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CubicSDR
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Bonus SSB optimize/tweak

This commit is contained in:
Charles J. Cliffe 2016-02-02 20:41:12 -05:00
parent cc189cc274
commit 090d751482
2 changed files with 8 additions and 10 deletions
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9
src/modules/modem/analog/ModemLSB.cpp
View File

@ -2,12 +2,12 @@
ModemLSB::ModemLSB() : ModemAnalog() {
// half band filter used for side-band elimination
demodAM_LSB = ampmodem_create(0.5, 0.0, LIQUID_AMPMODEM_LSB, 1);
demodAM_LSB = ampmodem_create(0.25, 0.25, LIQUID_AMPMODEM_LSB, 1);
// options
float fc = 0.25f; // filter cutoff frequency
float ft = 0.05f; // filter transition
float As = 90.0f; // stop-band attenuation [dB]
float mu = 0.0f; // fractional timing offset
float mu = 0.5f; // fractional timing offset
// estimate required filter length and generate filter
unsigned int h_len = estimate_req_filter_len(ft,As);
@ -57,14 +57,13 @@ void ModemLSB::demodulate(ModemKit *kit, ModemIQData *input, AudioThreadInput *a
return;
}
liquid_float_complex x, y;
liquid_float_complex x;
for (int i = 0; i < bufSize; i++) { // Reject upper band
nco_crcf_step(ssbShift);
nco_crcf_mix_up(ssbShift, input->data[i], &x);
firfilt_crcf_push(ssbFilt, x);
firfilt_crcf_execute(ssbFilt, &x);
nco_crcf_mix_down(ssbShift, x, &y);
ampmodem_demodulate(demodAM_LSB, y, &demodOutputData[i]);
ampmodem_demodulate(demodAM_LSB, x, &demodOutputData[i]);
}
buildAudioOutput(akit, audioOut, true);

9
src/modules/modem/analog/ModemUSB.cpp
View File

@ -2,12 +2,12 @@
ModemUSB::ModemUSB() : ModemAnalog() {
// half band filter used for side-band elimination
demodAM_USB = ampmodem_create(0.5, 0.0, LIQUID_AMPMODEM_USB, 1);
demodAM_USB = ampmodem_create(0.25, -0.25, LIQUID_AMPMODEM_USB, 1);
// options
float fc = 0.25f; // filter cutoff frequency
float ft = 0.05f; // filter transition
float As = 90.0f; // stop-band attenuation [dB]
float mu = 0.0f; // fractional timing offset
float mu = 0.5f; // fractional timing offset
// estimate required filter length and generate filter
unsigned int h_len = estimate_req_filter_len(ft,As);
@ -57,14 +57,13 @@ void ModemUSB::demodulate(ModemKit *kit, ModemIQData *input, AudioThreadInput *a
return;
}
liquid_float_complex x, y;
liquid_float_complex x;
for (int i = 0; i < bufSize; i++) { // Reject lower band
nco_crcf_step(ssbShift);
nco_crcf_mix_down(ssbShift, input->data[i], &x);
firfilt_crcf_push(ssbFilt, x);
firfilt_crcf_execute(ssbFilt, &x);
nco_crcf_mix_up(ssbShift, x, &y);
ampmodem_demodulate(demodAM_USB, y, &demodOutputData[i]);
ampmodem_demodulate(demodAM_USB, x, &demodOutputData[i]);
}
buildAudioOutput(akit, audioOut, true);