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filtering / fm demod experiments

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This commit is contained in:
Charles J. Cliffe 2014-11-07 01:47:57 -05:00
parent 42034717c5
commit 44e7744855
3 changed files with 100 additions and 56 deletions
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7
src/Demodulate.h
View File

@ -42,6 +42,13 @@ struct controller_state {
int wb_mode;
};
/* define our own complex math ops
because ARMv5 has no hardware float */
void multiply(int ar, int aj, int br, int bj, int *cr, int *cj);
int polar_discriminant(int ar, int aj, int br, int bj);
int fast_atan2(int y, int x);
int polar_disc_fast(int ar, int aj, int br, int bj);
class Demodulate {
public:

146
src/PrimaryGLContext.cpp
View File

@ -86,7 +86,7 @@ void PrimaryGLContext::Plot(std::vector<float> &points, std::vector<float> &poin
if (points2.size()) {
glPushMatrix();
glTranslatef(-1.0f, 0.5f, 0.0f);
glScalef(20.0f, 0.5f, 1.0f);
glScalef(2.0f, 0.5f, 1.0f);
glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(2, GL_FLOAT, 0, &points2[0]);
glDrawArrays(GL_LINE_STRIP, 0, points2.size() / 2);
@ -152,34 +152,45 @@ TestGLCanvas::TestGLCanvas(wxWindow *parent, int *attribList) :
if (alGetError() != AL_NO_ERROR) {
std::cout << "Error starting :(\n";
}
/*
// define filter length, type, number of bands
unsigned int n = 55;
liquid_firdespm_btype btype = LIQUID_FIRDESPM_BANDPASS;
unsigned int num_bands = 3;
// define filter length, type, number of bands
unsigned int n = 55;
liquid_firdespm_btype btype = LIQUID_FIRDESPM_BANDPASS;
unsigned int num_bands = 3;
// band edge description [size: num_bands x 2]
float bands[6] = { 0.0f, 0.14f, 0.15f, 0.35f, 0.36f, 0.5f };
// band edge description [size: num_bands x 2]
float bands[6] = { 0.0f, 0.14f, 0.15f, 0.35f, 0.36f, 0.5f };
// desired response [size: num_bands x 1]
float des[3] = { 1.0f, 0.0f, 1.0f };
// desired response [size: num_bands x 1]
float des[3] = { 1.0f, 0.0f, 1.0f };
// relative weights [size: num_bands x 1]
float weights[3] = { 1.0f, 1.0f, 1.0f };
// relative weights [size: num_bands x 1]
float weights[3] = { 1.0f, 1.0f, 1.0f };
// in-band weighting functions [size: num_bands x 1]
liquid_firdespm_wtype wtype[3] = { LIQUID_FIRDESPM_FLATWEIGHT, LIQUID_FIRDESPM_EXPWEIGHT, LIQUID_FIRDESPM_FLATWEIGHT };
// in-band weighting functions [size: num_bands x 1]
liquid_firdespm_wtype wtype[3] = { LIQUID_FIRDESPM_FLATWEIGHT, LIQUID_FIRDESPM_EXPWEIGHT, LIQUID_FIRDESPM_FLATWEIGHT };
// allocate memory for array and design filter
float h[n];
firdespm_run(n, num_bands, bands, des, weights, wtype, btype, h);
*/
// allocate memory for array and design filter
float h[n];
firdespm_run(n, num_bands, bands, des, weights, wtype, btype, h);
float fc = 0.5f * (170000 / SRATE); // filter cutoff frequency
float ft = 0.05f; // filter transition
float As = 60.0f; // stop-band attenuation [dB]
float mu = 0.0f; // fractional timing offset
fir_filter = firfilt_crcf_create(h, n);
unsigned int m=5; // filter semi-length
float slsl=60.0f; // filter sidelobe suppression level
fir_hil = firhilbf_create(m,slsl);
// estimate required filter length and generate filter
unsigned int h_len = estimate_req_filter_len(ft, As);
float h[h_len];
liquid_firdes_kaiser(h_len, fc, As, mu, h);
fir_filter = firfilt_crcf_create(h, h_len);
unsigned int m = 5; // filter semi-length
float slsl = 60.0f; // filter sidelobe suppression level
fir_hil = firhilbf_create(m, slsl);
}
TestGLCanvas::~TestGLCanvas() {
@ -323,11 +334,11 @@ void TestGLCanvas::setData(std::vector<signed char> *data) {
}
// for (int i = 0, iMax = FFT_SIZE; i < iMax; i++) {
// if (i>FFT_SIZE/4 && i < FFT_SIZE-FFT_SIZE/4) {
// out[0][i][0] = 0;
// out[0][i][1] = 0;
// }
// }
// if (i>FFT_SIZE/4 && i < FFT_SIZE-FFT_SIZE/4) {
// out[0][i][0] = 0;
// out[0][i][1] = 0;
// }
// }
for (int j = 0; j < 2; j++) {
for (int i = 0, iMax = FFT_SIZE / 2; i < iMax; i++) {
@ -339,8 +350,8 @@ void TestGLCanvas::setData(std::vector<signed char> *data) {
double y = out[0][FFT_SIZE / 2 + i][1];
double z = sqrt(x * x + y * y);
fft_result[i] = z;
fft_result[FFT_SIZE/2 + i] = c;
fft_result[i] = log10(z);
fft_result[FFT_SIZE / 2 + i] = log10(c);
}
}
@ -358,45 +369,68 @@ void TestGLCanvas::setData(std::vector<signed char> *data) {
fft_ceil_ma = fft_ceil_ma + (fft_ceil - fft_ceil_ma) * 0.05;
fft_ceil_maa = fft_ceil_maa + (fft_ceil - fft_ceil_maa) * 0.05;
fftw_execute(plan[1]);
for (int i = 0, iMax = FFT_SIZE; i < iMax; i++) {
spectrum_points[i * 2 + 1] = fft_result_maa[i] / fft_ceil_maa;
spectrum_points[i * 2] = ((double) i / (double) iMax);
}
if (waveform_points.size() < BUF_SIZE * 2) {
waveform_points.resize(BUF_SIZE * 2);
}
float waveform_ceil = 0;
for (int i = 0, iMax = FFT_SIZE; i < iMax; i++) {
float a = out[1][i][0];
float b = out[1][i][1];
float c = sqrt(a*a+b*b);
float v = fabs(c);
if (v > waveform_ceil) {
waveform_ceil = v;
}
std::vector<float> output_buffer;
output_buffer.resize(BUF_SIZE / 2);
// for (int i = 0, iMax = BUF_SIZE / 2; i < iMax; i++) {
// liquid_float_complex x;
// x.real = in[i][0];
// x.imag = in[i][1];
// float y[2];
//
// firhilbf_interp_execute(fir_hil, x, y);
// output_buffer[i] = y[1];
//
// if (waveform_ceil < y[1]) {
// waveform_ceil = y[1];
// }
// }
if (waveform_points.size() < BUF_SIZE) {
waveform_points.resize(BUF_SIZE);
}
for (int i = 0, iMax = BUF_SIZE/2; i < iMax; i++) {
liquid_float_complex x;
x.real = in[i][0];
x.imag = in[i][1];
float y[2];
firhilbf_interp_execute(fir_hil, x, y);
waveform_points[i * 4 + 1] = y[0];
waveform_points[i * 4] = ((double) i / (double) iMax);
waveform_points[i * 4 + 3] = y[1];
waveform_points[i * 4 + 2] = ((double) i / (double) iMax);
int i, pcm = 0;
int16_t pr = pre_r;
int16_t pj = pre_j;
for (i = 0; i < BUF_SIZE / 2; i++) {
// liquid_float_complex x;
// x.real = in[i][0];
// x.imag = in[i][1];
// float y[2];
//
// firhilbf_interp_execute(fir_hil, x, y);
// y[0] *= 10000.0;
// y[1] *= 1000.0;
pcm = polar_disc_fast((int)(in[i][0]*60.0), (int)(in[i][1]*60.0), pr, pj);
pr = (int)(in[i][0]*10.0);
pj = (int)(in[i][1]*10.0);
output_buffer[i] = (float)pcm/60.0;
if (waveform_ceil < output_buffer[i]) {
waveform_ceil = output_buffer[i];
}
}
pre_r = pr;
pre_j = pj;
for (int i = 0, iMax = BUF_SIZE / 2; i < iMax; i++) {
waveform_points[i * 2 + 1] = output_buffer[i] / waveform_ceil;
waveform_points[i * 2] = ((double) i / (double) iMax);
}
}
}

3
src/PrimaryGLContext.h
View File

@ -59,6 +59,9 @@ private:
firhilbf fir_hil;
int16_t pre_r;
int16_t pre_j;
float fft_ceil_ma, fft_ceil_maa;
std::vector<float> fft_result;