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FFT256iq corrected windowing subscripts, added xAxis fcn, nAve

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pull/6/merge
boblark 3 years ago
parent c621d6cb0d
commit 10b56112d1
3 changed files with 159 additions and 57 deletions
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  1. 78
      analyze_fft256_iq_F32.cpp
  2. 81
      analyze_fft256_iq_F32.h
  3. 57
      examples/TestFFT256iq/TestFFT256iq.ino

78
analyze_fft256_iq_F32.cpp
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@ -39,15 +39,13 @@
#include "analyze_fft256_iq_F32.h" #include "analyze_fft256_iq_F32.h"
// Move audio data from audio_block_f32_t to the interleaved FFT instance buffer. // Move audio data from audio_block_f32_t to the interleaved FFT instance buffer.
static void copy_to_fft_buffer1(void *destination, const void *sourceI, const void *sourceQ) { static void copy_to_fft_buffer0(void *destination, const void *sourceI, const void *sourceQ) {
const float *srcI = (const float *)sourceI; const float *srcI = (const float *)sourceI;
const float *srcQ = (const float *)sourceQ; const float *srcQ = (const float *)sourceQ;
float *dst = (float *)destination; float *dst = (float *)destination;
for (int i=0; i < AUDIO_BLOCK_SAMPLES; i++) { for (int i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
*dst++ = *srcI++; // real sample, interleave *dst++ = *srcI++; // real sample, interleave
//*dst++ = 0.0f;
*dst++ = *srcQ++; // imag *dst++ = *srcQ++; // imag
//*dst++ = 0.0f;
} }
} }
@ -55,13 +53,14 @@ static void apply_window_to_fft_buffer1(void *fft_buffer, const void *window) {
float *buf = (float *)fft_buffer; // 0th entry is real (do window) 1th is imag float *buf = (float *)fft_buffer; // 0th entry is real (do window) 1th is imag
const float *win = (float *)window; const float *win = (float *)window;
for (int i=0; i < 256; i++) { for (int i=0; i < 256; i++) {
buf[2*i] *= *win++; // real buf[2*i] *= *win; // real
buf[2*i + 1] *= *win++; // imag buf[2*i + 1] *= *win++; // imag
} }
} }
void AudioAnalyzeFFT256_IQ_F32::update(void) { void AudioAnalyzeFFT256_IQ_F32::update(void) {
audio_block_f32_t *block_i,*block_q; audio_block_f32_t *block_i,*block_q;
int ii;
block_i = receiveReadOnly_f32(0); block_i = receiveReadOnly_f32(0);
if (!block_i) return; if (!block_i) return;
@ -78,40 +77,67 @@ void AudioAnalyzeFFT256_IQ_F32::update(void) {
prevblock_q = block_q; prevblock_q = block_q;
return; // Nothing to release return; // Nothing to release
} }
// FFT is 256 and blocks are 128, so we need 2 blocks. We still do // FFT is 256 and blocks are 128, so we need 2 blocks. We still do
// this every 128 samples to get 50% overlap on FFT data to roughly // this every 128 samples to get 50% overlap on FFT data to roughly
// compensate for windowing. // compensate for windowing.
// ( dest, i-source, q-source ) // ( dest, i-source, q-source )
copy_to_fft_buffer1(fft_buffer, prevblock_i->data, prevblock_q->data); copy_to_fft_buffer0(fft_buffer, prevblock_i->data, prevblock_q->data);
copy_to_fft_buffer1(fft_buffer+256, block_i->data, block_q->data); copy_to_fft_buffer0(fft_buffer+256, block_i->data, block_q->data);
if (pWin) if (pWin)
apply_window_to_fft_buffer1(fft_buffer, window); apply_window_to_fft_buffer1(fft_buffer, window);
arm_cfft_radix4_f32(&fft_inst, fft_buffer); // Finally the FFT
#if defined(__IMXRT1062__)
// Teensyduino core for T4.x supports arm_cfft_f32
// arm_cfft_f32 (const arm_cfft_instance_f32 *S, float32_t *p1, uint8_t ifftFlag, uint8_t bitReverseFlag)
arm_cfft_f32(&Sfft, fft_buffer, 0, 1);
#else
// For T3.x go back to old (deprecated) style
arm_cfft_radix4_f32(&fft_inst, fft_buffer);
#endif
count++; count++;
for (int i=0; i < 256; i++) { for (int i = 0; i < 128; i++) {
float ss = fft_buffer[2*i]*fft_buffer[2*i] + fft_buffer[2*i+1]*fft_buffer[2*i+1]; // From complex FFT the "negative frequencies" are mirrors of the frequencies above fs/2. So, we get
if(count==1) // Starting new average // frequencies from 0 to fs by re-arranging the coefficients. These are powers (not Volts)
sumsq[i] = ss; // See DD4WH SDR (Note - here and at "if(xAxis & xxxx)" below, we may have redundancy in index changing.
else if (count <= nAverage) // Adding on to average // Leave as is for now.)
sumsq[i] += ss; float ss0 = fft_buffer[2 * i] * fft_buffer[2 * i] +
fft_buffer[2 * i + 1] * fft_buffer[2 * i + 1];
float ss1 = fft_buffer[2 * (i + 128)] * fft_buffer[2 * (i + 128)] +
fft_buffer[2 * (i + 128) + 1] * fft_buffer[2 * (i + 128) + 1];
if(count==1) { // Starting new average
sumsq[i+128] = ss0;
sumsq[i] = ss1;
}
else if (count <= nAverage) { // Adding on to average
sumsq[i+128] += ss0;
sumsq[i] += ss1;
}
} }
if (count >= nAverage) { // Average is finished if (count >= nAverage) { // Average is finished
count = 0; count = 0;
float inAf = 1.0f/(float)nAverage; float inAf = 1.0f/(float)nAverage;
for (int i=0; i < 256; i++) { for (int i=0; i < 256; i++) {
int ii = 255 - (i ^ 128); // xAxis, bit 0 left/right; bit 1 low to high
if(outputType==FFT_RMS) if(xAxis & 0X02)
output[ii] = sqrtf(inAf*sumsq[ii]); ii = i;
else if(outputType==FFT_POWER) else
output[ii] = inAf*sumsq[ii]; ii = i^128;
else if(outputType==FFT_DBFS) if(xAxis & 0X01)
output[ii] = 10.0f*log10f(inAf*sumsq[ii])-42.1442f; // Scaled to FS sine wave ii = (255 - ii);
else if(outputType==FFT_RMS)
output[ii] = 0.0f; output[i] = sqrtf(inAf*sumsq[ii]);
} else if(outputType==FFT_POWER)
output[i] = inAf*sumsq[ii];
else if(outputType==FFT_DBFS)
output[i] = 10.0f*log10f(inAf*sumsq[ii])-42.1442f; // Scaled to FS sine wave
else
output[i] = 0.0f;
} }
}
outputflag = true; outputflag = true;
release(prevblock_i); // Release the 2 blocks that were block_i release(prevblock_i); // Release the 2 blocks that were block_i
release(prevblock_q); // and block_q on last time through update() release(prevblock_q); // and block_q on last time through update()

81
analyze_fft256_iq_F32.h
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@ -1,15 +1,27 @@
/* analyze_fft256_iq_F32.h /* analyze_fft256_iq_F32.h Assembled by Bob Larkin 6 Mar 2021
* *
* Converted to F32 floating point input and also extended * Rev 6 Mar 2021 - Added setXAxis()
* for complex I and Q inputs * Rev 7 Mar 2021 - Corrected bug in applying windowing
* * Adapted all I/O to be F32 floating point for OpenAudio_ArduinoLibrary *
* * Future: Add outputs for I & Q FFT x2 for overlapped FFT * Does Fast Fourier Transform of a 256 point complex (I-Q) input.
* Output is one of three measures of the power in each of the 256
* output bins, Power, RMS level or dB relative to a full scale
* sine wave. Windowing of the input data is provided for to reduce
* spreading of the power in the output bins. All inputs are Teensy
* floating point extension (_F32) and all outputs are floating point.
*
* Features include:
* * I and Q inputs are OpenAudio_Arduino Library F32 compatible.
* * FFT output for every 128 inputs to overlapped FFTs to
* compensate for windowing.
* * Windowing None, Hann, Kaiser and Blackman-Harris. * * Windowing None, Hann, Kaiser and Blackman-Harris.
* * Multiple bin-sum output to simulate wider bins.
* * Power averaging of multiple FFT
* * Soon: F32 audio outputs for I & Q
* *
* Conversion Copyright (c) 2021 Bob Larkin * Conversion Copyright (c) 2021 Bob Larkin
* Same MIT license as PJRC: * Same MIT license as PJRC:
* *
*
* Audio Library for Teensy 3.X * Audio Library for Teensy 3.X
* Copyright (c) 2014, Paul Stoffregen, paul@pjrc.com * Copyright (c) 2014, Paul Stoffregen, paul@pjrc.com
* *
@ -36,8 +48,8 @@
* THE SOFTWARE. * THE SOFTWARE.
*/ */
/* Does complex input FFT of 1024 points. Output is not audio, and is magnitude /* Does complex input FFT of 256 points. Multiple non-audio (via functions)
* only. Multiple output formats of RMS (same as I16 version, and default), * output formats of RMS (same as I16 version, and default),
* Power or dBFS (full scale). Output can be bin by bin or a pointer to * Power or dBFS (full scale). Output can be bin by bin or a pointer to
* the output array is available. Several window functions are provided by * the output array is available. Several window functions are provided by
* in-class design, or a custom window can be provided from the INO. * in-class design, or a custom window can be provided from the INO.
@ -51,7 +63,17 @@
* float* getData(void) * float* getData(void)
* float* getWindow(void) * float* getWindow(void)
* void putWindow(float *pwin) * void putWindow(float *pwin)
* void setNAverage(int NAve) // >=1
* void setOutputType(int _type) * void setOutputType(int _type)
* void setXAxis(uint8_t _xAxis) // 0, 1, 2, 3
*
* x-Axis direction and offset per setXAxis(xAxis) for sine to I
* and cosine to Q.
* If xAxis=0 f=fs/2 in middle, f=0 on right edge
* If xAxis=1 f=fs/2 in middle, f=0 on left edge
* If xAxis=2 f=fs/2 on left edge, f=0 in middle
* If xAxis=3 f=fs/2 on right edgr, f=0 in middle
* If there is 180 degree phase shift to I or Q these all get reversed.
* *
* Timing, max is longest update() time: * Timing, max is longest update() time:
* T3.6 Windowed, RMS out, - uSec max * T3.6 Windowed, RMS out, - uSec max
@ -75,13 +97,13 @@
#ifndef analyze_fft256iq_h_ #ifndef analyze_fft256iq_h_
#define analyze_fft256iq_h_ #define analyze_fft256iq_h_
//#include "AudioStream.h"
//#include "arm_math.h"
#include "Arduino.h" #include "Arduino.h"
#include "AudioStream_F32.h" #include "AudioStream_F32.h"
#include "arm_math.h" #include "arm_math.h"
#include "mathDSP_F32.h" #include "mathDSP_F32.h"
#if defined(__IMXRT1062__)
#include "arm_const_structs.h"
#endif
#define FFT_RMS 0 #define FFT_RMS 0
#define FFT_POWER 1 #define FFT_POWER 1
@ -97,10 +119,21 @@ class AudioAnalyzeFFT256_IQ_F32 : public AudioStream_F32 {
//GUI: inputs:2, outputs:4 //this line used for automatic generation of GUI node //GUI: inputs:2, outputs:4 //this line used for automatic generation of GUI node
//GUI: shortName:AnalyzeFFT256IQ //GUI: shortName:AnalyzeFFT256IQ
public: public:
AudioAnalyzeFFT256_IQ_F32() : AudioStream_F32(2, inputQueueArray) { // NEEDS SETTINGS etc <<<<<<<< AudioAnalyzeFFT256_IQ_F32() : AudioStream_F32(2, inputQueueArray) {
arm_cfft_radix4_init_f32(&fft_inst, 256, 0, 1); // __MK20DX128__ T_LC; __MKL26Z64__ T3.0; __MK20DX256__T3.1 and T3.2
// __MK64FX512__) T3.5; __MK66FX1M0__ T3.6; __IMXRT1062__ T4.0 and T4.1
#if defined(__IMXRT1062__)
// Teensy4 core library has the right files for new FFT
// arm CMSIS library has predefined structures of type arm_cfft_instance_f32
Sfft = arm_cfft_sR_f32_len256; // This is one of the structures
#else
arm_cfft_radix4_init_f32(&fft_inst, 256, 0, 1); // for T3.x
#endif
useHanningWindow(); useHanningWindow();
} }
// There is no varient for "settings," as blocks other than 128 are
// not supported and, nothing depends on sample rate so we don't need that.
bool available() { bool available() {
if (outputflag == true) { if (outputflag == true) {
@ -181,7 +214,18 @@ public:
outputType = _type; outputType = _type;
} }
virtual void update(void); // Output power (non-coherent) averaging
// i.e., the number of FFT powers averaged in the output
void setNAverage(int _nAverage) {
nAverage = _nAverage;
}
// xAxis, bit 0 left/right; bit 1 low to high; default 0X03
void setXAxis(uint8_t _xAxis) {
xAxis = _xAxis;
}
virtual void update(void);
private: private:
float output[256]; float output[256];
@ -193,10 +237,17 @@ private:
bool outputflag = false; bool outputflag = false;
audio_block_f32_t *inputQueueArray[2]; audio_block_f32_t *inputQueueArray[2];
audio_block_f32_t *prevblock_i,*prevblock_q; audio_block_f32_t *prevblock_i,*prevblock_q;
#if defined(__IMXRT1062__)
// For T4.x
// const static arm_cfft_instance_f32 arm_cfft_sR_f32_len256;
arm_cfft_instance_f32 Sfft;
#else
arm_cfft_radix4_instance_f32 fft_inst; arm_cfft_radix4_instance_f32 fft_inst;
#endif
int outputType = FFT_RMS; //Same type as I16 version init int outputType = FFT_RMS; //Same type as I16 version init
int count = 0; int count = 0;
int nAverage = 1; int nAverage = 1;
uint8_t xAxis = 3;
// The Hann window is a good all-around window // The Hann window is a good all-around window
void useHanningWindow(void) { void useHanningWindow(void) {
@ -238,8 +289,6 @@ private:
kbes = 1.0f / mathEqualizer.i0f(beta); // An additional derived parameter used in loop kbes = 1.0f / mathEqualizer.i0f(beta); // An additional derived parameter used in loop
for (int n=0; n<128; n++) { for (int n=0; n<128; n++) {
xn2 = 0.5f+(float32_t)n; xn2 = 0.5f+(float32_t)n;
// 4/(1023^2)=0.00000382215877f
// xn2 = 0.00000382215877f*xn2*xn2;
// 4/(255^2)=0.000061514802f // 4/(255^2)=0.000061514802f
xn2 = 0.000061514802f*xn2*xn2; xn2 = 0.000061514802f*xn2*xn2;
window[127 - n]=kbes*(mathEqualizer.i0f(beta*sqrtf(1.0-xn2))); window[127 - n]=kbes*(mathEqualizer.i0f(beta*sqrtf(1.0-xn2)));

57
examples/TestFFT256iq/TestFFT256iq.ino
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@ -10,12 +10,11 @@
#include <SerialFlash.h> #include <SerialFlash.h>
// GUItool: begin automatically generated code // GUItool: begin automatically generated code
AudioSynthSineCosine_F32 sine_cos1; //xy=76,532 AudioSynthSineCosine_F32 sine_cos1; //xy=76,532
AudioAnalyzeFFT256_IQ_F32 FFT256iq1; //xy=243,532 AudioAnalyzeFFT256_IQ_F32 FFT256iq1; //xy=243,532
AudioOutputI2S_F32 audioOutI2S1; //xy=246,591 AudioOutputI2S_F32 audioOutI2S1; //xy=246,591
AudioConnection_F32 patchCord1(sine_cos1, 0, FFT256iq1, 0); AudioConnection_F32 patchCord1(sine_cos1, 0, FFT256iq1, 0);
AudioConnection_F32 patchCord2(sine_cos1, 1, FFT256iq1, 1); AudioConnection_F32 patchCord2(sine_cos1, 1, FFT256iq1, 1);
//AudioControlSGTL5000 sgtl5000_1;
// GUItool: end automatically generated code // GUItool: end automatically generated code
void setup(void) { void setup(void) {
@ -24,27 +23,55 @@ void setup(void) {
Serial.begin(9600); Serial.begin(9600);
delay(1000); delay(1000);
AudioMemory_F32(20); AudioMemory_F32(20);
Serial.println("FFT256IQ Test"); Serial.println("FFT256IQ Test v2");
// sgtl5000_1.enable(); //start the audio board
// sgtl5000_1.inputSelect(AUDIO_INPUT_LINEIN); // or AUDIO_INPUT_MIC
sine_cos1.amplitude(0.5); // Initialize Waveform Generator sine_cos1.amplitude(1.0); // Initialize Waveform Generator
// bin spacing = 44117.648/256 = 172.335 172.3 * 4 = 689.335 Hz (T3.6) // bin spacing = 44117.648/256 = 172.335 172.3 * 4 = 689.335 Hz (T3.6)
// Half bin higher is 775.3 for testing windows // Half bin higher is 775.3 for testing windows
//sine_cos1.frequency(689.34f); //sine_cos1.frequency(689.34f);
sine_cos1.frequency(1723.35f);
// Pick T3.6 bin center
//sine_cos1.frequency(689.33);
// or pick T4.x bin center
//sine_cos1.frequency(689.0625f);
// or pick any old frequency
sine_cos1.frequency(7100.0);
// elect the output format
FFT256iq1.setOutputType(FFT_DBFS); FFT256iq1.setOutputType(FFT_DBFS);
// Select the wndow function
//FFT256iq1.windowFunction(AudioWindowNone);
//FFT256iq1.windowFunction(AudioWindowHanning256);
//FFT256iq1.windowFunction(AudioWindowKaiser256, 55.0f);
FFT256iq1.windowFunction(AudioWindowBlackmanHarris256);
// Uncomment to Serial print window function
//float* pw = FFT256iq1.getWindow(); // Print window
//for (int i=0; i<512; i++) Serial.println(pw[i], 4);
// xAxis, bit 0 left/right; bit 1 low to high; default 0X03
FFT256iq1.setXAxis(0X03);
FFT256iq1.windowFunction(AudioWindowBlackmanHarris256); FFT256iq1.windowFunction(AudioWindowBlackmanHarris256);
//float* pw = FFT256iq1.getWindow(); // Print window //float* pw = FFT256iq1.getWindow(); // Print window
//for (int i=0; i<256; i++) Serial.println(pw[i], 4); //for (int i=0; i<256; i++) Serial.println(pw[i], 4);
delay(1000); // Do power averaging (outputs appear less often, as well)
if( FFT256iq1.available() ) FFT256iq1.setNAverage(5); // nAverage >= 1
pPwr = FFT256iq1.getData();
for(int i=0; i<256; i++) delay(1000);
Serial.println(*(pPwr + i), 8 ); if( FFT256iq1.available() ) {
pPwr = FFT256iq1.getData();
for(int i=0; i<256; i++) {
Serial.print(i);
Serial.print(",");
Serial.println(*(pPwr + i), 8 );
}
Serial.print("\n\n");
}
} }
void loop(void) { void loop(void) {

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