diff --git a/plugins/channel/usb/usbdemod.cpp b/plugins/channel/usb/usbdemod.cpp index d34b04680..e62e342ed 100644 --- a/plugins/channel/usb/usbdemod.cpp +++ b/plugins/channel/usb/usbdemod.cpp @@ -32,19 +32,19 @@ USBDemod::USBDemod(AudioFifo* audioFifo, SampleSink* sampleSink) : m_volume = 2.0; m_sampleRate = 96000; m_frequency = 0; - m_nco.setFreq(m_frequency, m_sampleRate); - m_interpolator.create(16, m_sampleRate, 5000); m_sampleDistanceRemain = (Real)m_sampleRate / 48000.0; - m_lowpass.create(21, 48000, 5000); - m_audioBuffer.resize(512); m_audioBufferFill = 0; m_undersampleCount = 0; + + USBFilter = new fftfilt(0.01, m_Bandwidth / 48000.0, usbFftLen); + // if (!USBFilter) segfault; } USBDemod::~USBDemod() { + if (USBFilter) delete USBFilter; } void USBDemod::configure(MessageQueue* messageQueue, Real Bandwidth, Real volume) @@ -55,18 +55,23 @@ void USBDemod::configure(MessageQueue* messageQueue, Real Bandwidth, Real volume void USBDemod::feed(SampleVector::const_iterator begin, SampleVector::const_iterator end, bool positiveOnly) { - Complex ci; + Real a, b; + Complex c; + int n_out; + cmplx *sideband; bool consumed; for(SampleVector::const_iterator it = begin; it < end; ++it) { - Complex c(it->real() / 32768.0, it->imag() / 32768.0); - c *= m_nco.nextIQ(); + a = it->real(); + b = it->imag(); + it++; // TODO: Assumes 96kHz; Expect breakage. + a += it->real(); + b += it->imag(); + c = Complex(a / 32678.0, b / 32768.0); - consumed = false; - // could squelch audio if RTL_SDR samplerate is not being fully decimated. - if(m_interpolator.interpolate(&m_sampleDistanceRemain, c, &consumed, &ci)) { - Real demod = ci.imag() + ci.real(); - demod = 32768.0 * m_lowpass.filter(demod * 0.7); + n_out = USBFilter->run(c, &sideband); + for (int i = 0; i < n_out; i++) { + Real demod = (sideband[i].real() + sideband[i].imag()) * 0.7 * 32768.0; // Downsample by 4x for audio display if (!(m_undersampleCount++ & 3)) @@ -80,7 +85,7 @@ void USBDemod::feed(SampleVector::const_iterator begin, SampleVector::const_iter uint res = m_audioFifo->write((const quint8*)&m_audioBuffer[0], m_audioBufferFill, 1); m_audioBufferFill = 0; } - m_sampleDistanceRemain += (Real)m_sampleRate / 48000.0; + m_sampleDistanceRemain += 2; // 96k in / 48k out } } if(m_audioFifo->write((const quint8*)&m_audioBuffer[0], m_audioBufferFill, 0) != m_audioBufferFill) @@ -104,18 +109,14 @@ bool USBDemod::handleMessage(Message* cmd) { if(DSPSignalNotification::match(cmd)) { DSPSignalNotification* signal = (DSPSignalNotification*)cmd; - qDebug("%d samples/sec, %lld Hz offset", signal->getSampleRate(), signal->getFrequencyOffset()); m_sampleRate = signal->getSampleRate(); - m_nco.setFreq(-signal->getFrequencyOffset(), m_sampleRate); - m_interpolator.create(16, m_sampleRate, m_Bandwidth); - m_sampleDistanceRemain = m_sampleRate / 48000.0; + m_sampleDistanceRemain = 0.0; cmd->completed(); return true; } else if(MsgConfigureUSBDemod::match(cmd)) { MsgConfigureUSBDemod* cfg = (MsgConfigureUSBDemod*)cmd; m_Bandwidth = cfg->getBandwidth(); - m_interpolator.create(16, m_sampleRate, m_Bandwidth); - m_lowpass.create(21, 48000, cfg->getBandwidth()); + USBFilter->create_filter(0.01, m_Bandwidth / 48000.0); m_volume = cfg->getVolume(); m_volume *= m_volume * 0.1; cmd->completed(); diff --git a/plugins/channel/usb/usbdemod.h b/plugins/channel/usb/usbdemod.h index 26bc5efab..c9d605868 100644 --- a/plugins/channel/usb/usbdemod.h +++ b/plugins/channel/usb/usbdemod.h @@ -23,9 +23,12 @@ #include "dsp/nco.h" #include "dsp/interpolator.h" #include "dsp/lowpass.h" +#include "dsp/fftfilt.h" #include "audio/audiofifo.h" #include "util/message.h" +#define usbFftLen 1024 + class AudioFifo; class USBDemod : public SampleSink { @@ -84,6 +87,7 @@ private: AudioVector m_audioBuffer; uint m_audioBufferFill; AudioFifo* m_audioFifo; + fftfilt* USBFilter; SampleSink* m_sampleSink; SampleVector m_sampleBuffer; diff --git a/sdrbase/dsp/fftfilt.cxx b/sdrbase/dsp/fftfilt.cxx index 2f7437548..1de6a2aae 100644 --- a/sdrbase/dsp/fftfilt.cxx +++ b/sdrbase/dsp/fftfilt.cxx @@ -155,8 +155,11 @@ int fftfilt::run(const cmplx & in, cmplx **out) memcpy(freqdata, timedata, flen * sizeof(cmplx)); fft->ComplexFFT(freqdata); - for (int i = 0; i < flen; i++) + // Discard negative frequencies for ssb + for (int i = 0; i < flen2; i++) { freqdata[i] *= filter[i]; + freqdata[flen2 + i] = 0; + } fft->InverseComplexFFT(freqdata);