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;
}
int main() {
// options
unsigned int order=4; // filter order
float fc=0.1f; // cutoff frequency
float f0=0.25f; // center frequency (bandpass|bandstop)
float Ap=1.0f; // pass-band ripple [dB]
float As=40.0f; // stop-band attenuation [dB]
liquid_iirdes_filtertype ftype = LIQUID_IIRDES_ELLIP;
liquid_iirdes_bandtype btype = LIQUID_IIRDES_BANDPASS;
liquid_iirdes_format format = LIQUID_IIRDES_SOS;
// CREATE filter object (and print to stdout)
iirfilt_crcf myfilter;
myfilter = iirfilt_crcf_create_prototype(ftype,
btype,
format,
order,
fc, f0,
Ap, As);
iirfilt_crcf_print(myfilter);
// allocate memory for data arrays
unsigned int n=128; // number of samples
float complex x[n]; // input samples array
float complex y[n]; // output samples array
// run filter
unsigned int i;
for (i=0; i<n; i++) {
// initialize input
x[i] = randnf() + _Complex_I*randnf();
// EXECUTE filter (repeat as many times as desired)
iirfilt_crcf_execute(myfilter, x[i], &y[i]);
}
// DESTROY filter object
iirfilt_crcf_destroy(myfilter);
}
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;
}
