+        Rxy[i] = np.dot(y[i:], x[:len(x)-i])
+    return levinson.solver(t=Rxx, y=Rxy)

amodem/framing.py

@@ -1,17 +1,19 @@
-from . import common
-
+import binascii
 import functools
 import itertools
-import binascii
-import struct
 import logging
+import struct
+
+from . import common
+
 log = logging.getLogger(__name__)
 
-_checksum_func = lambda x: binascii.crc32(bytes(x)) & 0xFFFFFFFF
-# (so the result will be unsigned on Python 2/3)
+
+def _checksum_func(x):
+    return binascii.crc32(bytes(x))
 
 
-class Checksum(object):
+class Checksum:
     fmt = '>L'  # unsigned longs (32-bit)
     size = struct.calcsize(fmt)
 
@@ -24,12 +26,13 @@ class Checksum(object):
         payload = data[self.size:]
         expected = _checksum_func(payload)
         if received != expected:
-            log.warning('Invalid checksum: %04x != %04x', received, expected)
+            log.warning('Invalid checksum: %08x != %08x', received, expected)
             raise ValueError('Invalid checksum')
+        log.debug('Good checksum: %08x', received)
         return payload
 
 
-class Framer(object):
+class Framer:
     block_size = 250
     prefix_fmt = '>B'
     prefix_len = struct.calcsize(prefix_fmt)
@@ -83,7 +86,7 @@ def chain_wrapper(func):
     return wrapped
 
 
-class BitPacker(object):
+class BitPacker:
     byte_size = 8
 
     def __init__(self):
@@ -113,8 +116,7 @@ def _to_bytes(bits):
         yield [converter.to_byte[chunk]]
 
 
-@chain_wrapper
-def decode(bits, framer=None):
+def decode_frames(bits, framer=None):
     framer = framer or Framer()
     for frame in framer.decode(_to_bytes(bits)):
-        yield frame
+        yield bytes(frame)

amodem/levinson.py

@@ -0,0 +1,30 @@
+import numpy as np
+
+
+def solver(t, y):
+    """ Solve Mx = y for x, where M[i,j] = t[|i-j|], in O(N^2) steps.
+        See http://en.wikipedia.org/wiki/Levinson_recursion for details.
+    """
+    N = len(t)
+    assert len(y) == N
+
+    t0 = np.array([1.0 / t[0]])
+    f = [t0]  # forward vectors
+    b = [t0]  # backward vectors
+    for n in range(1, N):
+        prev_f = f[-1]
+        prev_b = b[-1]
+        ef = sum(t[n-i] * prev_f[i] for i in range(n))
+        eb = sum(t[i+1] * prev_b[i] for i in range(n))
+        f_ = np.concatenate([prev_f, [0]])
+        b_ = np.concatenate([[0], prev_b])
+        det = 1.0 - ef * eb
+        f.append((f_ - ef * b_) / det)
+        b.append((b_ - eb * f_) / det)
+
+    x = []
+    for n in range(N):
+        x = np.concatenate([x, [0]])
+        ef = sum(t[n-i] * x[i] for i in range(n))
+        x = x + (y[n] - ef) * b[n]
+    return x

amodem/main.py

@@ -0,0 +1,71 @@
+import itertools
+import logging
+
+import numpy as np
+
+from . import send as _send
+from . import recv as _recv
+from . import framing, common, stream, detect, sampling
+
+log = logging.getLogger(__name__)
+
+
+def send(config, src, dst, gain=1.0, extra_silence=0.0):
+    sender = _send.Sender(dst, config=config, gain=gain)
+    Fs = config.Fs
+
+    # pre-padding audio with silence (priming the audio sending queue)
+    sender.write(np.zeros(int(Fs * (config.silence_start + extra_silence))))
+
+    sender.start()
+
+    training_duration = sender.offset
+    log.info('Sending %.3f seconds of training audio', training_duration / Fs)
+
+    reader = stream.Reader(src, eof=True)
+    data = itertools.chain.from_iterable(reader)
+    bits = framing.encode(data)
+    log.info('Starting modulation')
+    sender.modulate(bits=bits)
+
+    data_duration = sender.offset - training_duration
+    log.info('Sent %.3f kB @ %.3f seconds',
+             reader.total / 1e3, data_duration / Fs)
+
+    # post-padding audio with silence
+    sender.write(np.zeros(int(Fs * config.silence_stop)))
+    return True
+
+
+def recv(config, src, dst, dump_audio=None, pylab=None):
+    if dump_audio:
+        src = stream.Dumper(src, dump_audio)
+    reader = stream.Reader(src, data_type=common.loads)
+    signal = itertools.chain.from_iterable(reader)
+
+    log.debug('Skipping %.3f seconds', config.skip_start)
+    common.take(signal, int(config.skip_start * config.Fs))
+
+    pylab = pylab or common.Dummy()
+    detector = detect.Detector(config=config, pylab=pylab)
+    receiver = _recv.Receiver(config=config, pylab=pylab)
+    try:
+        log.info('Waiting for carrier tone: %.1f kHz', config.Fc / 1e3)
+        signal, amplitude, freq_error = detector.run(signal)
+
+        freq = 1 / (1.0 + freq_error)  # receiver's compensated frequency
+        log.debug('Frequency correction: %.3f ppm', (freq - 1) * 1e6)
+
+        gain = 1.0 / amplitude
+        log.debug('Gain correction: %.3f', gain)
+
+        sampler = sampling.Sampler(signal, sampling.defaultInterpolator,
+                                   freq=freq)
+        receiver.run(sampler, gain=1.0/amplitude, output=dst)
+        return True
+    except BaseException:  # pylint: disable=broad-except
+        log.exception('Decoding failed')
+        return False
+    finally:
+        dst.flush()
+        receiver.report()

amodem/recv.py

@@ -1,21 +1,19 @@
-import numpy as np
-import logging
-import itertools
 import functools
+import itertools
+import logging
 import time
 
-log = logging.getLogger(__name__)
+import numpy as np
 
-from . import stream
 from . import dsp
-from . import sampling
 from . import common
 from . import framing
 from . import equalizer
-from . import detect
+
+log = logging.getLogger(__name__)
 
 
-class Receiver(object):
+class Receiver:
 
     def __init__(self, config, pylab=None):
         self.stats = {}
@@ -26,32 +24,36 @@ class Receiver(object):
         self.Nsym = config.Nsym
         self.Tsym = config.Tsym
         self.iters_per_update = 100  # [ms]
+        self.iters_per_report = 1000  # [ms]
         self.modem_bitrate = config.modem_bps
         self.equalizer = equalizer.Equalizer(config)
         self.carrier_index = config.carrier_index
         self.output_size = 0  # number of bytes written to output stream
+        self.freq_err_gain = 0.01 * self.Tsym  # integration feedback gain
 
     def _prefix(self, symbols, gain=1.0):
         S = common.take(symbols, len(equalizer.prefix))
         S = S[:, self.carrier_index] * gain
         sliced = np.round(np.abs(S))
         self.plt.figure()
-        self.plt.subplot(121)
+        self.plt.subplot(1, 2, 1)
         self._constellation(S, sliced, 'Prefix')
 
         bits = np.array(sliced, dtype=int)
-        self.plt.subplot(122)
+        self.plt.subplot(1, 2, 2)
         self.plt.plot(np.abs(S))
         self.plt.plot(equalizer.prefix)
-        if any(bits != equalizer.prefix):
-            raise ValueError('Incorrect prefix')
+        errors = bits != equalizer.prefix
+        if any(errors):
+            msg = f'Incorrect prefix: {sum(errors)} errors'
+            raise ValueError(msg)
         log.debug('Prefix OK')
 
     def _train(self, sampler, order, lookahead):
-        Nfreq = len(self.frequencies)
         equalizer_length = equalizer.equalizer_length
         train_symbols = self.equalizer.train_symbols(equalizer_length)
-        train_signal = self.equalizer.modulator(train_symbols) * Nfreq
+        train_signal = (self.equalizer.modulator(train_symbols) *
+                        len(self.frequencies))
 
         prefix = postfix = equalizer.silence_length * self.Nsym
         signal_length = equalizer_length * self.Nsym + prefix + postfix
@@ -60,7 +62,7 @@ class Receiver(object):
 
         coeffs = equalizer.train(
             signal=signal[prefix:-postfix],
-            expected=train_signal,
+            expected=np.concatenate([train_signal, np.zeros(lookahead)]),
             order=order, lookahead=lookahead
         )
 
@@ -68,6 +70,8 @@ class Receiver(object):
         self.plt.plot(np.arange(order+lookahead), coeffs)
 
         equalization_filter = dsp.FIR(h=coeffs)
+        log.debug('Training completed')
+        # Pre-load equalization filter with the signal (+lookahead)
         equalized = list(equalization_filter(signal))
         equalized = equalized[prefix+lookahead:-postfix+lookahead]
         self._verify_training(equalized, train_symbols)
@@ -77,31 +81,26 @@ class Receiver(object):
         equalizer_length = equalizer.equalizer_length
         symbols = self.equalizer.demodulator(equalized, equalizer_length)
         sliced = np.array(symbols).round()
-        errors = np.array(sliced - train_symbols, dtype=np.bool)
+        errors = np.array(sliced - train_symbols, dtype=bool)
         error_rate = errors.sum() / errors.size
 
         errors = np.array(symbols - train_symbols)
-        rms = lambda x: (np.mean(np.abs(x) ** 2, axis=0) ** 0.5)
 
-        noise_rms = rms(errors)
-        signal_rms = rms(train_symbols)
+        noise_rms = dsp.rms(errors)
+        signal_rms = dsp.rms(train_symbols)
         SNRs = 20.0 * np.log10(signal_rms / noise_rms)
 
         self.plt.figure()
         for (i, freq), snr in zip(enumerate(self.frequencies), SNRs):
             log.debug('%5.1f kHz: SNR = %5.2f dB', freq / 1e3, snr)
             self._constellation(symbols[:, i], train_symbols[:, i],
-                                '$F_c = {0} Hz$'.format(freq), index=i)
+                                f'$F_c = {freq} Hz$', index=i)
         assert error_rate == 0, error_rate
+        log.debug('Training verified')
 
-    def _demodulate(self, sampler, symbols):
+    def _bitstream(self, symbols, error_handler):
         streams = []
         symbol_list = []
-        errors = {}
-
-        def error_handler(received, decoded, freq):
-            errors.setdefault(freq, []).append(received / decoded)
-
         generators = common.split(symbols, n=len(self.omegas))
         for freq, S in zip(self.frequencies, generators):
             equalized = []
@@ -110,51 +109,68 @@ class Receiver(object):
 
             freq_handler = functools.partial(error_handler, freq=freq)
             bits = self.modem.decode(S, freq_handler)  # list of bit tuples
-            streams.append(bits)  # stream per frequency
+            streams.append(bits)  # bit stream per frequency
 
+        return zip(*streams), symbol_list
+
+    def _demodulate(self, sampler, symbols):
+        symbol_list = []
+        errors = {}
+        noise = {}
+
+        def _handler(received, decoded, freq):
+            errors.setdefault(freq, []).append(received / decoded)
+            noise.setdefault(freq, []).append(received - decoded)
+
+        stream, symbol_list = self._bitstream(symbols, _handler)
         self.stats['symbol_list'] = symbol_list
         self.stats['rx_bits'] = 0
         self.stats['rx_start'] = time.time()
 
         log.info('Starting demodulation')
-        for i, block in enumerate(common.izip(streams), 1):
-            for bits in block:
+        for i, block_of_bits in enumerate(stream, 1):
+            for bits in block_of_bits:
                 self.stats['rx_bits'] = self.stats['rx_bits'] + len(bits)
                 yield bits
 
             if i % self.iters_per_update == 0:
-                self._update_sampler(i, errors, sampler)
+                self._update_sampler(errors, sampler)
 
-    def _update_sampler(self, iter_index, errors, sampler):
+            if i % self.iters_per_report == 0:
+                self._report_progress(noise, sampler)
+
+    def _update_sampler(self, errors, sampler):
         err = np.array([e for v in errors.values() for e in v])
-        err = np.mean(np.angle(err))/(2*np.pi) if len(err) else 0
+        err = np.mean(np.angle(err))/(2*np.pi) if err.size else 0
         errors.clear()
 
-        duration = time.time() - self.stats['rx_start']
-        sampler.freq -= 0.01 * err * self.Tsym
+        sampler.freq -= self.freq_err_gain * err
         sampler.offset -= err
+
+    def _report_progress(self, noise, sampler):
+        e = np.array([e for v in noise.values() for e in v])
+        noise.clear()
         log.debug(
-            'Got  %10.3f kB, realtime: %6.2f%%, drift: %+5.2f ppm',
+            'Got  %10.3f kB, SNR: %5.2f dB, drift: %+5.2f ppm',
             self.stats['rx_bits'] / 8e3,
-            duration * 100.0 / (iter_index * self.Tsym),
+            -10 * np.log10(np.mean(np.abs(e) ** 2)),
             (1.0 - sampler.freq) * 1e6
         )
 
     def run(self, sampler, gain, output):
+        log.debug('Receiving')
         symbols = dsp.Demux(sampler, omegas=self.omegas, Nsym=self.Nsym)
         self._prefix(symbols, gain=gain)
 
-        filt = self._train(sampler, order=20, lookahead=20)
+        filt = self._train(sampler, order=10, lookahead=10)
         sampler.equalizer = lambda x: list(filt(x))
 
         bitstream = self._demodulate(sampler, symbols)
         bitstream = itertools.chain.from_iterable(bitstream)
 
-        data = framing.decode(bitstream)
-        for chunk in common.iterate(data=data, size=256,
-                                    truncate=False, func=bytearray):
-            output.write(chunk)
-            self.output_size += len(chunk)
+        for frame in framing.decode_frames(bitstream):
+            output.write(frame)
+            self.output_size += len(frame)
 
     def report(self):
         if self.stats:
@@ -172,7 +188,7 @@ class Receiver(object):
             symbol_list = np.array(self.stats['symbol_list'])
             for i, freq in enumerate(self.frequencies):
                 self._constellation(symbol_list[i], self.modem.symbols,
-                                    '$F_c = {0} Hz$'.format(freq), index=i)
+                                    f'$F_c = {freq} Hz$', index=i)
         self.plt.show()
 
     def _constellation(self, y, symbols, title, index=None):
@@ -192,47 +208,3 @@ class Receiver(object):
         self.plt.axis('equal')
         self.plt.axis(np.array([-1, 1, -1, 1])*1.1)
         self.plt.title(title)
-
-
-class Dumper(object):
-    def __init__(self, src, dst):
-        self.src = src
-        self.dst = dst
-
-    def read(self, size):
-        data = self.src.read(size)
-        self.dst.write(data)
-        return data
-
-
-def main(config, src, dst, dump_audio=None, pylab=None):
-    if dump_audio:
-        src = Dumper(src, dump_audio)
-    reader = stream.Reader(src, data_type=common.loads)
-    signal = itertools.chain.from_iterable(reader)
-
-    log.debug('Skipping %.3f seconds', config.skip_start)
-    common.take(signal, int(config.skip_start * config.Fs))
-
-    pylab = pylab or common.Dummy()
-    detector = detect.Detector(config=config, pylab=pylab)
-    receiver = Receiver(config=config, pylab=pylab)
-    try:
-        log.info('Waiting for carrier tone: %.1f kHz', config.Fc / 1e3)
-        signal, amplitude, freq_error = detector.run(signal)
-
-        freq = 1 / (1.0 + freq_error)  # receiver's compensated frequency
-        log.debug('Frequency correction: %.3f ppm', (freq - 1) * 1e6)
-
-        gain = 1.0 / amplitude
-        log.debug('Gain correction: %.3f', gain)
-
-        sampler = sampling.Sampler(signal, sampling.Interpolator(), freq=freq)
-        receiver.run(sampler, gain=1.0/amplitude, output=dst)
-        return True
-    except Exception:
-        log.exception('Decoding failed')
-        return False
-    finally:
-        dst.flush()
-        receiver.report()

amodem/sampling.py

@@ -1,11 +1,11 @@
-#!/usr/bin/env python
-import numpy as np
 import itertools
 
-from amodem import common
+import numpy as np
+
+from . import common
 
 
-class Interpolator(object):
+class Interpolator:
 
     def __init__(self, resolution=1024, width=128):
 
@@ -14,7 +14,7 @@ class Interpolator(object):
 
         N = resolution * width
         u = np.arange(-N, N, dtype=float)
-        window = (1 + np.cos(0.5 * np.pi * u / N)) / 2.0  # (Hann window)
+        window = np.cos(0.5 * np.pi * u / N) ** 2.0  # raised cosine
 
         h = np.sinc(u / resolution) * window
         self.filt = []
@@ -30,7 +30,10 @@ class Interpolator(object):
         assert len(self.filt) == resolution
 
 
-class Sampler(object):
+defaultInterpolator = Interpolator()
+
+
+class Sampler:
     def __init__(self, src, interp=None, freq=1.0):
         self.freq = freq
         self.equalizer = lambda x: x  # LTI equalization filter
@@ -57,26 +60,26 @@ class Sampler(object):
     def _take(self, size):
         frame = np.zeros(size)
         count = 0
-        try:
-            for frame_index in range(size):
-                offset = self.offset
-                # offset = k + (j / self.resolution)
-                k = int(offset)  # integer part
-                j = int((offset - k) * self.resolution)  # fractional part
-                coeffs = self.filt[j]  # choose correct filter phase
-                end = k + self.width
-                # process input until all buffer is full with samples
+        for frame_index in range(size):
+            offset = self.offset
+            # offset = k + (j / self.resolution)
+            k = int(offset)  # integer part
+            j = int((offset - k) * self.resolution)  # fractional part
+            coeffs = self.filt[j]  # choose correct filter phase
+            end = k + self.width
+            # process input until all buffer is full with samples
+            try:
                 while self.index < end:
                     self.buff[:-1] = self.buff[1:]
                     self.buff[-1] = next(self.src)  # throws StopIteration
                     self.index += 1
+            except StopIteration:
+                break
 
-                self.offset += self.freq
-                # apply interpolation filter
-                frame[frame_index] = np.dot(coeffs, self.buff)
-                count = frame_index + 1
-        except StopIteration:
-            pass
+            self.offset += self.freq
+            # apply interpolation filter
+            frame[frame_index] = np.dot(coeffs, self.buff)
+            count = frame_index + 1
 
         return self.equalizer(frame[:count])
 

amodem/send.py

@@ -1,18 +1,18 @@
-import numpy as np
-import logging
 import itertools
+import logging
 
-log = logging.getLogger(__name__)
+import numpy as np
 
 from . import common
-from . import stream
-from . import framing
 from . import equalizer
 from . import dsp
 
+log = logging.getLogger(__name__)
 
-class Sender(object):
-    def __init__(self, fd, config):
+
+class Sender:
+    def __init__(self, fd, config, gain=1.0):
+        self.gain = gain
         self.offset = 0
         self.fd = fd
         self.modem = dsp.MODEM(config.symbols)
@@ -24,7 +24,7 @@ class Sender(object):
         self.equalizer = equalizer.Equalizer(config)
 
     def write(self, sym):
-        sym = np.array(sym)
+        sym = np.array(sym) * self.gain
         data = common.dumps(sym)
         self.fd.write(data)
         self.offset += len(sym)
@@ -48,30 +48,3 @@ class Sender(object):
             if i % self.iters_per_report == 0:
                 total_bits = i * Nfreq * self.modem.bits_per_symbol
                 log.debug('Sent %10.3f kB', total_bits / 8e3)
-
-
-def main(config, src, dst):
-    sender = Sender(dst, config=config)
-    Fs = config.Fs
-
-    # pre-padding audio with silence
-    sender.write(np.zeros(int(Fs * config.silence_start)))
-
-    sender.start()
-
-    training_duration = sender.offset
-    log.info('Sending %.3f seconds of training audio', training_duration / Fs)
-
-    reader = stream.Reader(src, eof=True)
-    data = itertools.chain.from_iterable(reader)
-    bits = framing.encode(data)
-    log.info('Starting modulation')
-    sender.modulate(bits=bits)
-
-    data_duration = sender.offset - training_duration
-    log.info('Sent %.3f kB @ %.3f seconds',
-             reader.total / 1e3, data_duration / Fs)
-
-    # post-padding audio with silence
-    sender.write(np.zeros(int(Fs * config.silence_stop)))
-    return True

amodem/stream.py

@@ -1,11 +1,11 @@
 import time
 
 
-class Reader(object):
+class Reader:
 
     wait = 0.2
     timeout = 2.0
-    bufsize = 4096
+    bufsize = 8 << 10
 
     def __init__(self, fd, data_type=None, eof=False):
         self.fd = fd
@@ -24,8 +24,7 @@ class Reader(object):
                 self.total += len(data)
                 block.extend(data)
                 return block
-            else:
-                raise StopIteration()
+            raise StopIteration()
 
         finish_time = time.time() + self.timeout
         while time.time() <= finish_time:
@@ -43,3 +42,14 @@ class Reader(object):
         raise IOError('timeout')
 
     __next__ = next
+
+
+class Dumper:
+    def __init__(self, src, dst):
+        self.src = src
+        self.dst = dst
+
+    def read(self, size):
+        data = self.src.read(size)
+        self.dst.write(data)
+        return data

amodem/tests/test_alsa.py

@@ -0,0 +1,40 @@
+import mock
+
+from .. import alsa, config
+
+
+def test_alsa():
+    interface = alsa.Interface(config=config.fastest())
+    interface.launch = mock.Mock()
+    with interface:
+        r = interface.recorder()
+        r.read(2)
+        r.close()
+
+    p = mock.call(
+        args='arecord -f S16_LE -c 1 -r 32000 -T 100 -q -'.split(),
+        stdout=-1)
+    assert interface.launch.mock_calls == [p, p.stdout.read(2), p.kill()]
+
+    interface.launch = mock.Mock()
+    with interface:
+        p = interface.player()
+        p.write('\x00\x00')
+        p.close()
+
+    p = mock.call(
+        args='aplay -f S16_LE -c 1 -r 32000 -T 100 -q -'.split(),
+        stdin=-1)
+    assert interface.launch.mock_calls == [
+        p, p.stdin.write('\x00\x00'), p.stdin.close(), p.wait()
+    ]
+
+
+def test_alsa_subprocess():
+    interface = alsa.Interface(config=config.fastest())
+    with mock.patch('subprocess.Popen') as popen:
+        with interface:
+            p = interface.launch(args=['foobar'])
+            p.wait.side_effect = OSError('invalid command')
+            assert interface.processes == [p]
+            assert popen.mock_calls == [mock.call(args=['foobar'])]

amodem/tests/test_async_reader.py

@@ -0,0 +1,33 @@
+import logging
+import time
+
+import mock
+import pytest
+
+from .. import async_reader
+
+
+logging.basicConfig(format='%(message)s')
+
+
+def test_async_reader():
+    def _read(n):
+        time.sleep(n * 0.1)
+        return b'\x00' * n
+    s = mock.Mock()
+    s.read = _read
+    r = async_reader.AsyncReader(s, 1)
+
+    n = 5
+    assert r.read(n) == b'\x00' * n
+    r.close()
+    assert r.stream is None
+    r.close()
+
+
+def test_async_reader_error():
+    s = mock.Mock()
+    s.read.side_effect = IOError()
+    r = async_reader.AsyncReader(s, 1)
+    with pytest.raises(IOError):
+        r.read(3)

amodem/tests/test_audio.py

@@ -1,22 +1,21 @@
-from amodem import audio, config
-
 import mock
 import pytest
 
+from .. import audio, config
+
 
 def test():
     length = 1024
     data = b'\x12\x34' * length
     with mock.patch('ctypes.CDLL') as cdll:
         lib = mock.Mock()
-        lib.Pa_GetErrorText = lambda code: 'Error' if code else 'Success'
+        lib.Pa_GetErrorText = lambda code: b'Error' if code else b'Success'
         lib.Pa_GetDefaultOutputDevice.return_value = 1
         lib.Pa_GetDefaultInputDevice.return_value = 2
         lib.Pa_OpenStream.return_value = 0
         cdll.return_value = lib
-        interface = audio.Interface(
-            name='portaudio', config=config.fastest(), debug=True
-        )
+        interface = audio.Interface(config=config.fastest(), debug=True)
+        assert interface.load(name='portaudio') is interface
         with interface:
             s = interface.player()
             assert s.params.device == 1
@@ -32,4 +31,4 @@ def test():
             s.close()
 
         with pytest.raises(Exception):
-            interface._error_check(1)
+            interface._error_check(1)  # pylint: disable=protected-access

amodem/tests/test_calib.py

@@ -0,0 +1,159 @@
+from io import BytesIO
+import random
+
+import mock
+import numpy as np
+import pytest
+
+from .. import calib, common, config
+
+
+config = config.fastest()
+
+
+class ProcessMock:
+    def __init__(self):
+        self.buf = BytesIO()
+        self.stdin = self
+        self.stdout = self
+        self.bytes_per_sample = 2
+
+    def write(self, data):
+        assert self.buf.tell() < 10e6
+        self.buf.write(data)
+
+    def read(self, n):
+        return self.buf.read(n)
+
+
+def test_success():
+    p = ProcessMock()
+    calib.send(config, p, gain=0.5, limit=32)
+    p.buf.seek(0)
+    calib.recv(config, p)
+
+
+def test_too_strong():
+    p = ProcessMock()
+    calib.send(config, p, gain=1.001, limit=32)
+    p.buf.seek(0)
+    for r in calib.detector(config, src=p):
+        assert not r['success']
+        assert r['msg'] == 'too strong signal'
+
+
+def test_too_weak():
+    p = ProcessMock()
+    calib.send(config, p, gain=0.01, limit=32)
+    p.buf.seek(0)
+    for r in calib.detector(config, src=p):
+        assert not r['success']
+        assert r['msg'] == 'too weak signal'
+
+
+def test_too_noisy():
+    r = random.Random(0)  # generate random binary signal
+    signal = np.array([r.choice([-1, 1]) for i in range(int(config.Fs))])
+    src = BytesIO(common.dumps(signal * 0.5))
+    for r in calib.detector(config, src=src):
+        assert not r['success']
+        assert r['msg'] == 'too noisy signal'
+
+
+def test_errors():
+    class WriteError(ProcessMock):
+        def write(self, data):
+            raise KeyboardInterrupt()
+    p = WriteError()
+    with pytest.raises(KeyboardInterrupt):
+        calib.send(config, p, limit=32)
+    assert p.buf.tell() == 0
+
+    class ReadError(ProcessMock):
+        def read(self, n):
+            raise KeyboardInterrupt()
+    p = ReadError()
+    with pytest.raises(KeyboardInterrupt):
+        calib.recv(config, p, verbose=True)
+    assert p.buf.tell() == 0
+
+
+@pytest.fixture(params=[0] + [sign * mag for sign in (+1, -1)
+                              for mag in (0.1, 1, 10, 100, 1e3, 2e3)])
+def freq_err(request):
+    return request.param * 1e-6
+
+
+def test_drift(freq_err):
+    freq = config.Fc * (1 + freq_err / 1e6)
+    t = np.arange(int(1.0 * config.Fs)) * config.Ts
+    frame_length = 100
+    rms = 0.5
+    signal = rms * np.cos(2 * np.pi * freq * t)
+    src = BytesIO(common.dumps(signal))
+    iters = 0
+    for r in calib.detector(config, src, frame_length=frame_length):
+        assert r['success'] is True
+        assert abs(r['rms'] - rms) < 1e-3
+        assert abs(r['total'] - rms) < 1e-3
+        iters += 1
+
+    assert iters > 0
+    assert iters == config.baud / frame_length
+
+
+def test_volume():
+    with mock.patch('subprocess.check_call') as check_call:
+        ctl = calib.volume_controller('volume-control')
+        ctl(0.01)
+        ctl(0.421)
+        ctl(0.369)
+        ctl(1)
+        assert check_call.mock_calls == [
+            mock.call(shell=True, args='volume-control 1%'),
+            mock.call(shell=True, args='volume-control 42%'),
+            mock.call(shell=True, args='volume-control 37%'),
+            mock.call(shell=True, args='volume-control 100%')
+        ]
+        with pytest.raises(AssertionError):
+            ctl(0)
+        with pytest.raises(AssertionError):
+            ctl(-0.5)
+        with pytest.raises(AssertionError):
+            ctl(12.3)
+
+
+def test_send_max_volume():
+    with mock.patch('subprocess.check_call') as check_call:
+        calib.send(config, dst=BytesIO(), volume_cmd='ctl', limit=1)
+    assert check_call.mock_calls == [mock.call(shell=True, args='ctl 100%')]
+
+
+def test_recv_binary_search():
+    buf = BytesIO()
+    gains = [0.5, 0.25, 0.38, 0.44, 0.41, 0.39, 0.40, 0.40]
+    for gain in gains:
+        calib.send(config, buf, gain=gain, limit=2)
+    buf.seek(0)
+
+    dump = BytesIO()
+    with mock.patch('subprocess.check_call') as check_call:
+        calib.recv(config, src=buf, volume_cmd='ctl', dump_audio=dump)
+    assert dump.getvalue() == buf.getvalue()
+
+    gains.append(gains[-1])
+    fmt = 'ctl {0:.0f}%'
+    expected = [mock.call(shell=True, args=fmt.format(100 * g)) for g in gains]
+    assert check_call.mock_calls == expected
+
+
+def test_recv_freq_change():
+    p = ProcessMock()
+    calib.send(config, p, gain=0.5, limit=2)
+    offset = p.buf.tell() // 16
+    p.buf.seek(offset)
+    messages = [state['msg'] for state in calib.recv_iter(config, p)]
+    assert messages == [
+        'good signal', 'good signal', 'good signal',
+        'frequency change',
+        'good signal', 'good signal', 'good signal']

amodem/tests/test_common.py

@@ -1,6 +1,7 @@
-from amodem import common
 import numpy as np
 
+from .. import common, config
+
 
 def iterlist(x, *args, **kwargs):
     x = np.array(x)
@@ -47,15 +48,9 @@ def test_dumps_loads():
     assert all(x == y)
 
 
-def test_izip():
-    x = range(10)
-    y = range(-10, 0)
-    assert list(common.izip([x, y])) == list(zip(x, y))
-
-
-def test_holder():
-    d = {'x': 1, 'y': 2.3}
-    a = common.AttributeHolder(d)
-    assert a.x == d['x']
-    assert a.y == d['y']
-    assert repr(a) == 'AttributeHolder(x=1, y=2.3)'
+def test_configs():
+    default = config.Configuration()
+    fastest = config.fastest()
+    slowest = config.slowest()
+    assert slowest.modem_bps <= default.modem_bps
+    assert fastest.modem_bps >= default.modem_bps

amodem/tests/test_configs.py

@@ -0,0 +1,12 @@
+from .. import config
+
+
+def test_bitrates():
+    for rate, cfg in sorted(config.bitrates.items()):
+        assert rate * 1000 == cfg.modem_bps
+
+
+def test_slowest():
+    c = config.slowest()
+    assert c.Npoints == 2
+    assert list(c.symbols) == [-1j, 1j]

amodem/tests/test_detect.py

@@ -1,13 +1,8 @@
 import numpy as np
 import pytest
 
-from amodem import dsp
-from amodem import recv
-from amodem import detect
-from amodem import equalizer
-from amodem import sampling
-from amodem import config
-from amodem import common
+from .. import common, config, detect, dsp, equalizer, recv, sampling
+
 config = config.fastest()
 
 
@@ -17,9 +12,9 @@ def test_detect():
     x = np.cos(2 * np.pi * config.Fc * t)
 
     detector = detect.Detector(config, pylab=common.Dummy())
-    samples, amp, freq_err = detector.run(x)
+    _samples, amp, freq_err = detector.run(x)
     assert abs(1 - amp) < 1e-12
-    assert abs(freq_err) < 1e-16
+    assert abs(freq_err) < 1e-12
 
     x = np.cos(2 * np.pi * (2*config.Fc) * t)
     with pytest.raises(ValueError):
@@ -39,11 +34,11 @@ def test_prefix():
         sampler = sampling.Sampler(signal)
         return dsp.Demux(sampler=sampler, omegas=[omega], Nsym=config.Nsym)
     r = recv.Receiver(config, pylab=common.Dummy())
-    r._prefix(symbols_stream(signal))
+    r._prefix(symbols_stream(signal))  # pylint: disable=protected-access
 
     with pytest.raises(ValueError):
         silence = 0 * signal
-        r._prefix(symbols_stream(silence))
+        r._prefix(symbols_stream(silence))  # pylint: disable=protected-access
 
 
 def test_find_start():
@@ -56,6 +51,6 @@ def test_find_start():
     for offset in range(32):
         bufs = [prefix, [0] * offset, carrier, postfix]
         buf = np.concatenate(bufs)
-        start = detector.find_start(buf, length)
+        start = detector.find_start(buf)
         expected = offset + len(prefix)
         assert expected == start

amodem/tests/test_dsp.py

@@ -1,14 +1,13 @@
-import numpy as np
-from numpy.linalg import norm
-
-from amodem import dsp
-from amodem import sampling
-from amodem import config
-config = config.fastest()
-
 import random
 import itertools
 
+import numpy as np
+
+from .. import dsp, sampling, config
+from . import utils
+
+config = config.fastest()
+
 
 def test_linreg():
     x = np.array([1, 3, 2, 8, 4, 6, 9, 7, 0, 5])
@@ -21,11 +20,11 @@ def test_linreg():
 
 def test_filter():
     x = range(10)
-    y = dsp.lfilter(b=[1], a=[1], x=x)
+    y = utils.lfilter(b=[1], a=[1], x=x)
     assert (np.array(x) == y).all()
 
     x = [1] + [0] * 10
-    y = dsp.lfilter(b=[0.5], a=[1, -0.5], x=x)
+    y = utils.lfilter(b=[0.5], a=[1, -0.5], x=x)
     assert list(y) == [0.5 ** (i+1) for i in range(len(x))]
 
 
@@ -50,7 +49,9 @@ def test_qam():
     decoded = list(q.decode(S))
     assert decoded == bits
 
-    noise = lambda A: A*(r.uniform(-1, 1) + 1j*r.uniform(-1, 1))
+    def noise(A):
+        return A*(r.uniform(-1, 1) + 1j*r.uniform(-1, 1))
+
     noised_symbols = [(s + noise(1e-3)) for s in S]
     decoded = list(q.decode(noised_symbols))
     assert decoded == bits
@@ -67,6 +68,25 @@ def quantize(q, s):
 def test_overflow():
     q = dsp.MODEM(config.symbols)
     r = np.random.RandomState(seed=0)
-    for i in range(10000):
+    for _ in range(10000):
         s = 10*(r.normal() + 1j * r.normal())
         quantize(q, s)
+
+
+def test_prbs():
+    r = list(itertools.islice(dsp.prbs(reg=1, poly=0x7, bits=2), 4))
+    assert r == [1, 2, 3, 1]
+
+    r = list(itertools.islice(dsp.prbs(reg=1, poly=0x7, bits=1), 4))
+    assert r == [1, 0, 1, 1]
+
+    r = list(itertools.islice(dsp.prbs(reg=1, poly=0xd, bits=3), 8))
+    assert r == [1, 2, 4, 5, 7, 3, 6, 1]
+
+    r = list(itertools.islice(dsp.prbs(reg=1, poly=0xd, bits=2), 8))
+    assert r == [1, 2, 0, 1, 3, 3, 2, 1]
+
+    period = 2 ** 16 - 1
+    r = list(itertools.islice(dsp.prbs(reg=1, poly=0x1100b, bits=16), period))
+    r.sort()
+    assert r == list(range(1, 2 ** 16))

amodem/tests/test_equalizer.py

@@ -1,15 +1,16 @@
-from numpy.linalg import norm
 from numpy.random import RandomState
 import numpy as np
 
-from amodem import dsp
-from amodem import equalizer
-from amodem import config
+from . import utils
+from .. import config, dsp, equalizer
+
 config = config.fastest()
 
 
 def assert_approx(x, y, e=1e-12):
-    assert norm(x - y) < e * norm(x)
+    x = x.flatten()
+    y = y.flatten()
+    assert dsp.norm(x - y) < e * dsp.norm(x)
 
 
 def test_training():
@@ -24,14 +25,14 @@ def test_commutation():
     x = np.random.RandomState(seed=0).normal(size=1000)
     b = [1, 1j, -1, -1j]
     a = [1, 0.1]
-    y = dsp.lfilter(x=x, b=b, a=a)
-    y1 = dsp.lfilter(x=dsp.lfilter(x=x, b=b, a=[1]), b=[1], a=a)
-    y2 = dsp.lfilter(x=dsp.lfilter(x=x, b=[1], a=a), b=b, a=[1])
+    y = utils.lfilter(x=x, b=b, a=a)
+    y1 = utils.lfilter(x=utils.lfilter(x=x, b=b, a=[1]), b=[1], a=a)
+    y2 = utils.lfilter(x=utils.lfilter(x=x, b=[1], a=a), b=b, a=[1])
     assert_approx(y, y1)
     assert_approx(y, y2)
 
-    z = dsp.lfilter(x=y, b=a, a=[1])
-    z_ = dsp.lfilter(x=x, b=b, a=[1])
+    z = utils.lfilter(x=y, b=a, a=[1])
+    z_ = utils.lfilter(x=x, b=b, a=[1])
     assert_approx(z, z_)
 
 
@@ -46,19 +47,20 @@ def test_modem():
 
 
 def test_signal():
-    length = 100
+    length = 120
     x = np.sign(RandomState(0).normal(size=length))
+    x[-20:] = 0  # make sure the signal has bounded support
     den = np.array([1, -0.6, 0.1])
     num = np.array([0.5])
-    y = dsp.lfilter(x=x, b=num, a=den)
+    y = utils.lfilter(x=x, b=num, a=den)
 
     lookahead = 2
     h = equalizer.train(
         signal=y, expected=x, order=len(den), lookahead=lookahead)
-    assert norm(h[:lookahead]) < 1e-12
+    assert dsp.norm(h[:lookahead]) < 1e-12
 
     h = h[lookahead:]
     assert_approx(h, den / num)
 
-    x_ = dsp.lfilter(x=y, b=h, a=[1])
+    x_ = utils.lfilter(x=y, b=h, a=[1])
     assert_approx(x_, x)

amodem/tests/test_framing.py

@@ -1,13 +1,15 @@
-from amodem import framing
-import random
 import itertools
+import random
 
 import pytest
 
+from .. import framing
+
 
 def concat(iterable):
     return bytearray(itertools.chain.from_iterable(iterable))
 
+
 r = random.Random(0)
 blob = bytearray(r.randrange(0, 256) for i in range(64 * 1024))
 
@@ -31,22 +33,22 @@ def test_framer(data):
 
 def test_main(data):
     encoded = framing.encode(data)
-    decoded = framing.decode(encoded)
-    assert bytearray(decoded) == data
+    decoded = framing.decode_frames(encoded)
+    assert concat(decoded) == data
 
 
 def test_fail():
     encoded = list(framing.encode(''))
     encoded[-1] = not encoded[-1]
     with pytest.raises(ValueError):
-        list(framing.decode(encoded))
+        concat(framing.decode_frames(encoded))
 
 
 def test_missing():
     f = framing.Framer()
     with pytest.raises(ValueError):
-        list(f.decode(b''))
+        concat(f.decode(b''))
     with pytest.raises(ValueError):
-        list(f.decode(b'\x01'))
+        concat(f.decode(b'\x01'))
     with pytest.raises(ValueError):
-        list(f.decode(b'\xff'))
+        concat(f.decode(b'\xff'))

amodem/tests/test_sampling.py

@@ -1,8 +1,8 @@
-from amodem import sampling
-from amodem import common
+from io import BytesIO
 
 import numpy as np
-from io import BytesIO
+
+from .. import common, sampling
 
 
 def test_resample():
@@ -20,6 +20,6 @@ def test_resample():
 
 
 def test_coeffs():
-    I = sampling.Interpolator(width=4, resolution=16)
-    err = I.filt[0] - [0, 0, 0, 1, 0, 0, 0, 0]
+    interp = sampling.Interpolator(width=4, resolution=16)
+    err = interp.filt[0] - [0, 0, 0, 1, 0, 0, 0, 0]
     assert np.max(np.abs(err)) < 1e-10

amodem/tests/test_stream.py

@@ -1,5 +1,7 @@
-from amodem import stream
 import subprocess as sp
+import sys
+
+from .. import stream
 
 script = br"""
 import sys
@@ -14,7 +16,7 @@ while True:
 
 
 def test_read():
-    p = sp.Popen(args=['python', '-'], stdin=sp.PIPE, stdout=sp.PIPE)
+    p = sp.Popen(args=[sys.executable, '-'], stdin=sp.PIPE, stdout=sp.PIPE)
     p.stdin.write(script)
     p.stdin.close()
     f = stream.Reader(p.stdout)
@@ -29,7 +31,6 @@ def test_read():
         j += 1
 
     try:
-        for buf in f:
-            pass
+        next(f)
     except IOError as e:
         assert e.args == ('timeout',)

amodem/tests/test_transfer.py

@@ -1,35 +1,23 @@
-import os
 from io import BytesIO
+import logging
+import os
 
 import numpy as np
-
-from amodem import send
-from amodem import recv
-from amodem import common
-from amodem import dsp
-from amodem import sampling
-from amodem import config
-config = config.fastest()
-
-import logging
-logging.basicConfig(level=logging.DEBUG,
-                    format='%(asctime)s %(levelname)-12s %(message)s')
-
 import pytest
 
+from .. import common, config, main, sampling
+from . import utils
 
-class Args(object):
-    def __init__(self, **kwargs):
-        self.__dict__.update(kwargs)
-
-    def __getattr__(self, name):
-        return None
+logging.basicConfig(level=logging.DEBUG,  # useful for debugging
+                    format='%(asctime)s %(levelname)-12s %(message)s')
 
 
-def run(size, chan=None, df=0, success=True):
+def run(size, chan=None, df=0, success=True, cfg=None):
+    if cfg is None:
+        cfg = config.fastest()
     tx_data = os.urandom(size)
     tx_audio = BytesIO()
-    send.main(config=config, src=BytesIO(tx_data), dst=tx_audio)
+    main.send(config=cfg, src=BytesIO(tx_data), dst=tx_audio, gain=0.5)
 
     data = tx_audio.getvalue()
     data = common.loads(data)
@@ -42,26 +30,44 @@ def run(size, chan=None, df=0, success=True):
 
     data = common.dumps(data)
     rx_audio = BytesIO(data)
-
     rx_data = BytesIO()
-    d = BytesIO()
-    result = recv.main(config=config, src=rx_audio, dst=rx_data,
-                       dump_audio=d)
+    dump = BytesIO()
+
+    try:
+        result = main.recv(config=cfg, src=rx_audio, dst=rx_data,
+                           dump_audio=dump, pylab=None)
+    finally:
+        rx_audio.close()
+
     rx_data = rx_data.getvalue()
-    assert data.startswith(d.getvalue())
+    assert data.startswith(dump.getvalue())
 
     assert result == success
     if success:
         assert rx_data == tx_data
 
 
-@pytest.fixture(params=[0, 1, 3, 10, 42, 123])
+@pytest.fixture(params=[0, 1, 3, 10, 16, 17, 42, 123])
 def small_size(request):
     return request.param
 
 
-def test_small(small_size):
-    run(small_size, chan=lambda x: x)
+@pytest.fixture(params=list(config.bitrates.values()))
+def all_configs(request):
+    return request.param
+
+
+def test_small(small_size, all_configs):
+    run(small_size, chan=lambda x: x, cfg=all_configs)
+
+
+def test_flip():
+    run(16, chan=lambda x: -x)
+
+
+def test_large_drift():
+    run(1, df=+0.01)
+    run(1, df=-0.01)
 
 
 def test_error():
@@ -70,7 +76,7 @@ def test_error():
 
 
 @pytest.fixture(params=[sign * mag for sign in (+1, -1)
-                        for mag in (0.1, 1, 10, 100, 1e3, 2e3)])
+                        for mag in (0.1, 1, 10, 100, 1e3, 10e3)])
 def freq_err(request):
     return request.param * 1e-6
 
@@ -80,11 +86,11 @@ def test_timing(freq_err):
 
 
 def test_lowpass():
-    run(1024, chan=lambda x: dsp.lfilter(b=[0.9], a=[1.0, -0.1], x=x))
+    run(1024, chan=lambda x: utils.lfilter(b=[0.9], a=[1.0, -0.1], x=x))
 
 
 def test_highpass():
-    run(1024, chan=lambda x: dsp.lfilter(b=[0.9], a=[1.0, 0.1], x=x))
+    run(1024, chan=lambda x: utils.lfilter(b=[0.9], a=[1.0, 0.1], x=x))
 
 
 def test_attenuation():
@@ -103,3 +109,12 @@ def test_medium_noise():
 
 def test_large():
     run(54321, chan=lambda x: x)
+
+
+@pytest.fixture(params=sorted(config.bitrates.keys()))
+def rate(request):
+    return request.param
+
+
+def test_rate(rate):
+    run(1, cfg=config.bitrates[rate])

amodem/tests/utils.py

@@ -0,0 +1,27 @@
+import numpy as np
+
+
+class IIR:
+    def __init__(self, b, a):
+        self.b = np.array(b) / a[0]
+        self.a = np.array(a[1:]) / a[0]
+        self.x_state = [0] * len(self.b)
+        self.y_state = [0] * (len(self.a) + 1)
+
+    def __call__(self, x):
+        x_, y_ = self.x_state, self.y_state
+        for v in x:
+            x_ = [v] + x_[:-1]
+            y_ = y_[:-1]
+            num = np.dot(x_, self.b)
+            den = np.dot(y_, self.a)
+            y = num - den
+            y_ = [y] + y_
+            yield y
+        self.x_state, self.y_state = x_, y_
+
+
+def lfilter(b, a, x):
+    f = IIR(b=b, a=a)
+    y = list(f(x))
+    return np.array(y)

pyproject.toml

@@ -0,0 +1,37 @@
+[project]
+name = "amodem"
+version = "1.16.0"
+authors = [
+  { name="Roman Zeyde", email="dev@romanzey.de" },
+]
+description = "Audio Modem Communication Library"
+readme = "README.md"
+license = {text = "MIT"}
+requires-python = ">=3.7"
+dependencies = [
+  "numpy",
+]
+classifiers = [
+    "Development Status :: 5 - Production/Stable",
+    "Intended Audience :: Developers",
+    "Intended Audience :: Information Technology",
+    "License :: OSI Approved :: MIT License",
+    "Operating System :: POSIX",
+    "Programming Language :: Python :: 3.7",
+    "Programming Language :: Python :: 3.8",
+    "Programming Language :: Python :: 3.9",
+    "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3.11",
+    "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: 3.13",
+    "Topic :: Software Development :: Libraries :: Python Modules",
+    "Topic :: System :: Networking",
+    "Topic :: Communications",
+]
+
+[project.scripts]
+amodem = "amodem.__main__:_main"
+
+[project.urls]
+Homepage = "https://github.com/romanz/amodem"
+Issues = "https://github.com/romanz/amodem/issues"

requirements.txt

@@ -1,2 +0,0 @@
-numpy
-argcomplete

scripts/autocalib.sh

@@ -0,0 +1,2 @@
+#!/bin/bash
+amodem-cli send -vv -c auto | amodem-cli recv -vv -c auto

scripts/play.sh

@@ -0,0 +1,2 @@
+#!/bin/bash
+aplay -f S16_LE -c 1 -r 32000 $*

scripts/plot.py

@@ -1,6 +1,16 @@
 #!/usr/bin/env python
+
+"""Script that exposes pylab's spectogram plotting
+capabilities to the command line. It implements this
+for amodem.config Configurations.
+
+"""
+
 import pylab
 import numpy as np
+from amodem import common
+from amodem.config import Configuration
+import sys
 
 
 def spectrogram(t, x, Fs, NFFT=256):
@@ -11,10 +21,8 @@ def spectrogram(t, x, Fs, NFFT=256):
     pylab.specgram(x, NFFT=NFFT, Fs=Fs, noverlap=NFFT/2,
                    cmap=pylab.cm.gist_heat)
 
-if __name__ == '__main__':
-    import sys
-    from amodem import common
-    from amodem.config import Configuration
+
+def main():
     config = Configuration()
 
     for fname in sys.argv[1:]:
@@ -25,3 +33,7 @@ if __name__ == '__main__':
         spectrogram(t, x, config.Fs)
 
     pylab.show()
+
+
+if __name__ == '__main__':
+    main()

scripts/profile.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+set -x -u
+SRC=`tempfile`
+DST=`tempfile`
+AUDIO=`tempfile`
+dd if=/dev/urandom of=$SRC bs=1kB count=1000
+export BITRATE=80
+time python -m cProfile -o send.prof amodem-cli send -l- -vv -i $SRC -o $AUDIO 2> send.log
+echo -e "sort cumtime\nstats" | python -m pstats send.prof > send.prof.txt
+
+time python -m cProfile -o recv.prof amodem-cli recv -l- -vv -i $AUDIO -o $DST 2> recv.log
+echo -e "sort cumtime\nstats" | python -m pstats recv.prof > recv.prof.txt
+
+diff $SRC $DST || echo "ERROR!"
+rm $SRC $DST $AUDIO

scripts/record.py

@@ -0,0 +1,35 @@
+#!/usr/bin/env python
+
+"""Script that records audio through an interface
+and stores it into an amodem.config Configuration.
+
+"""
+import argparse
+from amodem import audio
+from amodem.config import Configuration
+
+
+def run(args):
+    config = Configuration()
+    with open(args.filename, 'wb') as dst:
+        interface = audio.Interface(config=config)
+        with interface.load(args.audio_library):
+            src = interface.recorder()
+            size = int(config.sample_size * config.Fs)  # one second of audio
+            while True:
+                dst.write(src.read(size))
+
+
+def main():
+    p = argparse.ArgumentParser()
+    p.add_argument('-l', '--audio-library', default='libportaudio.so')
+    p.add_argument('filename')
+
+    try:
+        run(args=p.parse_args())
+    except KeyboardInterrupt:
+        return
+
+
+if __name__ == '__main__':
+    main()

scripts/record.sh

@@ -0,0 +1,2 @@
+#!/bin/bash
+arecord -f S16_LE -c 1 -r 32000 $*

scripts/resample

@@ -1,5 +0,0 @@
-#!/usr/bin/env python
-from amodem.sampling import resample
-import sys
-
-resample(src=sys.stdin, dst=sys.stdout, df=float(sys.argv[1]))

scripts/resample.py

@@ -0,0 +1,22 @@
+#!/usr/bin/env python
+
+"""Script that exposes the amodem.resample() function
+to the command line, taking parameters via standard
+inputs and returning results via standard outputs.
+"""
+
+from amodem.sampling import resample
+import argparse
+import sys
+
+
+def main():
+    p = argparse.ArgumentParser()
+    p.add_argument('df', type=float)
+    args = p.parse_args()
+
+    resample(src=sys.stdin, dst=sys.stdout, df=args.df)
+
+
+if __name__ == '__main__':
+    main()

setup.py

@@ -1,46 +0,0 @@
-#!/usr/bin/env python
-from setuptools import setup
-from setuptools.command.test import test as TestCommand
-
-
-class PyTest(TestCommand):
-
-    def finalize_options(self):
-        self.test_args = []
-        self.test_suite = True
-
-    def run_tests(self):
-        import sys
-        import pytest
-        sys.exit(pytest.main(['tests']))
-
-setup(
-    name="amodem",
-    version="1.6",
-    description="Audio Modem Communication Library",
-    author="Roman Zeyde",
-    author_email="roman.zeyde@gmail.com",
-    license="MIT",
-    url="http://github.com/romanz/amodem",
-    packages=['amodem'],
-    tests_require=['pytest'],
-    cmdclass={'test': PyTest},
-    install_requires=['numpy'],
-    platforms=['POSIX'],
-    classifiers=[
-        "Development Status :: 4 - Beta",
-        "Intended Audience :: Developers",
-        "Intended Audience :: Information Technology",
-        "License :: OSI Approved :: MIT License",
-        "Operating System :: POSIX",
-        "Programming Language :: Python :: 2.6",
-        "Programming Language :: Python :: 2.7",
-        "Programming Language :: Python :: 3.2",
-        "Programming Language :: Python :: 3.3",
-        "Programming Language :: Python :: 3.4",
-        "Topic :: Software Development :: Libraries :: Python Modules",
-        "Topic :: System :: Networking",
-        "Topic :: Communications",
-    ],
-    scripts=['amodem-cli'],
-)

tests/test_calib.py

@@ -1,80 +0,0 @@
-from amodem import calib
-from amodem import common
-from amodem import config
-config = config.fastest()
-
-from io import BytesIO
-
-import numpy as np
-import pytest
-
-
-class ProcessMock(object):
-    def __init__(self):
-        self.buf = BytesIO()
-        self.stdin = self
-        self.stdout = self
-        self.bytes_per_sample = 2
-
-    def launch(self, *args, **kwargs):
-        return self
-
-    __call__ = launch
-
-    def kill(self):
-        pass
-
-    def write(self, data):
-        self.buf.write(data)
-        if self.buf.tell() > 1e6:
-            raise KeyboardInterrupt
-
-    def read(self, n):
-        return self.buf.read(n)
-
-
-def test_success():
-    p = ProcessMock()
-    calib.send(config, p)
-    p.buf.seek(0)
-    calib.recv(config, p)
-
-
-def test_errors():
-    class WriteError(ProcessMock):
-        def write(self, data):
-            raise IOError()
-    p = WriteError()
-    calib.send(config, p)
-    assert p.buf.tell() == 0
-
-    class ReadError(ProcessMock):
-        def read(self, n):
-            raise KeyboardInterrupt()
-    p = ReadError()
-    calib.recv(config, p, verbose=True)
-    assert p.buf.tell() == 0
-
-
-@pytest.fixture(params=[0] + [sign * mag for sign in (+1, -1)
-                              for mag in (0.1, 1, 10, 100, 1e3, 2e3)])
-def freq_err(request):
-    return request.param * 1e-6
-
-
-def test_drift(freq_err):
-    freq = config.Fc * (1 + freq_err / 1e6)
-    t = np.arange(int(1.0 * config.Fs)) * config.Ts
-    frame_length = 100
-    rms = 0.5
-    signal = rms * np.cos(2 * np.pi * freq * t)
-    src = BytesIO(common.dumps(signal))
-    iters = 0
-    for r in calib.detector(config, src, frame_length=frame_length):
-        assert not r.error
-        assert abs(r.rms - rms) < 1e-3
-        assert abs(r.total - rms) < 1e-3
-        iters += 1
-
-    assert iters > 0
-    assert iters == config.baud / frame_length

tox.ini

@@ -1,14 +1,14 @@
 [tox]
-envlist = py27,py34
+envlist = py3
 [testenv]
 deps=
 	pytest
 	mock
-	pep8
+	pycodestyle
 	coverage
 	pylint
 commands=
-	pep8 amodem/ scripts/ tests/ amodem-cli
-	pylint --disable no-member --report=no amodem
-	coverage run --source amodem/ -m py.test tests/
+	pycodestyle amodem/ scripts/
+	pylint --extension-pkg-whitelist=numpy --reports=no amodem --rcfile .pylintrc
+	coverage run --source amodem/ --omit="*/__main__.py" -m pytest -v
 	coverage report