ModemKit *ModemFMStereo::buildKit(long long sampleRate, int audioSampleRate) {
ModemKitFMStereo *kit = new ModemKitFMStereo;
kit->audioResampleRatio = double(audioSampleRate) / double(sampleRate);
kit->sampleRate = sampleRate;
kit->audioSampleRate = audioSampleRate;
float As = 60.0f; // stop-band attenuation [dB]
kit->audioResampler = msresamp_rrrf_create(kit->audioResampleRatio, As);
kit->stereoResampler = msresamp_rrrf_create(kit->audioResampleRatio, As);
// Stereo filters / shifters
double firStereoCutoff = 16000.0 / double(audioSampleRate);
// filter transition
float ft = 1000.0f / double(audioSampleRate);
// fractional timing offset
float mu = 0.0f;
if (firStereoCutoff < 0) {
firStereoCutoff = 0;
}
if (firStereoCutoff > 0.5) {
firStereoCutoff = 0.5;
}
unsigned int h_len = estimate_req_filter_len(ft, As);
float *h = new float[h_len];
liquid_firdes_kaiser(h_len, firStereoCutoff, As, mu, h);
kit->firStereoLeft = firfilt_rrrf_create(h, h_len);
kit->firStereoRight = firfilt_rrrf_create(h, h_len);
// stereo pilot filter
float bw = float(sampleRate);
if (bw < 100000.0) {
bw = 100000.0;
}
unsigned int order = 5; // filter order
float f0 = ((float) 19000 / bw);
float fc = ((float) 19500 / bw);
float Ap = 1.0f;
kit->iirStereoPilot = iirfilt_crcf_create_prototype(LIQUID_IIRDES_CHEBY2, LIQUID_IIRDES_BANDPASS, LIQUID_IIRDES_SOS, order, fc, f0, Ap, As);
kit->firStereoR2C = firhilbf_create(5, 60.0f);
kit->firStereoC2R = firhilbf_create(5, 60.0f);
kit->stereoPilot = nco_crcf_create(LIQUID_VCO);
nco_crcf_reset(kit->stereoPilot);
nco_crcf_pll_set_bandwidth(kit->stereoPilot, 0.25f);
return kit;
}
void DemodulatorPreThread::initialize() {
initialized = false;
iqResampleRatio = (double) (params.bandwidth) / (double) params.sampleRate;
audioResampleRatio = (double) (params.audioSampleRate) / (double) params.bandwidth;
float As = 120.0f; // stop-band attenuation [dB]
iqResampler = msresamp_crcf_create(iqResampleRatio, As);
audioResampler = msresamp_rrrf_create(audioResampleRatio, As);
stereoResampler = msresamp_rrrf_create(audioResampleRatio, As);
// Stereo filters / shifters
double firStereoCutoff = ((double) 16000 / (double) params.audioSampleRate);
float ft = ((double) 1000 / (double) params.audioSampleRate); // filter transition
float mu = 0.0f; // fractional timing offset
if (firStereoCutoff < 0) {
firStereoCutoff = 0;
}
if (firStereoCutoff > 0.5) {
firStereoCutoff = 0.5;
}
unsigned int h_len = estimate_req_filter_len(ft, As);
float *h = new float[h_len];
liquid_firdes_kaiser(h_len, firStereoCutoff, As, mu, h);
firStereoLeft = firfilt_rrrf_create(h, h_len);
firStereoRight = firfilt_rrrf_create(h, h_len);
// stereo pilot filter
float bw = params.bandwidth;
if (bw < 100000.0) {
bw = 100000.0;
}
unsigned int order = 5; // filter order
float f0 = ((double) 19000 / bw);
float fc = ((double) 19500 / bw);
float Ap = 1.0f;
As = 60.0f;
iirStereoPilot = iirfilt_crcf_create_prototype(LIQUID_IIRDES_CHEBY2, LIQUID_IIRDES_BANDPASS, LIQUID_IIRDES_SOS, order, fc, f0, Ap, As);
initialized = true;
lastParams = params;
}
// create gmskdem object
// _k : samples/symbol
// _m : filter delay (symbols)
// _BT : excess bandwidth factor
gmskdem gmskdem_create(unsigned int _k,
unsigned int _m,
float _BT)
{
if (_k < 2) {
fprintf(stderr,"error: gmskdem_create(), samples/symbol must be at least 2\n");
exit(1);
} else if (_m < 1) {
fprintf(stderr,"error: gmskdem_create(), symbol delay must be at least 1\n");
exit(1);
} else if (_BT <= 0.0f || _BT >= 1.0f) {
fprintf(stderr,"error: gmskdem_create(), bandwidth/time product must be in (0,1)\n");
exit(1);
}
// allocate memory for main object
gmskdem q = (gmskdem)malloc(sizeof(struct gmskdem_s));
// set properties
q->k = _k;
q->m = _m;
q->BT = _BT;
// allocate memory for filter taps
q->h_len = 2*(q->k)*(q->m)+1;
q->h = (float*) malloc(q->h_len * sizeof(float));
// compute filter coefficients
liquid_firdes_gmskrx(q->k, q->m, q->BT, 0.0f, q->h);
#if GMSKDEM_USE_EQUALIZER
// receiver matched filter/equalizer
q->eq = eqlms_rrrf_create_rnyquist(LIQUID_RNYQUIST_GMSKRX,
q->k,
q->m,
q->BT,
0.0f);
eqlms_rrrf_set_bw(q->eq, 0.01f);
q->k_inv = 1.0f / (float)(q->k);
#else
// create filter object
q->filter = firfilt_rrrf_create(q->h, q->h_len);
#endif
// reset modem state
gmskdem_reset(q);
#if DEBUG_GMSKDEM
q->debug_mfout = windowf_create(DEBUG_BUFFER_LEN);
#endif
// return modem object
return q;
}
//
// AUTOTEST : fir group delay, n=3
//
void autotest_fir_groupdelay_n3()
{
// create coefficients array
float h[3] = {0.1, 0.2, 0.4};
float tol = 1e-3f;
unsigned int i;
// create testing vectors
float fc[4] = { 0.000,
0.125,
0.250,
0.375};
float g0[4] = { 1.42857142857143,
1.54756605839643,
2.15384615384615,
2.56861651421767};
// run tests
float g;
for (i=0; i<4; i++) {
g = fir_group_delay(h, 3, fc[i]);
CONTEND_DELTA( g, g0[i], tol );
}
// create filter
firfilt_rrrf filter = firfilt_rrrf_create(h,3);
// run tests again
for (i=0; i<4; i++) {
g = firfilt_rrrf_groupdelay(filter, fc[i]);
CONTEND_DELTA( g, g0[i], tol );
}
// destroy filter
firfilt_rrrf_destroy(filter);
}
int main() {
// options
unsigned int h_len=17; // filter length
float fc=0.2f; // filter cutoff
float As=30.0f; // stop-band attenuation [dB]
float mu=0.0f; // timing offset
unsigned int n=64; // number of random input samples
// derived values
unsigned int num_samples = n + h_len;
// arrays
float x[num_samples]; // filter input
float y[num_samples]; // filter output
unsigned int i;
float h[h_len];
liquid_firdes_kaiser(h_len,fc,As,mu,h);
firfilt_rrrf f = firfilt_rrrf_create(h,h_len);
firfilt_rrrf_print(f);
for (i=0; i<num_samples; i++) {
// generate noise
x[i] = (i<n) ? randnf()/sqrtf(n/2) : 0.0f;
firfilt_rrrf_push(f, x[i]);
firfilt_rrrf_execute(f, &y[i]);
printf("x[%4u] = %12.8f, y[%4u] = %12.8f;\n", i, x[i], i, y[i]);
}
// destroy filter object
firfilt_rrrf_destroy(f);
//
// export results
//
FILE*fid = fopen(OUTPUT_FILENAME,"w");
fprintf(fid,"%% firfilt_rrrf_example.m: auto-generated file\n\n");
fprintf(fid,"clear all;\nclose all;\n\n");
fprintf(fid,"h_len=%u;\nn=%u;\n", h_len, n);
for (i=0; i<h_len; i++)
fprintf(fid,"h(%4u) = %12.4e;\n", i+1, h[i]);
for (i=0; i<num_samples; i++)
fprintf(fid,"x(%4u) = %12.4e; y(%4u) = %12.4e;\n", i+1, x[i], i+1, y[i]);
fprintf(fid,"nfft=512;\n");
fprintf(fid,"H=20*log10(abs(fftshift(fft(h,nfft))));\n");
fprintf(fid,"X=20*log10(abs(fftshift(fft(x,nfft))));\n");
fprintf(fid,"Y=20*log10(abs(fftshift(fft(y,nfft))));\n");
fprintf(fid,"f=[0:(nfft-1)]/nfft-0.5;\n");
fprintf(fid,"figure;\n");
fprintf(fid,"plot(f,X,'Color',[0.3 0.3 0.3],...\n");
fprintf(fid," f,Y,'LineWidth',2,...\n");
fprintf(fid," f,H,'-b','LineWidth',2);\n");
fprintf(fid,"axis([-0.5 0.5 -80 40]);\n");
fprintf(fid,"grid on;\nxlabel('normalized frequency');\nylabel('PSD [dB]');\n");
fprintf(fid,"legend('noise','filtered noise','filter prototype',1);");
fclose(fid);
printf("results written to %s\n", OUTPUT_FILENAME);
printf("done.\n");
return 0;
}
int main(int argc, char*argv[])
{
// options
unsigned int h_len=19; // filter length
unsigned int p=5; // polynomial order
float fc=0.45f; // filter cutoff
float As=60.0f; // stop-band attenuation [dB]
float mu=0.1f; // fractional sample delay
unsigned int num_samples=60; // number of samples to evaluate
int verbose = 0; // verbose output?
int dopt;
while ((dopt = getopt(argc,argv,"hvt:")) != EOF) {
switch (dopt) {
case 'h': usage(); return 0;
case 'v': verbose = 1; break;
case 't': mu = atof(optarg); break;
default:
exit(1);
}
}
// data arrays
float x[num_samples]; // input data array
float y[num_samples]; // output data array
// create and initialize Farrow filter object
firfarrow_rrrf f = firfarrow_rrrf_create(h_len, p, fc, As);
firfarrow_rrrf_set_delay(f, mu);
unsigned int i;
// generate input (filtered noise)
float hx[21];
liquid_firdes_kaiser(15, 0.1, 60, 0, hx);
firfilt_rrrf fx = firfilt_rrrf_create(hx, 15);
for (i=0; i<num_samples; i++) {
firfilt_rrrf_push(fx, i < 40 ? randnf() : 0.0f);
firfilt_rrrf_execute(fx, &x[i]);
}
firfilt_rrrf_destroy(fx);
// push input through filter
for (i=0; i<num_samples; i++) {
firfarrow_rrrf_push(f, x[i]);
firfarrow_rrrf_execute(f, &y[i]);
}
// destroy Farrow filter object
firfarrow_rrrf_destroy(f);
FILE*fid = fopen(OUTPUT_FILENAME,"w");
fprintf(fid,"%% %s : auto-generated file\n\n", OUTPUT_FILENAME);
fprintf(fid,"clear all;\nclose all;\n\n");
fprintf(fid,"h_len = %u;\n", h_len);
fprintf(fid,"mu = %f;\n", mu);
fprintf(fid,"num_samples = %u;\n", num_samples);
for (i=0; i<num_samples; i++) {
fprintf(fid,"x(%4u) = %12.4e; y(%4u) = %12.4e;\n", i+1, x[i], i+1, y[i]);
}
// plot the results
fprintf(fid,"\n\n");
fprintf(fid,"figure;\n");
fprintf(fid,"tx = 0:(num_samples-1); %% input time scale\n");
fprintf(fid,"ty = tx - (h_len-1)/2 + mu; %% output time scale\n");
fprintf(fid,"plot(tx, x,'-s','MarkerSize',3, ...\n");
fprintf(fid," ty, y,'-s','MarkerSize',3);\n");
fprintf(fid,"legend('input','output',0);\n");
fclose(fid);
printf("results written to %s\n", OUTPUT_FILENAME);
printf("done.\n");
return 0;
}
int main() {
// spectral periodogram options
unsigned int nfft = 1024; // spectral periodogram FFT size
unsigned int num_samples = 4000; // number of samples
float beta = 10.0f; // Kaiser-Bessel window parameter
float noise_floor = -60.0f; // noise floor [dB]
float alpha = 0.1f; // PSD estimate bandwidth
unsigned int i;
// derived values
float nstd = powf(10.0f, noise_floor/20.0f);
// create spectral periodogram
unsigned int window_size = nfft/2; // spgramf window size
spgramf q = spgramf_create_kaiser(nfft, window_size, beta);
// generate signal (filter with frequency offset)
unsigned int h_len = 91; // filter length
float fc = 0.07f; // filter cut-off frequency
float f0 = 0.20f; // filter center frequency
float As = 60.0f; // filter stop-band attenuation
float h[h_len]; // filter coefficients
liquid_firdes_kaiser(h_len, fc, As, 0, h);
// add frequency offset
for (i=0; i<h_len; i++)
h[i] *= cosf(2*M_PI*f0*i);
firfilt_rrrf filter = firfilt_rrrf_create(h, h_len);
firfilt_rrrf_set_scale(filter, 2.0f*fc);
for (i=0; i<num_samples; i++) {
// generate random sample
float x = randnf();
// filter
float y = 0;
firfilt_rrrf_push(filter, x);
firfilt_rrrf_execute(filter, &y);
// add noise
y += nstd * randnf();
// push resulting sample through periodogram
spgramf_accumulate_psd(q, &y, alpha, 1);
}
// compute power spectral density output
float psd[nfft];
spgramf_write_accumulation(q, psd);
// destroy objects
firfilt_rrrf_destroy(filter);
spgramf_destroy(q);
//
// export output file
//
FILE * fid = fopen(OUTPUT_FILENAME,"w");
fprintf(fid,"%% %s : auto-generated file\n", OUTPUT_FILENAME);
fprintf(fid,"clear all;\n");
fprintf(fid,"close all;\n\n");
fprintf(fid,"nfft = %u;\n", nfft);
fprintf(fid,"f = [0:(nfft-1)]/nfft - 0.5;\n");
fprintf(fid,"H = zeros(1,nfft);\n");
fprintf(fid,"noise_floor = %12.6f;\n", noise_floor);
for (i=0; i<nfft; i++)
fprintf(fid,"H(%6u) = %12.4e;\n", i+1, psd[i]);
fprintf(fid,"figure;\n");
fprintf(fid,"plot(f, H, '-', 'LineWidth',1.5);\n");
fprintf(fid,"xlabel('Normalized Frequency [f/F_s]');\n");
fprintf(fid,"ylabel('Power Spectral Density [dB]');\n");
fprintf(fid,"grid on;\n");
fprintf(fid,"ymin = 10*floor([noise_floor-20]/10);\n");
fprintf(fid,"ymax = 10*floor([noise_floor+80]/10);\n");
fprintf(fid,"axis([-0.5 0.5 ymin ymax]);\n");
fclose(fid);
printf("results written to %s.\n", OUTPUT_FILENAME);
printf("done.\n");
return 0;
}
void DemodulatorWorkerThread::threadMain() {
std::cout << "Demodulator worker thread started.." << std::endl;
while (!terminated) {
bool filterChanged = false;
DemodulatorWorkerThreadCommand filterCommand;
DemodulatorWorkerThreadCommand command;
bool done = false;
while (!done) {
commandQueue->pop(command);
switch (command.cmd) {
case DemodulatorWorkerThreadCommand::DEMOD_WORKER_THREAD_CMD_BUILD_FILTERS:
filterChanged = true;
filterCommand = command;
break;
default:
break;
}
done = commandQueue->empty();
}
if (filterChanged && !terminated) {
DemodulatorWorkerThreadResult result(DemodulatorWorkerThreadResult::DEMOD_WORKER_THREAD_RESULT_FILTERS);
float As = 60.0f; // stop-band attenuation [dB]
if (filterCommand.sampleRate && filterCommand.bandwidth) {
result.iqResampleRatio = (double) (filterCommand.bandwidth) / (double) filterCommand.sampleRate;
result.iqResampler = msresamp_crcf_create(result.iqResampleRatio, As);
}
if (filterCommand.bandwidth && filterCommand.audioSampleRate) {
result.audioResamplerRatio = (double) (filterCommand.audioSampleRate) / (double) filterCommand.bandwidth;
result.audioResampler = msresamp_rrrf_create(result.audioResamplerRatio, As);
result.stereoResampler = msresamp_rrrf_create(result.audioResamplerRatio, As);
result.audioSampleRate = filterCommand.audioSampleRate;
// Stereo filters / shifters
double firStereoCutoff = ((double) 16000 / (double) filterCommand.audioSampleRate);
float ft = ((double) 1000 / (double) filterCommand.audioSampleRate); // filter transition
float mu = 0.0f; // fractional timing offset
if (firStereoCutoff < 0) {
firStereoCutoff = 0;
}
if (firStereoCutoff > 0.5) {
firStereoCutoff = 0.5;
}
unsigned int h_len = estimate_req_filter_len(ft, As);
float *h = new float[h_len];
liquid_firdes_kaiser(h_len, firStereoCutoff, As, mu, h);
result.firStereoLeft = firfilt_rrrf_create(h, h_len);
result.firStereoRight = firfilt_rrrf_create(h, h_len);
float bw = filterCommand.bandwidth;
if (bw < 100000.0) {
bw = 100000.0;
}
// stereo pilot filter
unsigned int order = 5; // filter order
float f0 = ((double) 19000 / bw);
float fc = ((double) 19500 / bw);
float Ap = 1.0f;
As = 60.0f;
result.iirStereoPilot = iirfilt_crcf_create_prototype(LIQUID_IIRDES_CHEBY2, LIQUID_IIRDES_BANDPASS, LIQUID_IIRDES_SOS, order, fc, f0, Ap, As);
}
if (filterCommand.bandwidth) {
result.bandwidth = filterCommand.bandwidth;
}
if (filterCommand.sampleRate) {
result.sampleRate = filterCommand.sampleRate;
}
resultQueue->push(result);
}
}
std::cout << "Demodulator worker thread done." << std::endl;
}
