Pause recording when signal is below squelch threshold

.gitignore

@@ -1,4 +1,6 @@
 *.pem
 *.crx
 *.zip
+*.bak
+*.db
 nacl-src/pnacl

README.md

@@ -1,8 +1,29 @@
+# Modifications in this fork:
+
+* Automatically pauses recording if signal is below the squelch threshold.
+
+* m key mutes audio instantly (recording is not affected). Adjust volute to resume.
+
+* Signal level is displayed with a bar. Hover mouse to read numerical value.
+
+* Clicking signal bar sets squelch level.
+
+* PgDn/PgUp moves through the list of saved preset stations.
+
+* Shift-PgDn begins (or ends) scanning through preset stations. Scanning stops when signal is above preset squelch level and resumes when signal drops below squelch level for a while.
+
+* Export/Import preset list includes the squelch setting for each station.
+
+* Clicking on the "Squelch" heading enters or leaves MONITOR mode, where squelch is temporarily set to zero to monitor frequency.
+
+* f/F key moves to the frequency display for editing (this is in the original help file, but didn't work).
+
+
 # Radio Receiver
 
 An application to listen to broadcast FM and AM radio from your Chrome browser or your ChromeBook computer using a $15 USB digital TV tuner.
 
-![Radio Receiver screenshot](image-src/interface.png)
+![Radio Receiver screenshot](image-src/interface2.png)
 
 ## What is this
 

extension/appconfig.js

@@ -34,7 +34,7 @@ function AppConfig() {
       /** Upconverter. */
       upconverter: {
         enable: false,
-        frequency: 125000000
+        frequency: 99999020 // Peter's up converter
       },
       /** Whether free tuning is enabled. */
       freeTuning: false

extension/audio.js

@@ -24,6 +24,8 @@ function Player() {
   var frameno = 0;
 
   var wavSaver = null;
+
+  var dampedLevel = 0;
 
   var ac = new (window.AudioContext || window.webkitAudioContext)();
   var gainNode = ac.createGain ? ac.createGain() : ac.createGainNode();
@@ -38,7 +40,10 @@ function Player() {
    */
   function play(leftSamples, rightSamples, level, squelch) {
     var buffer = ac.createBuffer(2, leftSamples.length, OUT_RATE);
-    if (level >= squelch) {
+    dampedLevel = 0.75 * dampedLevel + .25*level*100;
+    signalBar.value = Math.floor(dampedLevel);
+    signalBar.title = signalBar.value;
+    if ((dampedLevel/100) >= squelch) {
       buffer.getChannelData(0).set(leftSamples);
       buffer.getChannelData(1).set(rightSamples);
     }
@@ -50,7 +55,26 @@ function Player() {
         ac.currentTime + TIME_BUFFER);
     source.start(lastPlayedAt);
     if (wavSaver != null) {
-      wavSaver.writeSamples(leftSamples, rightSamples);
+       if ((dampedLevel/100) >= squelch) {
+         wavSaver.writeSamples(leftSamples, rightSamples);
+       }
+    }
+    if (typeof scanPresets == 'undefined') {         // proof of concept for preset scanning
+       scanPresets = false;                          // not likely to be the way it will be implemented
+       scanCount = 0;                                // a test to find the possible problems...
+    }
+    if (radio.requestingBlocks > 0) {
+       return;
+    }
+    if ( scanPresets ) {
+       scanCount++;
+       if ((dampedLevel/100) > squelch) {
+          scanCount = -5;                         // resume scanning after x+n no signal events
+       }
+       if ( scanCount > 5 && (level < squelch)) {  // scan every n events
+          interface.nextPreset();                  // tweak this parameter if too fast for dongle/decoder
+          scanCount = 0;
+       }
     }
   }
 
@@ -93,7 +117,7 @@ function Player() {
   function setVolume(volume) {
     gainNode.gain.value = volume;
   }
-
+  
   return {
     play: play,
     setVolume: setVolume,

extension/auxwindows.js

@@ -36,6 +36,7 @@ var AuxWindows = (function() {
         win.contentWindow['opener'] = window;
         var modeData = copyObject(band.getMode());
         modeData['step'] = band.getStep();
+        modeData['squelch'] = squelch;
         var stationData = {
           'frequency': frequency,
           'display': band.toDisplayName(frequency, true),
@@ -138,7 +139,7 @@ var AuxWindows = (function() {
           'width': 700,
           'height': 600
         },
-        'state': 'maximized',
+        'state': 'normal',
         'resizable': true
       });
   }

extension/help.html

@@ -69,6 +69,11 @@ <h2>Using presets</h2>
 <p>To switch to a preset, click the preset selection box (<b>7</b>) and choose your new preset. The radio will switch to it immediately.</p>
 <p>To delete a preset, switch to it and press the &ldquo;Remove&rdquo; button (<b>8</b>).</p>
 <p>To change a preset's name, switch to it and click the &ldquo;Save&rdquo; button (<b>6</b>). Type the new name and press &ldquo;Save&rdquo;.</p>
+<p>To export a set of presets for loading later, go to &ldquo;Settings&rdquo; (<b>12</b>) and
+click on the <a href="#settings">Manage your Presets</a> link.</p>
+<p>Use the <b>PgUp</b> and <b>PgDn</b> keys to select the previous or next preset station in the list.</p>
+<p>Hold down the <b>shift</b> key and press <b>PgDn</b> to begin automatic scanning of preset stations.
+The scan will pause if the squelch level is exceeded. Each preset can have its own squelch value assigned.</p>
 
 <h2>Changing volume and stereo</h2>
 <p>To change the volume, click on the &ldquo;loudspeaker&rdquo; icon (<b>9</b>) and move the slider left and right to decrease or increase the volume. You can also use your mouse wheel on the icon to change volume directly.</p>
@@ -101,7 +106,8 @@ <h2>Using Free Tuning</h2>
 
 <p>If you have <a href="#settings">configured an upconverter in the settings window</a> you can enable and disable it here by clicking the &ldquo;Upconverter&rdquo; field (<b>5</b>).</p>
 
-<p>The &ldquo;Squelch&rdquo; setting (<b>6</b>) lets you monitor a frequency without having to hear static when nobody is transmitting. The squelch level is the minimum strength level the signal must reach before you can hear it; if it's set to 0, you'll hear everything.</p>
+<p>The &ldquo;Squelch&rdquo; setting (<b>6</b>) lets you monitor a frequency without having to hear static when nobody is transmitting. The squelch level is the minimum strength level the signal must reach before you can hear it; if it's set to 0, you'll hear everything.
+Click on the signal strength display to set the squelch value slightly above the noise level.</p>
 
 <h1 id="settings">Settings</h1>
 <p>You can change a lot of settings by clicking on the &ldquo;wrench&rdquo; icon (<b>12</b>). There you can change several settings:</p>
@@ -124,8 +130,12 @@ <h1 id="shortcuts">Keyboard shortcuts</h1>
 <tr><td><tt>Space Bar</tt></td><td>Turn radio on/off</td></tr>
 <tr><td><tt>Up Arrow</tt></td><td>Volume Up</td></tr>
 <tr><td><tt>Down Arrow</tt></td><td>Volume Down</td></tr>
+<tr><td><tt>m</tt></td><td>Mute Volume</td></tr>
 <tr><td><tt>Left Arrow</tt></td><td>Decrease Frequency</td></tr>
 <tr><td><tt>Right Arrow</tt></td><td>Increase Frequency</td></tr>
+<tr><td><tt>PgUp</tt></td><td>Previous Preset</td></tr>
+<tr><td><tt>PgDn</tt></td><td>Next Preset</td></tr>
+<tr><td><tt>Shift-PgDn</tt></td><td>Scan Preset List</td></tr>
 <tr><td><tt>&lt;</tt></td><td>Scan for stations by decreasing frequency</td></tr>
 <tr><td><tt>&gt;</tt></td><td>Scan for stations by increasing frequency</td></tr>
 <tr><td><tt>f</tt></td><td>Edit frequency</td></tr>

extension/interface.css

@@ -367,6 +367,27 @@ option {
   width: 30px;
 }
 
+.signalDisplay {
+  bottom: 10px;
+  left: 10px;
+  width: 125px;
+}
+
+progress {
+  left: 0px;
+  width: 100px;
+  height: 15px;
+  border: 1px solid #afd;
+  background: #343;
+//  visibility: hidden;
+}
+progress::-webkit-progress-bar { 
+  background: #343; 
+}
+progress[value]::-webkit-progress-value {
+  background-image:  -webkit-linear-gradient(left, red 0%, orange 70%, yellow 90%, white 100%);
+}
+
 .freqMinusButton, .freqPlusButton {
   position: absolute;
   top: 0;

extension/interface.html

@@ -82,11 +82,12 @@
         <button id="upconverterDisplay" class="upconverterDisplay invisibleButton freeTuningButton" tabindex="16"></button>
       </div>
       <div id="squelchBox" class="squelchBox freeTuningBox">
-        <div class="freeTuningLabel">Squelch:</div>
+        <div class="freeTuningLabel" id="Squelch">Squelch:</div>
         <div id="squelchDisplay" class="squelchDisplay freeTuningDisplay">100</div>
         <input type="text" id="squelchInput" class="squelchInput freeTuningInput invisible" autocomplete="off" tabindex="17"></input>
       </div>
     </div>
+    <div id="signalDisplay" class="signalDisplay freeTuningDisplay"><progress id='signalBar' max='100' value='1'></progress></div>
   </div>
   <button id="freqPlusButton" class="freqPlusButton" title="Increase frequency" tabindex="23"><svg xmlns="http://www.w3.org/2000/svg" width="12" height="12" viewbox="0 0 12 12" version="1.1"><path d="M9.5,6l-5,5l-2,-2l3,-3l-3,-3l2,-2z" /></svg><br/>Freq+</button>  
   <button id="scanUpButton" class="scanUpButton" title="Scan increasing frequency" tabindex="25">Scan+<br/><svg xmlns="http://www.w3.org/2000/svg" width="12" height="12" viewbox="0 0 12 12" version="1.1"><path d="M5.5,6l-4,4l-1,-1l3,-3l-3,-3l1,-1z M11.5,6l-5,5l-2,-2l3,-3l-3,-3l2,-2z" /></svg></button>

extension/interface.js

@@ -33,7 +33,7 @@ function Interface(fmRadio) {
    * The current band configuration;
    */
   var currentBand = Bands['WW']['FM'];
-
+  var currentSquelch = 0;
   /**
    * Updates the UI.
    */
@@ -262,6 +262,12 @@ function Interface(fmRadio) {
   function changeVolumeUp() {
     setVolume(fmRadio.getVolume() + 0.1);
   }
+  /**
+   * Mute volume (change to 0).
+   */
+  function muteVolume() {
+    setVolume(0.0);
+  }
 
   /**
    * Changes volume with the mouse wheel.
@@ -684,6 +690,78 @@ function Interface(fmRadio) {
     saveSettings();
     update();
   }
+
+  /**
+   * Monitor - open squelch by clicking on "Squelch:" to monitor frequency
+   *           Click again on "MONITOR" to resume stored squelch setting
+   */
+
+  function squelchClick() {
+     var mode = appConfig.state.mode.get();
+     if ( Squelch.textContent == 'Squelch:') {
+        currentSquelch = mode.params.squelch;
+        fmRadio.setSquelch(0);
+        squelchDisplay.hidden = true;
+        Squelch.textContent = 'MONITOR';
+     } else {
+        fmRadio.setSquelch(currentSquelch);
+        Squelch.textContent = 'Squelch:';
+        squelchDisplay.hidden = false;
+     }
+  }
+
+
+  /**
+   * Change squelch by clicking on signal strength display.
+   */
+
+   function clickChangeSquelch(value){
+     changeSquelch(value.offsetX);
+     }
+
+     /**
+      * Selects the previous preset in the list.
+      */
+
+   function prevPreset(shiftKey){
+       if ( presetsBox.length < 3 ) { return; }
+       signalBar.value = 0;
+       if ( presetsBox[0].selected || presetsBox[1].selected ) {
+          presetsBox[presetsBox.length-1].selected = true;
+          selectPreset();
+       } else {
+          for (i = 0; i < presetsBox.length; i++){
+             if ( presetsBox[i].selected ){
+                presetsBox[i-1].selected = true;
+                selectPreset();
+                break;
+             }
+          }
+       }
+     }
+
+  /**
+   * Selects the next preset in the list.
+   */
+   function nextPreset(shiftKey){
+       if ( presetsBox.length < 3 ) { return; }
+       if ( shiftKey ) {
+          scanPresets = ! scanPresets;
+       }
+       signalBar.value = 0;
+       if ( presetsBox[presetsBox.length-1].selected ) {
+          presetsBox[1].selected = true;
+          selectPreset();
+       } else {
+          for (i = 0; i < presetsBox.length; i++){
+             if ( presetsBox[i].selected ){
+                presetsBox[i+1].selected = true;
+                selectPreset();
+                break;
+             }
+          }
+       }
+     }
 
   /**
    * Closes the window.
@@ -777,6 +855,12 @@ function Interface(fmRadio) {
     }
     if (e.type == 'keydown') {
       switch (e.keyCode) {
+        case 33:   // PgUp
+          prevPreset(e.shiftKey);
+          break;
+        case 34:   // PgDn
+          nextPreset(e.shiftKey);
+          break;
         case 37:
           frequencyMinus();
           break;
@@ -809,8 +893,13 @@ function Interface(fmRadio) {
         case 98:  // b
           switchBand();
           break;
+        case  70: // F
         case 102: // f
-          showFrequencyEditor();
+          frequencyDisplay.click(); 
+          break;
+        case 77:  // M
+        case 109: // m
+          muteVolume();
           break;
         case 80:  // P
         case 112: // p
@@ -905,6 +994,7 @@ function Interface(fmRadio) {
     upconverterDisplay.addEventListener('click', toggleUpconverter);
     attachDisplayInputEvents(squelchDisplay, squelchInput, changeSquelch);
     squelchDisplay.addEventListener('mousewheel', changeSquelchWheel);
+    signalDisplay.addEventListener('click', clickChangeSquelch);
     freqMinusButton.addEventListener('click', frequencyMinus);
     freqPlusButton.addEventListener('click', frequencyPlus);
     scanDownButton.addEventListener('click', scanDown);
@@ -917,6 +1007,7 @@ function Interface(fmRadio) {
     window.addEventListener('message', getMessage);
     window.addEventListener('keydown', handleShortcut);
     window.addEventListener('keypress', handleShortcut);
+    Squelch.addEventListener('mousedown',squelchClick);
     fmRadio.setInterface(this);
     fmRadio.setOnError(showErrorWindow);
     loadSettings(function() {
@@ -928,6 +1019,7 @@ function Interface(fmRadio) {
 
   return {
     attach: attach,
+    nextPreset: nextPreset,
     update: update
   };
 }

extension/presetmanager.js

@@ -80,7 +80,7 @@ function showPresets(table, presets, delPresets, precheck) {
     var isDouble = preset && delPreset;
     var line;
     if (delPreset) {
-      line = makePresetLine(value, delPreset, i, true, isDouble, precheck);
+      line = makePresetLine(value, delPreset, i, true, isDouble, true);
       table.firstElementChild.appendChild(line);
     }
     if (preset) {
@@ -173,6 +173,9 @@ function makeModeCell(preset) {
     if (mode['upconvert']) {
       text += '; upconvert=on';
     }
+    if (mode['squelch']) {
+      text += '; squelch='+mode['squelch'];
+    }
   }
   td.appendChild(document.createTextNode(text));
   return td;

extension/radiocontroller.js

@@ -155,6 +155,10 @@ function RadioController() {
   function getSquelch() {
     return squelch;
   }
+
+  function getRB() {
+    return requestingBlocks;
+  }
 
   /**
    * Searches a given frequency band for a station, starting at the
@@ -686,6 +690,8 @@ function RadioController() {
     stopRecording: stopRecording,
     isRecording: isRecording,
     setInterface: setInterface,
-    setOnError: setOnError
+    setOnError: setOnError,
+    requestingBlocks: getRB
+
   };
 }