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@ -1,11 +1,23 @@ |
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/* ReceiverFM.ino Bob Larkin 26 April 2020
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* This is a simple test of introducing a sine wave to the |
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/* ReceiverFM.ino Bob Larkin 26 April 2020
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* No copyright. |
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*
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* This INO runs the FM detector on input data from the Codec. It |
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* requires an FM modulated signal source at 15 kHz. The Serial out is |
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* the squelch level generated by the squelch noise detector. |
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*
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* Commented out is a test of introducing a sine wave to the |
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* FM Detector and taking 512 samples of the output. It is |
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* a static test with a fixed frequency for test and so |
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* the output DC value and noise can be tested. Note that the 512 |
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* samples include the startup transient, so the first 300,
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* or so, points should be ignored in seeing the DC value. |
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*
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* An option is to change the squelch noise filter (commented out) |
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* and this serves as an example of changing the 10 coefficients. |
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*
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* Another commented out loop code will print the observed spectrum using |
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* the 1024 point FFT. This shows the NBFM de-emphasis curve. |
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*
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* Change the value of sine1.frequency to see the DC output change. |
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* See FMReceiver2.ino for testing with real AC modulation. |
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*
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@ -22,32 +34,32 @@ |
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#define SINE_ADC 0 |
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#if SINE_ADC |
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AudioSynthGaussian_F32 gwn1; |
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AudioSynthWaveformSine_F32 sine1; |
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AudioMixer4_F32 mix1; |
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RadioFMDetector_F32 fmDet1; |
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AudioOutputI2S_F32 i2sOut; |
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AudioAnalyzeFFT1024_F32 fft1; |
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AudioRecordQueue_F32 queue1; |
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AudioConvert_F32toI16 cnvrtOut; |
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AudioOutputI2S i2sOut; |
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AudioControlSGTL5000 sgtl5000_1; |
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AudioConnection_F32 connect1(sine1, 0, fmDet1, 0); |
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AudioConnection_F32 connect3(fmDet1, 0, cnvrtOut, 0); |
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AudioConnection connect4(cnvrtOut, 0, i2sOut, 0); // left
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AudioConnection_F32 connect5(fmDet1, 0, queue1, 0); |
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AudioConnection_F32 connectA(gwn1, 0, mix1, 0); |
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AudioConnection_F32 connectB(sine1, 0, mix1, 1); |
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AudioConnection_F32 connectC(mix1, 0, fmDet1, 0); |
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#else // Input from Teensy Audio Adaptor SGTL5000
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// Note - With no input, the FM detector output is all noise. This
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// can be loud, so one can add a gain block at the fmDet1 output (like 0.05 gain).
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AudioInputI2S i2sIn; |
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AudioConvert_I16toF32 cnvrtIn; |
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RadioFMDetector_F32 fmDet1; |
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AudioRecordQueue_F32 queue1;
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AudioConvert_F32toI16 cnvrtOut; |
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AudioOutputI2S i2sOut; |
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AudioControlSGTL5000 sgtl5000_1; |
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AudioConnection connect1(i2sIn, 0, cnvrtIn, 0); // left
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AudioConnection_F32 connect2(cnvrtIn, 0, fmDet1, 0); |
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AudioConnection_F32 connect3(fmDet1, 0, cnvrtOut, 0); |
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AudioConnection_F32 connect5(fmDet1, 0, queue1, 0); |
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AudioConnection connect7(cnvrtOut, 0, i2sOut, 0); |
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// can be loud, so lower the gain below (like 0.05 gain).
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AudioInputI2S_F32 i2sIn; |
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RadioFMDetector_F32 fmDet1; |
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AudioAnalyzeFFT1024_F32 fft1; |
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AudioRecordQueue_F32 queue1;
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AudioOutputI2S_F32 i2sOut; |
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AudioControlSGTL5000 sgtl5000_1; |
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AudioConnection_F32 connectD(i2sIn, 0, fmDet1, 0); // left
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#endif |
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// Common for both input sources
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AudioConnection_F32 connect1(fmDet1, 1, i2sOut, 0); // Squelched
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AudioConnection_F32 connect2(fmDet1, 0, fft1, 0); |
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AudioConnection_F32 connect3(fmDet1, 0, queue1, 0); |
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float dt1[512]; // Place to save output
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float *pq1, *pd1; |
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@ -56,17 +68,22 @@ int i; |
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void setup(void) { |
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AudioMemory(5); |
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AudioMemory_F32(5); |
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Serial.begin(300); delay(1000); // Any rate is OK
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AudioMemory_F32(100); |
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Serial.begin(300); delay(500); // Any rate is OK
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Serial.println("Serial Started"); |
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sgtl5000_1.enable(); |
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sgtl5000_1.inputSelect(AUDIO_INPUT_LINEIN);
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#if SINE_ADC |
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sine1.frequency(14000.0); |
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sine1.frequency(15000.0); |
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sine1.amplitude(0.0001f); |
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gwn1.amplitude(0.1f); |
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#endif |
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fft1.setOutputType(FFT_DBFS); |
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fft1.setNAverage(10); |
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// The FM detector has error checking during object construction
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// when Serial.print is not available. See RadioFMDetector_F32.h:
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Serial.print("FM Initialization errors: "); |
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@ -76,30 +93,59 @@ void setup(void) { |
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// Output goes to the Serial (USB) Monitor. Normally, this is quiet.
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fmDet1.showError(1); |
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fmDet1.setSquelchThreshold(0.7f); |
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// Here is an example of designing and using a non-default squelch
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// noise filter. The INO provides storage for the new coefficients.
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// static float newFilter[10];
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// freq Q ptr to Coeff
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// setBandpassBiQuad(2000.0f, 3.0f, &newFilter[0]);
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// setBandpassBiQuad(4000.0f, 3.0f, &newFilter[5]);
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// fmDet1.setSquelchFilter(newFilter);
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// Set the volume control (0.0 to 1.0)
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i2sOut.setGain(0.05f); |
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queue1.begin();
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i = 0; k=0; |
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} |
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void loop(void) { |
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float lData[512]; |
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Serial.print("sqLevel "); Serial.println(fmDet1.getSquelchLevel(), 6); |
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delay(500); |
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/*
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if( fft1.available() ) { |
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float* pd = fft1.getData(); |
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for(int k=0; k<512; k++) |
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lData[k] = pd[k]; |
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for(int k=0; k<512; k++) |
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Serial.println(lData[k],3); |
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Serial.println(" -------"); |
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} |
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*/ |
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/*
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// Collect 512 samples and output to Serial
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// This "if" will be active for i = 0,1,2,3
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if (queue1.available() >= 1) { |
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if( i>=0 && i<4) { |
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pq1 = queue1.readBuffer(); |
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pd1 = &dt1[i*128]; |
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for(k=0; k<128; k++) { |
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*pd1++ = *pq1++;
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} |
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for(k=0; k<128; k++) |
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*pd1++ = *pq1++;
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queue1.freeBuffer(); |
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if(i++==3) { |
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i=4; // Only collect 4 blocks
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queue1.end(); // No more data to queue1
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} |
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} |
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} |
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else { |
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queue1.freeBuffer(); |
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} |
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} |
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} |
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// We have 512 data samples. Serial.print them
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if(i == 4) { |
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#if SINE_ADC |
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@ -111,9 +157,9 @@ void loop(void) { |
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Serial.print (0.000022667*(float32_t)k, 6); Serial.print (", "); |
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Serial.print (dt1[k],7); Serial.print (", "); |
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Serial.println (dt1[k]/0.000142421, 2); // Convert to Hz
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} |
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} |
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i = 5; |
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} |
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} |
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if(i==5) { |
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i = 6; |
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Serial.print("CPU: Percent Usage, Max: "); |
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@ -131,5 +177,22 @@ void loop(void) { |
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Serial.print(", "); |
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Serial.println(AudioMemoryUsageMax_F32()); |
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Serial.println(); |
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} |
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*/ |
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} |
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} |
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// Find BiQuad Coefficients for Squelch Noise filter.
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// Only used if the default -6 dB points of 2680 and 4420 Hz
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// are not suitable
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void setBandpassBiQuad(float frequency, float q, float* cf) { |
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double w0 = frequency * (2 * 3.141592654 / 44100); // sampleRate_Hz);
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double sinW0 = sin(w0); |
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double alpha = sinW0 / ((double)q * 2.0); |
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double cosW0 = cos(w0); |
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double scale = 1.0 / (1.0+alpha); |
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/* b0 */ cf[0] = alpha * scale; |
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/* b1 */ cf[1] = 0; |
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/* b2 */ cf[2] = (-alpha) * scale; |
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/* a1 */ cf[3] = -(-2.0 * cosW0) * scale; |
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/* a2 */ cf[4] = -(1.0 - alpha) * scale; |
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} |
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boblark
4 years ago