From ab2ac347e0c3186a41ad13f0d50a33548783e7bf Mon Sep 17 00:00:00 2001
From: Lewis Moten <lewismoten@gmail.com>
Date: Mon, 6 May 2024 04:14:54 -0400
Subject: [PATCH] channel frequency resolution padding

---
 index.html |  1 +
 index.js   | 22 ++++++++++++++--------
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/index.html b/index.html
index b5f0d88..39ece69 100644
--- a/index.html
+++ b/index.html
@@ -67,6 +67,7 @@
       FFT Size: 2^<input id="fft-size-power-text" type="number" min="5" max="15" value="90"><br>
       Frequency Resolution Multiplier: <input id="frequency-resolution-multiplier" type="number" min="1" max="20"
         value="2"><br>
+      Channel Frequency Resolution Padding: <input id="channel-frequency-resolution-padding" type="number" min="0" max="20"><br>
       Smoothing Time Constant: <input id="smoothing-time-constant-text" type="number" min="0.00" max="1.00" step="0.01"
         value="0.00"><br>
       <label>
diff --git a/index.js b/index.js
index 849a7fb..db40605 100644
--- a/index.js
+++ b/index.js
@@ -10,21 +10,22 @@ var receivedDataTextarea;
 var sentDataTextArea;
 var receivedGraph;
 var receivedData = [];
-var MAX_DATA = 300;
+var MAX_AMPLITUDE = 300; // Higher than 255 to give us space
 var pauseTimeoutId;
 var sampleIntervalIds = [];
 
 var TEXT_TO_SEND = "U";
 var RANDOM_COUNT = 128;
-var MAX_BITS_DISPLAYED_ON_GRAPH = 78;
+var MAX_BITS_DISPLAYED_ON_GRAPH = 79;
 var SEGMENT_DURATION = 30;
 var AMPLITUDE_THRESHOLD_PERCENT = .75;
 var AMPLITUDE_THRESHOLD = 160;
-var MINIMUM_FREQUENCY = 304;
-var MAXIMUM_FREQUENCY = 4800;
+var MINIMUM_FREQUENCY = 323;
+var MAXIMUM_FREQUENCY = 9226;
 var LAST_SEGMENT_PERCENT = 0.6;
 var FFT_SIZE_POWER = 10;
 var FREQUENCY_RESOLUTION_MULTIPLIER = 2;
+let CHANNEL_FREQUENCY_RESOLUTION_PADDING = 2;
 var SMOOTHING_TIME_CONSTANT = 0;
 var HAMMING_ERROR_CORRECTION = true;
 
@@ -91,6 +92,11 @@ function handleWindowLoad() {
     FREQUENCY_RESOLUTION_MULTIPLIER = parseInt(event.target.value);
     showSpeed();
   })
+  document.getElementById('channel-frequency-resolution-padding').value = CHANNEL_FREQUENCY_RESOLUTION_PADDING;
+  document.getElementById('channel-frequency-resolution-padding').addEventListener('input', event => {
+    CHANNEL_FREQUENCY_RESOLUTION_PADDING = parseInt(event.target.value);
+    showSpeed();
+  })
   document.getElementById('bit-duration-text').addEventListener('input', (event) => {
     SEGMENT_DURATION = parseInt(event.target.value);
     bitSampleCount = 0;
@@ -310,7 +316,7 @@ function getChannels() {
   const fftSize = 2 ** FFT_SIZE_POWER;
   const frequencyResolution = sampleRate / fftSize;
   const channels = [];
-  const pairStep = frequencyResolution * 2 * FREQUENCY_RESOLUTION_MULTIPLIER;
+  const pairStep = frequencyResolution * (2 + CHANNEL_FREQUENCY_RESOLUTION_PADDING) * FREQUENCY_RESOLUTION_MULTIPLIER;
   for(let hz = MINIMUM_FREQUENCY; hz < MAXIMUM_FREQUENCY; hz+= pairStep) {
     const low = Math.floor(hz);
     const high = Math.floor(hz + frequencyResolution * FREQUENCY_RESOLUTION_MULTIPLIER);
@@ -952,7 +958,7 @@ function drawFrequencyLineGraph(ctx, channel, highLowIndex, color, lineWidth, da
     if(x === -1) continue;
     if(channel > pairs.length) continue;
     const amplitude = pairs[channel][highLowIndex];
-    const y = getPercentY(amplitude / MAX_DATA);
+    const y = getPercentY(amplitude / MAX_AMPLITUDE);
     if(i === 0) ctx.moveTo(x, y); else ctx.lineTo(x, y);
   }
   if(isSelected || isOver) {
@@ -980,7 +986,7 @@ function drawFrequencyDots(ctx, channel, highLowIndex, color) {
     const x = getTimeX(time, newest);
     if(x === -1) continue;
     const amplitude = pairs[channel][highLowIndex];
-    const y = getPercentY(amplitude / MAX_DATA);
+    const y = getPercentY(amplitude / MAX_AMPLITUDE);
 
     ctx.beginPath();
     ctx.arc(x, y, radius, 0, fullCircle);
@@ -1269,7 +1275,7 @@ function drawFrequencyData(forcedDraw) {
   ctx.fillStyle = 'black';
   ctx.fillRect(0, 0, width, height);
   
-  const thresholdY = (1 - (AMPLITUDE_THRESHOLD/MAX_DATA)) * height;
+  const thresholdY = (1 - (AMPLITUDE_THRESHOLD/MAX_AMPLITUDE)) * height;
   ctx.strokeStyle = 'grey';
   ctx.beginPath();
   ctx.moveTo(0, thresholdY);