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Simplify SSB demod with resamp2 half-band filter

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This commit is contained in:
Charles J. Cliffe 2015-02-19 23:51:24 -05:00
parent 14881acdc9
commit 4e26c2a38a
1 changed files with 9 additions and 40 deletions
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49
src/demod/DemodulatorThread.cpp
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@ -73,16 +73,8 @@ void DemodulatorThread::threadMain() {
nco_crcf stereoShifter = nco_crcf_create(LIQUID_NCO);
double stereoShiftFrequency = 0;
// SSB Half-band filter
nco_crcf ssbShifterUp = nco_crcf_create(LIQUID_NCO);
nco_crcf_set_frequency(ssbShifterUp, (2.0 * M_PI) * 0.25);
nco_crcf ssbShifterDown = nco_crcf_create(LIQUID_NCO);
nco_crcf_set_frequency(ssbShifterDown, (2.0 * M_PI) * 0.25);
// half band interp / decimate used for side-band elimination
resamp2_crcf ssbInterp = resamp2_crcf_create(7, 0.0f, -120.0f);
resamp2_crcf ssbDecim = resamp2_crcf_create(7, 0.0f, -120.0f);
// half band filter used for side-band elimination
resamp2_cccf ssbFilt = resamp2_cccf_create(12,-0.25f,60.0f);
// Automatic IQ gain
iqAutoGain = agc_crcf_create();
@ -175,37 +167,15 @@ void DemodulatorThread::threadMain() {
float p;
switch (demodulatorType.load()) {
case DEMOD_TYPE_LSB:
for (int i = 0; i < bufSize / 2; i++) { // Reject upper band
nco_crcf_mix_up(ssbShifterUp, inp->data[i * 2], &z[0]);
nco_crcf_step(ssbShifterUp);
nco_crcf_mix_up(ssbShifterUp, inp->data[i * 2 + 1], &z[1]);
nco_crcf_step(ssbShifterUp);
resamp2_crcf_decim_execute(ssbDecim, z, &x);
resamp2_crcf_interp_execute(ssbInterp, x, z);
nco_crcf_mix_down(ssbShifterDown, z[0], &x);
nco_crcf_step(ssbShifterDown);
nco_crcf_mix_down(ssbShifterDown, z[1], &y);
nco_crcf_step(ssbShifterDown);
ampmodem_demodulate(demodAM, x, &demodOutputData[i * 2]);
ampmodem_demodulate(demodAM, y, &demodOutputData[i * 2 + 1]);
for (int i = 0; i < bufSize; i++) { // Reject upper band
resamp2_cccf_filter_execute(ssbFilt,inp->data[i],&x,&y);
ampmodem_demodulate(demodAM, x, &demodOutputData[i]);
}
break;
case DEMOD_TYPE_USB:
for (int i = 0; i < bufSize / 2; i++) { // Reject lower band
nco_crcf_mix_down(ssbShifterDown, inp->data[i * 2], &z[0]);
nco_crcf_step(ssbShifterDown);
nco_crcf_mix_down(ssbShifterDown, inp->data[i * 2 + 1], &z[1]);
nco_crcf_step(ssbShifterDown);
resamp2_crcf_decim_execute(ssbDecim, z, &x);
resamp2_crcf_interp_execute(ssbInterp, x, z);
nco_crcf_mix_up(ssbShifterUp, z[0], &x);
nco_crcf_step(ssbShifterUp);
nco_crcf_mix_up(ssbShifterUp, z[1], &y);
nco_crcf_step(ssbShifterUp);
ampmodem_demodulate(demodAM, x, &demodOutputData[i * 2]);
ampmodem_demodulate(demodAM, y, &demodOutputData[i * 2 + 1]);
for (int i = 0; i < bufSize; i++) { // Reject lower band
resamp2_cccf_filter_execute(ssbFilt,inp->data[i],&x,&y);
ampmodem_demodulate(demodAM, y, &demodOutputData[i]);
}
break;
case DEMOD_TYPE_AM:
@ -441,8 +411,7 @@ void DemodulatorThread::threadMain() {
firhilbf_destroy(firStereoR2C);
firhilbf_destroy(firStereoC2R);
nco_crcf_destroy(stereoShifter);
nco_crcf_destroy(ssbShifterUp);
nco_crcf_destroy(ssbShifterDown);
resamp2_cccf_destroy(ssbFilt);
while (!outputBuffers.empty()) {
AudioThreadInput *audioDataDel = outputBuffers.front();