Fix division by 0 during calibration

Fix pytest usage

.bumpversion.cfg

@@ -1,7 +1,6 @@
 [bumpversion]
 commit = True
 tag = True
-current_version = 1.13.1
+current_version = 1.15.4
 
 [bumpversion:file:setup.py]
-

.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"]
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install
+      run: |
+        python -m pip install --upgrade pip
+        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

@@ -24,4 +24,6 @@ htmlcov
 *_ext.so
 /.tox
 /dist
+/deb_dist
 *.html
+.pytest_cache/

.pylintrc

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

.travis.yml

@@ -1,22 +0,0 @@
-sudo: false
-language: python
-python:
-  - "2.7"
-  - "3.3"
-  - "3.4"
-  - "3.5"
-  - "3.6"
-
-install:
-  - pip install .
-  - pip install pytest>=2.7.3 --upgrade
-  - pip install coveralls pycodestyle mock
-
-script:
-  - pycodestyle amodem/ scripts/
-  - echo "Hello World!" | amodem send -vv -l- -o- | amodem recv -vv -l- -i-
-  - coverage run --source=amodem --omit="*/__main__.py" -m py.test -vvs
-
-after_success:
-  - coverage report
-  - coveralls

README.rst

@@ -1,16 +1,6 @@
 Audio Modem Communication Library
 =================================
 
-.. image:: https://travis-ci.org/romanz/amodem.svg?branch=master
-    :target: https://travis-ci.org/romanz/amodem
-    :alt: Build Status
-.. image:: https://coveralls.io/repos/romanz/amodem/badge.svg?branch=master
-    :target: https://coveralls.io/r/romanz/amodem?branch=master
-    :alt: Code Coverage
-.. image:: https://landscape.io/github/romanz/amodem/master/landscape.svg?style=flat
-    :target: https://landscape.io/github/romanz/amodem/master
-    :alt: Code Health
-
 .. image:: https://img.shields.io/pypi/pyversions/amodem.svg
     :target: https://pypi.python.org/pypi/amodem/
     :alt: Python Versions
@@ -24,9 +14,6 @@ Audio Modem Communication Library
     :target: https://pypi.python.org/pypi/amodem/
     :alt: Development Status
 
-.. image:: https://badge.waffle.io/romanz/amodem.svg?label=ready&title=ready
-    :target: https://waffle.io/romanz/amodem
-    :alt: 'Ready'
 
 Description
 -----------
@@ -45,6 +32,8 @@ 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
 -----------------
 
@@ -64,9 +53,9 @@ on each 250 byte data frame.
 Installation
 ------------
 
-Make sure that ``numpy`` and ``PortAudio v19`` packages are installed (on Debian)::
+Make sure that all the required packages are installed (on Debian)::
 
-    $ sudo apt-get install python-numpy portaudio19-dev
+    $ sudo apt-get install python-numpy python-pip portaudio19-dev git
 
 Get the latest released version from PyPI::
 
@@ -96,6 +85,12 @@ For validation, run::
     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
 -----------
@@ -225,6 +220,26 @@ After the receiver has finished, verify the received file's hash::
 
 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)::

amodem/__main__.py

@@ -8,18 +8,13 @@ import zlib
 
 import pkg_resources
 
-from . import async
+from . import async_reader
 from . import audio
 from . import calib
 from . import main
 from .config import bitrates
 
 
-# Python 3 has `buffer` attribute for byte-based I/O
-_stdin = getattr(sys.stdin, 'buffer', sys.stdin)
-_stdout = getattr(sys.stdout, 'buffer', sys.stdout)
-
-
 try:
     import argcomplete
 except ImportError:
@@ -31,7 +26,7 @@ bitrate = os.environ.get('BITRATE', 1)
 config = bitrates.get(int(bitrate))
 
 
-class Compressor(object):
+class Compressor:
     def __init__(self, stream):
         self.obj = zlib.compressobj()
         log.info('Using zlib compressor')
@@ -52,7 +47,7 @@ class Compressor(object):
             return result
 
 
-class Decompressor(object):
+class Decompressor:
     def __init__(self, stream):
         self.obj = zlib.decompressobj()
         log.info('Using zlib decompressor')
@@ -77,27 +72,27 @@ def FileType(mode, interface_factory=None):
             assert audio_interface is not None
             if 'r' in mode:
                 s = audio_interface.recorder()
-                return async.AsyncReader(stream=s, bufsize=s.bufsize)
+                return async_reader.AsyncReader(stream=s, bufsize=s.bufsize)
             if 'w' in mode:
                 return audio_interface.player()
 
         if fname == '-':
             if 'r' in mode:
-                return _stdin
+                return sys.stdin.buffer
             if 'w' in mode:
-                return _stdout
+                return sys.stdout.buffer
 
-        return open(fname, mode)
+        return open(fname, mode)  # pylint: disable=unspecified-encoding
 
     return opener
 
 
 def get_volume_cmd(args):
-    volume_controllers = [
-        dict(test='pactl --version',
-             send='pactl set-sink-volume @DEFAULT_SINK@',
-             recv='pactl set-source-volume @DEFAULT_SOURCE@')
-    ]
+    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:
@@ -111,7 +106,7 @@ def wrap(cls, stream, enable):
 
 def create_parser(description, interface_factory):
     p = argparse.ArgumentParser(description=description)
-    subparsers = p.add_subparsers()
+    subparsers = p.add_subparsers(required=True)
 
     # Modulator
     sender = subparsers.add_parser(
@@ -124,10 +119,13 @@ def create_parser(description, interface_factory):
     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
+            gain=args.gain, extra_silence=args.silence
         ),
         calib=lambda config, args: calib.send(
             config=config, dst=args.dst,
@@ -142,8 +140,7 @@ def create_parser(description, interface_factory):
     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.')
+        '-i', '--input', help='input file (use "-" for stdin).')
     receiver.add_argument(
         '-o', '--output', help='output file (use "-" for stdout).')
     receiver.add_argument(
@@ -186,7 +183,7 @@ def create_parser(description, interface_factory):
     return p
 
 
-class _Dummy(object):
+class _Dummy:
     def __enter__(self):
         return self
 
@@ -198,6 +195,20 @@ def _version():
     return pkg_resources.require('amodem')[0].version
 
 
+def _config_log(args):
+    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) '
@@ -213,31 +224,25 @@ def _main():
     p = create_parser(description, interface_factory)
 
     args = p.parse_args()
-    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)
+    _config_log(args)
 
     # Parsing and execution
-    log.debug(description)
+    log.info(description)
 
     args.pylab = None
     if getattr(args, 'plot', False):
-        import pylab  # pylint: disable=import-error
+        import pylab  # pylint: disable=import-error,import-outside-toplevel
         args.pylab = pylab
 
     if args.audio_library == 'ALSA':
-        from . import alsa
+        from . import alsa  # pylint: disable=import-outside-toplevel
         interface = alsa.Interface(config)
     elif args.audio_library == '-':
-        interface = _Dummy()
+        interface = _Dummy()  # manually disable PortAudio
+    elif args.command == 'send' and args.output is not None:
+        interface = _Dummy()  # redirected output
+    elif args.command == 'recv' and args.input is not None:
+        interface = _Dummy()  # redirected input
     else:
         interface = audio.Interface(config)
         interface.load(args.audio_library)

amodem/alsa.py

@@ -9,7 +9,7 @@ import logging
 log = logging.getLogger(__name__)
 
 
-class Interface(object):
+class Interface:
 
     RECORDER = 'arecord'
     PLAYER = 'aplay'
@@ -50,7 +50,7 @@ class Interface(object):
         return Player(self)
 
 
-class Recorder(object):
+class Recorder:
     def __init__(self, lib):
         self.p = lib.launch(args=lib.record_cmd, stdout=subprocess.PIPE)
         self.read = self.p.stdout.read
@@ -60,7 +60,7 @@ class Recorder(object):
         self.p.kill()
 
 
-class Player(object):
+class Player:
     def __init__(self, lib):
         self.p = lib.launch(args=lib.play_cmd, stdin=subprocess.PIPE)
         self.write = self.p.stdin.write

amodem/async_reader.py

@@ -3,15 +3,15 @@
 import logging
 import threading
 
-import six  # since `Queue` module was renamed to `queue` (in Python 3)
+from queue import Queue
 
 log = logging.getLogger()
 
 
-class AsyncReader(object):
+class AsyncReader:
     def __init__(self, stream, bufsize):
         self.stream = stream
-        self.queue = six.moves.queue.Queue()
+        self.queue = Queue()
         self.stop = threading.Event()
         args = (stream, bufsize, self.queue, self.stop)
         self.thread = threading.Thread(target=AsyncReader._thread,
@@ -29,7 +29,7 @@ class AsyncReader(object):
                 queue.put(buf)
                 total += len(buf)
             log.debug('AsyncReader thread stopped (read %d bytes)', total)
-        except BaseException:
+        except BaseException:  # pylint: disable=broad-except
             log.exception('AsyncReader thread failed')
             queue.put(None)
 

amodem/audio.py

@@ -7,7 +7,11 @@ import time
 log = logging.getLogger(__name__)
 
 
-class Interface(object):
+class AudioError(Exception):
+    pass
+
+
+class Interface:
     def __init__(self, config, debug=False):
         self.debug = bool(debug)
         self.config = config
@@ -26,7 +30,7 @@ class Interface(object):
 
     def call(self, name, *args, **kwargs):
         assert self.lib is not None
-        func_name = 'Pa_{0}'.format(name)
+        func_name = f'Pa_{name}'
         if self.debug:
             log.debug('API: %s%s', name, args)
         func = getattr(self.lib, func_name)
@@ -35,7 +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')
@@ -53,7 +57,7 @@ class Interface(object):
         return Stream(self, config=self.config, write=True)
 
 
-class Stream(object):
+class Stream:
 
     timer = time.time
 
@@ -81,7 +85,7 @@ class Stream(object):
         assert read != write  # don't support full duplex
 
         direction = 'Input' if read else 'Output'
-        api_name = 'GetDefault{0}Device'.format(direction)
+        api_name = f'GetDefault{direction}Device'
         index = interface.call(api_name, restype=ctypes.c_int)
         self.params = Stream.Parameters(
             device=index,               # choose default device

amodem/calib.py

@@ -18,7 +18,7 @@ def volume_controller(cmd):
     def controller(level):
         assert 0 < level <= 1
         percent = 100 * level
-        args = '{0} {1:.0f}%'.format(cmd, percent)
+        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)
@@ -66,19 +66,19 @@ def detector(config, src, frame_length=200):
         max_index = np.argmax(coeffs)
         freq = config.frequencies[max_index]
         rms = abs(coeffs[max_index])
-        coherency = rms / total
+        coherency = rms / total if total > 0 else 0.0
         flags = [total > 0.1, peak < 1.0, coherency > 0.99]
 
         success = all(flags)
         if success:
             msg = 'good signal'
         else:
-            msg = 'too {0} signal'.format(errors[flags.index(False)])
+            msg = f'too {errors[flags.index(False)]} signal'
 
-        yield dict(
-            freq=freq, rms=rms, peak=peak, coherency=coherency,
-            total=total, success=success, msg=msg
-        )
+        yield {
+            'freq': freq, 'rms': rms, 'peak': peak, 'coherency': coherency,
+            'total': total, 'success': success, 'msg': msg
+        }
 
 
 def volume_calibration(result_iterator, volume_ctl):
@@ -107,8 +107,7 @@ def volume_calibration(result_iterator, volume_ctl):
 def iter_window(iterable, size):
     # pylint: disable=stop-iteration-return
     block = []
-    while True:
-        item = next(iterable)
+    for item in iterable:
         block.append(item)
         block = block[-size:]
         if len(block) == size:
@@ -136,7 +135,7 @@ def recv(config, src, verbose=False, volume_cmd=None, dump_audio=None):
     log.info('verbose: %s', verbose)
     if verbose:
         fields = ['total', 'rms', 'coherency', 'peak']
-        fmt += ', '.join('{0}={{{0}:.4f}}'.format(f) for f in fields)
+        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

@@ -73,15 +73,7 @@ def take(iterable, n):
     return np.array(list(itertools.islice(iterable, n)))
 
 
-def izip(iterables):
-    """ "Python 3" zip re-implementation for Python 2. """
-    # pylint: disable=stop-iteration-return
-    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):

amodem/config.py

@@ -3,7 +3,7 @@
 import numpy as np
 
 
-class Configuration(object):
+class Configuration:
     Fs = 32000.0  # sampling frequency [Hz]
     Tsym = 0.001  # symbol duration [seconds]
     Npoints = 64
@@ -14,8 +14,8 @@ class Configuration(object):
     latency = 0.1
 
     # sender config
-    silence_start = 0.25
-    silence_stop = 0.25
+    silence_start = 0.5
+    silence_stop = 0.5
 
     # receiver config
     skip_start = 0.1

amodem/detect.py

@@ -13,7 +13,7 @@ from . import common
 log = logging.getLogger(__name__)
 
 
-class Detector(object):
+class Detector:
 
     COHERENCE_THRESHOLD = 0.9
 
@@ -85,12 +85,10 @@ class Detector(object):
         signal = np.concatenate([zeroes, carrier])
         signal = (2 ** 0.5) * signal / dsp.norm(signal)
 
-        coeffs = []
-        for i in range(len(buf) - len(signal)):
-            b = buf[i:i+len(signal)]
-            norm_b = dsp.norm(b)
-            c = (np.abs(np.dot(b, signal)) / norm_b) if norm_b else 0.0
-            coeffs.append(c)
+        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)
@@ -115,5 +113,5 @@ class Detector(object):
 
         freq_err = a / (self.Tsym * self.freq)
         log.info('Frequency error: %.3f ppm', freq_err * 1e6)
-        self.plt.title('Frequency drift: {0:.3f} ppm'.format(freq_err * 1e6))
+        self.plt.title(f'Frequency drift: {freq_err * 1e6:.3f} ppm')
         return amplitude, freq_err

amodem/dsp.py

@@ -5,7 +5,7 @@ import numpy as np
 from . import common
 
 
-class FIR(object):
+class FIR:
     def __init__(self, h):
         self.h = np.array(h)
         self.x_state = [0] * len(self.h)
@@ -19,7 +19,7 @@ class FIR(object):
         self.x_state = x_
 
 
-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]
@@ -33,8 +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
 
@@ -73,14 +72,14 @@ def linear_regression(x, y):
     return a, b
 
 
-class MODEM(object):
+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)
 

amodem/equalizer.py

@@ -9,7 +9,7 @@ from . import sampling
 from . import levinson
 
 
-class Equalizer(object):
+class Equalizer:
 
     def __init__(self, config):
         self.carriers = config.carriers
@@ -46,9 +46,9 @@ class Equalizer(object):
         return np.array(list(itertools.islice(symbols, size)))
 
 
-prefix = [1]*200 + [0]*50
 equalizer_length = 200
 silence_length = 50
+prefix = [1]*equalizer_length + [0]*silence_length
 
 
 def train(signal, expected, order, lookahead=0):

amodem/framing.py

@@ -10,11 +10,10 @@ log = logging.getLogger(__name__)
 
 
 def _checksum_func(x):
-    ''' The result will be unsigned on Python 2/3. '''
-    return binascii.crc32(bytes(x)) & 0xFFFFFFFF
+    return binascii.crc32(bytes(x))
 
 
-class Checksum(object):
+class Checksum:
     fmt = '>L'  # unsigned longs (32-bit)
     size = struct.calcsize(fmt)
 
@@ -29,12 +28,11 @@ class Checksum(object):
         if received != expected:
             log.warning('Invalid checksum: %08x != %08x', received, expected)
             raise ValueError('Invalid checksum')
-        else:
-            log.debug('Good checksum: %08x', received)
+        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)
@@ -88,7 +86,7 @@ def chain_wrapper(func):
     return wrapped
 
 
-class BitPacker(object):
+class BitPacker:
     byte_size = 8
 
     def __init__(self):

amodem/main.py

@@ -10,12 +10,12 @@ from . import framing, common, stream, detect, sampling
 log = logging.getLogger(__name__)
 
 
-def send(config, src, dst, gain=1.0):
+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)))
+    sender.write(np.zeros(int(Fs * (config.silence_start + extra_silence))))
 
     sender.start()
 
@@ -59,10 +59,11 @@ def recv(config, src, dst, dump_audio=None, pylab=None):
         gain = 1.0 / amplitude
         log.debug('Gain correction: %.3f', gain)
 
-        sampler = sampling.Sampler(signal, sampling.Interpolator(), freq=freq)
+        sampler = sampling.Sampler(signal, sampling.defaultInterpolator,
+                                   freq=freq)
         receiver.run(sampler, gain=1.0/amplitude, output=dst)
         return True
-    except BaseException:
+    except BaseException:  # pylint: disable=broad-except
         log.exception('Decoding failed')
         return False
     finally:

amodem/recv.py

@@ -13,7 +13,7 @@ from . import equalizer
 log = logging.getLogger(__name__)
 
 
-class Receiver(object):
+class Receiver:
 
     def __init__(self, config, pylab=None):
         self.stats = {}
@@ -43,9 +43,9 @@ class Receiver(object):
         self.plt.subplot(1, 2, 2)
         self.plt.plot(np.abs(S))
         self.plt.plot(equalizer.prefix)
-        errors = (bits != equalizer.prefix)
+        errors = bits != equalizer.prefix
         if any(errors):
-            msg = 'Incorrect prefix: {0} errors'.format(sum(errors))
+            msg = f'Incorrect prefix: {sum(errors)} errors'
             raise ValueError(msg)
         log.debug('Prefix OK')
 
@@ -70,6 +70,7 @@ 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]
@@ -80,7 +81,7 @@ 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)
@@ -93,8 +94,9 @@ class Receiver(object):
         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 _bitstream(self, symbols, error_handler):
         streams = []
@@ -109,7 +111,7 @@ class Receiver(object):
             bits = self.modem.decode(S, freq_handler)  # list of bit tuples
             streams.append(bits)  # bit stream per frequency
 
-        return common.izip(streams), symbol_list
+        return zip(*streams), symbol_list
 
     def _demodulate(self, sampler, symbols):
         symbol_list = []
@@ -156,6 +158,7 @@ class Receiver(object):
         )
 
     def run(self, sampler, gain, output):
+        log.debug('Receiving')
         symbols = dsp.Demux(sampler, omegas=self.omegas, Nsym=self.Nsym)
         self._prefix(symbols, gain=gain)
 
@@ -185,7 +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):

amodem/sampling.py

@@ -5,7 +5,7 @@ import numpy as np
 from . import common
 
 
-class Interpolator(object):
+class Interpolator:
 
     def __init__(self, resolution=1024, width=128):
 
@@ -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

amodem/send.py

@@ -10,7 +10,7 @@ from . import dsp
 log = logging.getLogger(__name__)
 
 
-class Sender(object):
+class Sender:
     def __init__(self, fd, config, gain=1.0):
         self.gain = gain
         self.offset = 0

amodem/stream.py

@@ -1,11 +1,11 @@
 import time
 
 
-class Reader(object):
+class Reader:
 
     wait = 0.2
     timeout = 2.0
-    bufsize = (8 << 10)
+    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:
@@ -45,7 +44,7 @@ class Reader(object):
     __next__ = next
 
 
-class Dumper(object):
+class Dumper:
     def __init__(self, src, dst):
         self.src = src
         self.dst = dst

amodem/tests/test_async_reader.py

@@ -1,7 +1,7 @@
 import mock
 import time
 import pytest
-from amodem import async
+from amodem import async_reader
 import logging
 
 logging.basicConfig(format='%(message)s')
@@ -13,7 +13,7 @@ def test_async_reader():
         return b'\x00' * n
     s = mock.Mock()
     s.read = _read
-    r = async.AsyncReader(s, 1)
+    r = async_reader.AsyncReader(s, 1)
 
     n = 5
     assert r.read(n) == b'\x00' * n
@@ -25,6 +25,6 @@ def test_async_reader():
 def test_async_reader_error():
     s = mock.Mock()
     s.read.side_effect = IOError()
-    r = async.AsyncReader(s, 1)
+    r = async_reader.AsyncReader(s, 1)
     with pytest.raises(IOError):
         r.read(3)

amodem/tests/test_calib.py

@@ -12,7 +12,7 @@ import mock
 config = config.fastest()
 
 
-class ProcessMock(object):
+class ProcessMock:
     def __init__(self):
         self.buf = BytesIO()
         self.stdin = self

amodem/tests/test_common.py

@@ -48,12 +48,6 @@ 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_configs():
     default = config.Configuration()
     fastest = config.fastest()

amodem/tests/test_stream.py

@@ -1,5 +1,6 @@
 from amodem import stream
 import subprocess as sp
+import sys
 
 script = br"""
 import sys
@@ -14,7 +15,7 @@ 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)

amodem/tests/test_transfer.py

@@ -49,13 +49,18 @@ def run(size, chan=None, df=0, success=True, cfg=None):
         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():

amodem/tests/utils.py

@@ -1,7 +1,7 @@
 import numpy as np
 
 
-class IIR(object):
+class IIR:
     def __init__(self, b, a):
         self.b = np.array(b) / a[0]
         self.a = np.array(a[1:]) / a[0]

setup.py

@@ -15,29 +15,28 @@ class PyTest(TestCommand):
 
 setup(
     name='amodem',
-    version='1.13.1',
+    version='1.15.4',
     description='Audio Modem Communication Library',
     author='Roman Zeyde',
-    author_email='roman.zeyde@gmail.com',
+    author_email='dev@romanzey.de',
     license='MIT',
     url='http://github.com/romanz/amodem',
     packages=['amodem'],
     tests_require=['pytest'],
     cmdclass={'test': PyTest},
-    install_requires=['numpy', 'six'],
+    install_requires=['numpy'],
     platforms=['POSIX'],
     classifiers=[
-        'Development Status :: 4 - Beta',
+        'Development Status :: 5 - Production/Stable',
         'Intended Audience :: Developers',
         'Intended Audience :: Information Technology',
         'License :: OSI Approved :: MIT License',
         'Operating System :: POSIX',
-        'Programming Language :: Python :: 2.7',
-        'Programming Language :: Python :: 3.2',
-        'Programming Language :: Python :: 3.3',
-        'Programming Language :: Python :: 3.4',
-        'Programming Language :: Python :: 3.5',
-        'Programming Language :: Python :: 3.6',
+        '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',
         'Topic :: Software Development :: Libraries :: Python Modules',
         'Topic :: System :: Networking',
         'Topic :: Communications',

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py27,py3
+envlist = py3
 [testenv]
 deps=
 	pytest
@@ -7,9 +7,8 @@ deps=
 	pycodestyle
 	coverage
 	pylint
-	six
 commands=
 	pycodestyle amodem/ scripts/
 	pylint --extension-pkg-whitelist=numpy --reports=no amodem --rcfile .pylintrc
-	coverage run --source amodem/ --omit="*/__main__.py" -m py.test -v
+	coverage run --source amodem/ --omit="*/__main__.py" -m pytest -v
 	coverage report