Exemple #1
0
void ModemNBFM::demodulate(ModemKit *kit, ModemIQData *input, AudioThreadInput *audioOut) {
    ModemKitAnalog *fmkit = (ModemKitAnalog *)kit;
    
    initOutputBuffers(fmkit, input);
    
    if (!bufSize) {
        input->decRefCount();
        return;
    }
    
    freqdem_demodulate_block(demodFM, &input->data[0], bufSize, &demodOutputData[0]);

    buildAudioOutput(fmkit, audioOut, false);
}
Exemple #2
0
void ModemFMStereo::demodulate(ModemKit *kit, ModemIQData *input, AudioThreadInput *audioOut) {
    ModemKitFMStereo *fmkit = (ModemKitFMStereo *)kit;
    size_t bufSize = input->data.size();
    liquid_float_complex u, v, w, x, y;
    
    double audio_resample_ratio = fmkit->audioResampleRatio;
    
    if (demodOutputData.size() != bufSize) {
        if (demodOutputData.capacity() < bufSize) {
            demodOutputData.reserve(bufSize);
        }
        demodOutputData.resize(bufSize);
    }
    
    size_t audio_out_size = (size_t)ceil((double) (bufSize) * audio_resample_ratio) + 512;
    
    freqdem_demodulate_block(demodFM, &input->data[0], bufSize, &demodOutputData[0]);
    
    if (resampledOutputData.size() != audio_out_size) {
        if (resampledOutputData.capacity() < audio_out_size) {
            resampledOutputData.reserve(audio_out_size);
        }
        resampledOutputData.resize(audio_out_size);
    }
    
    unsigned int numAudioWritten;
    
    msresamp_rrrf_execute(fmkit->audioResampler, &demodOutputData[0], bufSize, &resampledOutputData[0], &numAudioWritten);
    
    if (demodStereoData.size() != bufSize) {
        if (demodStereoData.capacity() < bufSize) {
            demodStereoData.reserve(bufSize);
        }
        demodStereoData.resize(bufSize);
    }
    
    float phase_error = 0;
    
    for (size_t i = 0; i < bufSize; i++) {
        // real -> complex
        firhilbf_r2c_execute(fmkit->firStereoR2C, demodOutputData[i], &x);
        
        // 19khz pilot band-pass
        iirfilt_crcf_execute(fmkit->iirStereoPilot, x, &v);
        nco_crcf_cexpf(fmkit->stereoPilot, &w);
        
        w.imag = -w.imag; // conjf(w)
        
        // 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(fmkit->stereoPilot, phase_error);
        nco_crcf_step(fmkit->stereoPilot);
        
        // 38khz down-mix
        nco_crcf_mix_down(fmkit->stereoPilot, x, &y);
        nco_crcf_mix_down(fmkit->stereoPilot, y, &x);
        
        // complex -> real
        firhilbf_c2r_execute(fmkit->firStereoC2R, x, &demodStereoData[i]);
    }
    
    //            std::cout << "[PLL] phase error: " << phase_error;
    //            std::cout << " freq:" << (((nco_crcf_get_frequency(stereoPilot) / (2.0 * M_PI)) * inp->sampleRate)) << std::endl;
    
    if (audio_out_size != resampledStereoData.size()) {
        if (resampledStereoData.capacity() < audio_out_size) {
            resampledStereoData.reserve(audio_out_size);
        }
        resampledStereoData.resize(audio_out_size);
    }
    
    msresamp_rrrf_execute(fmkit->stereoResampler, &demodStereoData[0], bufSize, &resampledStereoData[0], &numAudioWritten);
    
    audioOut->channels = 2;
    if (audioOut->data.capacity() < (numAudioWritten * 2)) {
        audioOut->data.reserve(numAudioWritten * 2);
    }
    audioOut->data.resize(numAudioWritten * 2);
    for (size_t i = 0; i < numAudioWritten; i++) {
        float l, r;
        float ld, rd;

        if (fmkit->demph) {
            iirfilt_rrrf_execute(fmkit->iirDemphL, 0.568f * (resampledOutputData[i] - (resampledStereoData[i])), &ld);
            iirfilt_rrrf_execute(fmkit->iirDemphR, 0.568f * (resampledOutputData[i] + (resampledStereoData[i])), &rd);
            
            firfilt_rrrf_push(fmkit->firStereoLeft, ld);
            firfilt_rrrf_execute(fmkit->firStereoLeft, &l);
            
            firfilt_rrrf_push(fmkit->firStereoRight, rd);
            firfilt_rrrf_execute(fmkit->firStereoRight, &r);
        } else {
            firfilt_rrrf_push(fmkit->firStereoLeft, 0.568f * (resampledOutputData[i] - (resampledStereoData[i])));
            firfilt_rrrf_execute(fmkit->firStereoLeft, &l);
            
            firfilt_rrrf_push(fmkit->firStereoRight, 0.568f * (resampledOutputData[i] + (resampledStereoData[i])));
            firfilt_rrrf_execute(fmkit->firStereoRight, &r);
        }
        
        audioOut->data[i * 2] = l;
        audioOut->data[i * 2 + 1] = r;
    }
}