Use the blackbox logging rate to modify frequency

The frequency range on the analyser axis relates to the loop time but
also the logging rate;

Author: Gary Keeble

js/graph_spectrum.js

@@ -36,7 +36,7 @@ try {
 		source.start();
 
 	var spectrumAnalyser = audioCtx.createAnalyser();	  
-		spectrumAnalyser.fftSize = 512;
+		spectrumAnalyser.fftSize = 256;
 		spectrumAnalyser.smoothingTimeConstant = 0.8;
 		spectrumAnalyser.minDecibels = -100;
 		spectrumAnalyser.maxDecibels = -30;    
@@ -162,7 +162,7 @@ try {
 
 		  /* only plot the lower half of the FFT, as the top half
 		  never seems to have any values in it - too high frequency perhaps. */
-		  var PLOTTED_BUFFER_LENGTH = bufferLength / 2;
+		  var PLOTTED_BUFFER_LENGTH = bufferLength; // / 2;
 
 		  canvasCtx.translate(LEFT, TOP);
 
@@ -200,7 +200,7 @@ try {
 	function drawGridLines(sampleRate, LEFT, TOP, WIDTH, HEIGHT, MARGIN) {
 
 		var ticks = 5;
-		var frequencyInterval = (sampleRate / ticks) / 4;
+		var frequencyInterval = (sampleRate / ticks) / 2;
 		var frequency = 0;
 
 		for(var i=0; i<=ticks; i++) {
@@ -213,7 +213,7 @@ try {
 
 				canvasCtx.stroke();
 				var textAlign = (i==0)?'left':((i==ticks)?'right':'center');
-				drawAxisLabel((frequency)+"Hz", i * (WIDTH / ticks), HEIGHT + MARGIN, textAlign);
+				drawAxisLabel((frequency.toFixed(0))+"Hz", i * (WIDTH / ticks), HEIGHT + MARGIN, textAlign);
 				frequency += frequencyInterval;
 		}	
 	}

js/main.js

@@ -465,7 +465,11 @@ function BlackboxLogViewer() {
             analyserSampleRate:2000/*Hz*/,  // the loop time for the log
             };
 
-        if(flightLog.getSysConfig().loopTime        != null)    {graphOptions.analyserSampleRate = 1000000 / flightLog.getSysConfig().loopTime; }
+        if((flightLog.getSysConfig().loopTime             != null) &&
+            (flightLog.getSysConfig().frameIntervalPNum   != null) &&
+            (flightLog.getSysConfig().frameIntervalPDenom != null) ) {
+                graphOptions.analyserSampleRate = 1000000 / (flightLog.getSysConfig().loopTime * flightLog.getSysConfig().frameIntervalPDenom / flightLog.getSysConfig().frameIntervalPNum);
+                }
 
         graph = new FlightLogGrapher(flightLog, activeGraphConfig, canvas, craftCanvas, analyserCanvas, graphOptions);