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Simplify/fix PLL, tweak parameters

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This commit is contained in:
Charles J. Cliffe 2015-06-05 20:58:10 -04:00
parent 0ccd5b4156
commit 234ac5bd15
3 changed files with 36 additions and 49 deletions
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6
src/demod/DemodulatorPreThread.cpp
View File

@ -37,8 +37,8 @@ void DemodulatorPreThread::initialize() {
stereoResampler = msresamp_rrrf_create(audioResampleRatio, As);
// Stereo filters / shifters
double firStereoCutoff = 0.5 * ((double) 36000 / (double) params.audioSampleRate); // filter cutoff frequency
float ft = 0.05f; // filter transition
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) {
@ -59,7 +59,7 @@ void DemodulatorPreThread::initialize() {
// stereo pilot filter
unsigned int order = 5; // filter order
float f0 = ((double) 19000 / (double) params.bandwidth);
float fc = f0 + ((double) 3000 / (double) params.bandwidth);
float fc = ((double) 19500 / (double) params.bandwidth);
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);

69
src/demod/DemodulatorThread.cpp
View File

@ -47,18 +47,14 @@ void DemodulatorThread::threadMain() {
firfilt_rrrf firStereoRight = NULL;
iirfilt_crcf iirStereoPilot = NULL;
liquid_float_complex u, v, w, x, y, z[2];
float rz[2];
liquid_float_complex u, v, w, x, y;
firhilbf firStereoR2C = firhilbf_create(5, 60.0f);
firhilbf firStereoC2R = firhilbf_create(5, 60.0f);
nco_crcf stereoShifter = nco_crcf_create(LIQUID_NCO);
double stereoShiftFrequency = 0;
nco_crcf stereoPilot = nco_crcf_create(LIQUID_NCO);
nco_crcf_pll_set_bandwidth(stereoPilot, 0.05f);
nco_crcf stereoPilot = nco_crcf_create(LIQUID_VCO);
nco_crcf_reset(stereoPilot);
nco_crcf_pll_set_bandwidth(stereoPilot, 0.25f);
// half band filter used for side-band elimination
resamp2_cccf ssbFilt = resamp2_cccf_create(12,-0.25f,60.0f);
@ -121,7 +117,6 @@ void DemodulatorThread::threadMain() {
ampmodem_reset(demodAM);
}
freqdem_reset(demodFM);
nco_crcf_reset(stereoPilot);
}
if (firStereoLeft != inp->firStereoLeft) {
@ -236,38 +231,38 @@ void DemodulatorThread::threadMain() {
demodStereoData.resize(bufSize);
}
double freq = (2.0 * M_PI) * ((double) 38000) / ((double) inp->sampleRate);
if (stereoShiftFrequency != freq) {
nco_crcf_set_frequency(stereoShifter, freq);
stereoShiftFrequency = freq;
}
float phase_error = 0;
for (int i = 0; i < bufSize; i++) {
firhilbf_r2c_execute(firStereoR2C, demodOutputData[i], &x);
nco_crcf_mix_down(stereoShifter, x, &y);
nco_crcf_step(stereoShifter);
nco_crcf_step(stereoPilot);
for (int i = 0; i < bufSize; i++) {
// real -> complex
firhilbf_r2c_execute(firStereoR2C, demodOutputData[i], &x);
// 19khz pilot band-pass
iirfilt_crcf_execute(iirStereoPilot, x, &v);
nco_crcf_cexpf(stereoPilot, &w);
w.imag = -w.imag; // conjf(w)
u.real = v.real * w.real - v.imag * (-w.imag);
u.imag = v.real * (-w.imag) + v.imag * w.real;
// multiply u = v * conjf(w)
u.real = v.real * w.real - v.imag * w.imag;
u.imag = v.real * w.imag + v.imag * w.real;
// cargf(u)
phase_error = atan2f(u.imag,u.real);
// step pll
nco_crcf_pll_step(stereoPilot, phase_error);
firhilbf_c2r_execute(firStereoC2R, y, &demodStereoData[i]);
nco_crcf_step(stereoPilot);
// 38khz down-mix
nco_crcf_mix_down(stereoPilot, x, &y);
nco_crcf_mix_down(stereoPilot, y, &x);
// complex -> real
firhilbf_c2r_execute(firStereoC2R, x, &demodStereoData[i]);
}
// if (fabs(fabs((((nco_crcf_get_frequency(stereoPilot) / (2.0 * M_PI)) * inp->sampleRate)))-19000) > 2000) {
// nco_crcf_reset(stereoPilot);
// nco_crcf_set_frequency(stereoPilot, freq/2);
// }
//
nco_crcf_set_frequency(stereoShifter, nco_crcf_get_frequency(stereoPilot)*2);
nco_crcf_set_phase(stereoShifter, nco_crcf_get_phase(stereoPilot));
// std::cout << "[PLL] phase error: " << phase_error;
// std::cout << " freq:" << (((nco_crcf_get_frequency(stereoPilot) / (2.0 * M_PI)) * inp->sampleRate)) << std::endl;
@ -316,16 +311,11 @@ void DemodulatorThread::threadMain() {
for (int i = 0; i < numAudioWritten; i++) {
float l, r;
firfilt_rrrf_push(firStereoLeft, (resampledOutputData[i] - (resampledStereoData[i])));
firfilt_rrrf_push(firStereoLeft, 0.568 * (resampledOutputData[i] - (resampledStereoData[i])));
firfilt_rrrf_execute(firStereoLeft, &l);
firfilt_rrrf_push(firStereoRight, (resampledOutputData[i] + (resampledStereoData[i])));
firfilt_rrrf_push(firStereoRight, 0.568 * (resampledOutputData[i] + (resampledStereoData[i])));
firfilt_rrrf_execute(firStereoRight, &r);
// firfilt_rrrf_push(firStereoLeft, (resampledStereoData[i]));
// firfilt_rrrf_execute(firStereoLeft, &l);
//
// firfilt_rrrf_push(firStereoRight, (resampledStereoData[i]));
// firfilt_rrrf_execute(firStereoRight, &r);
ati->data[i * 2] = l;
ati->data[i * 2 + 1] = r;
@ -354,8 +344,6 @@ void DemodulatorThread::threadMain() {
int num_vis = DEMOD_VIS_SIZE;
if (stereo) {
// ati_vis->channels = 1;
// ati_vis->data.assign(demodStereoData.begin(), demodStereoData.begin() + num_vis);
ati_vis->channels = 2;
int stereoSize = ati->data.size();
if (stereoSize > DEMOD_VIS_SIZE) {
@ -460,7 +448,6 @@ void DemodulatorThread::threadMain() {
agc_crcf_destroy(iqAutoGain);
firhilbf_destroy(firStereoR2C);
firhilbf_destroy(firStereoC2R);
nco_crcf_destroy(stereoShifter);
nco_crcf_destroy(stereoPilot);
resamp2_cccf_destroy(ssbFilt);

10
src/demod/DemodulatorWorkerThread.cpp
View File

@ -51,8 +51,8 @@ void DemodulatorWorkerThread::threadMain() {
result.audioSampleRate = filterCommand.audioSampleRate;
// Stereo filters / shifters
double firStereoCutoff = 0.5 * ((double) 36000 / (double) filterCommand.audioSampleRate); // filter cutoff frequency
float ft = 0.05f; // filter transition
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) {
@ -70,10 +70,10 @@ void DemodulatorWorkerThread::threadMain() {
result.firStereoLeft = firfilt_rrrf_create(h, h_len);
result.firStereoRight = firfilt_rrrf_create(h, h_len);
unsigned int order = 5;
// stereo pilot filter
unsigned int order = 5; // filter order
float f0 = ((double) 19000 / (double) filterCommand.bandwidth);
float fc = f0 + ((double) 3000 / (double) filterCommand.bandwidth);
float fc = ((double) 19500 / (double) filterCommand.bandwidth);
float Ap = 1.0f;
As = 60.0f;