Exemplo n.º 1
0
void ModemQPSK::demodulate(ModemKit *kit, ModemIQData *input, AudioThreadInput *audioOut) {
    ModemKitDigital *dkit = (ModemKitDigital *)kit;
    digitalStart(dkit, demodQPSK, input);

    for (size_t i = 0, bufSize = input->data.size(); i < bufSize; i++) {
        modem_demodulate(demodQPSK, input->data[i], &demodOutputDataDigital[i]);
    }
    updateDemodulatorLock(demodQPSK, 0.8f);
    
    digitalFinish(dkit, demodQPSK);
}
Exemplo n.º 2
0
// Helper function to keep code base small
void modem_test_demodstats(modulation_scheme _ms)
{
    // generate mod/demod
    modem mod   = modem_create(_ms);
    modem demod = modem_create(_ms);

    // run the test
    unsigned int i, s, M = 1 << modem_get_bps(mod);
    float complex x;
    float complex x_hat;    // rotated symbol
    float demodstats;
    float phi = 0.01f;

    for (i=0; i<M; i++) {
        // reset modem objects
        modem_reset(mod);
        modem_reset(demod);

        // modulate symbol
        modem_modulate(mod, i, &x);

        // ignore rare condition where modulated symbol is (0,0)
        // (e.g. APSK-8)
        if (cabsf(x) < 1e-3f) continue;

        // add phase offsets
        x_hat = x * cexpf( phi*_Complex_I);

        // demod positive phase signal, and ensure demodulator
        // maps to appropriate symbol
        modem_demodulate(demod, x_hat, &s);
        if (s != i)
            AUTOTEST_WARN("modem_test_demodstats(), output symbol does not match");

        demodstats = modem_get_demodulator_phase_error(demod);
        CONTEND_EXPRESSION(demodstats > 0.0f);
    }

    // repeat with negative phase error
    for (i=0; i<M; i++) {
        // reset modem objects
        modem_reset(mod);
        modem_reset(demod);

        // modulate symbol
        modem_modulate(mod, i, &x);

        // ignore rare condition where modulated symbol is (0,0)
        // (e.g. APSK-8)
        if (cabsf(x) < 1e-3f) continue;

        // add phase offsets
        x_hat = x * cexpf(-phi*_Complex_I);

        // demod positive phase signal, and ensure demodulator
        // maps to appropriate symbol
        modem_demodulate(demod, x_hat, &s);
        if (s != i)
            AUTOTEST_WARN("modem_test_demodstats(), output symbol does not match");

        demodstats = modem_get_demodulator_phase_error(demod);
        CONTEND_EXPRESSION(demodstats < 0.0f);
    }

    // clean up allocated objects up
    modem_destroy(mod);
    modem_destroy(demod);
}
Exemplo n.º 3
0
int main(int argc, char*argv[])
{
    // set random number generator seed
    srand(time(NULL));

    // options
    unsigned int M = 64;                // number of subcarriers
    unsigned int cp_len = 16;           // cyclic prefix length
    modulation_scheme ms = LIQUID_MODEM_BPSK;
    float SNRdB = 6.5f;                 // signal-to-noise ratio [dB]
    unsigned int hc_len = 1;            // channel impulse response length
    unsigned int num_symbols = 40;      // number of OFDM symbols

    // get options
    int dopt;
    while((dopt = getopt(argc,argv,"hs:M:C:m:n:c:")) != EOF){
        switch (dopt) {
        case 'h': usage(); return 0;
        case 's': SNRdB  = atof(optarg); break;
        case 'M': M      = atoi(optarg); break;
        case 'C': cp_len = atoi(optarg); break;
        case 'm':
            ms = liquid_getopt_str2mod(optarg);
            if (ms == LIQUID_MODEM_UNKNOWN) {
                fprintf(stderr,"error: %s, unknown/unsupported mod. scheme: %s\n", argv[0], optarg);
                exit(-1);
            }
            break;
        case 'n': num_symbols = atoi(optarg); break;
        case 'c': hc_len      = atoi(optarg); break;
        default:
            exit(-1);
        }
    }

    unsigned int i;

    // validate options
    if (M < 4) {
        fprintf(stderr,"error: %s, must have at least 4 subcarriers\n", argv[0]);
        exit(1);
    } else if (hc_len == 0) {
        fprintf(stderr,"error: %s, must have at least 1 channel tap\n", argv[0]);
        exit(1);
    }

    // derived values
    unsigned int symbol_len = M + cp_len;
    float nstd = powf(10.0f, -SNRdB/20.0f);
    float fft_gain = 1.0f / sqrtf(M);   // 'gain' due to taking FFT
    
    // buffers
    unsigned int sym_in[M];             // input data symbols
    unsigned int sym_out[M];            // output data symbols
    float complex x[M];                 // time-domain buffer
    float complex X[M];                 // freq-domain buffer
    float complex buffer[symbol_len];   // 

    // create modulator/demodulator objects
    modem mod   = modem_create(ms);
    modem demod = modem_create(ms);
    unsigned int bps = modem_get_bps(mod);  // modem bits/symbol

    // create channel filter (random taps)
    float complex hc[hc_len];
    hc[0] = 1.0f;
    for (i=1; i<hc_len; i++)
        hc[i] = 0.1f * (randnf() + _Complex_I*randnf());
    firfilt_cccf fchannel = firfilt_cccf_create(hc, hc_len);

    //
    unsigned int n;
    unsigned int num_bit_errors = 0;
    for (n=0; n<num_symbols; n++) {
        // generate random data symbols and modulate onto subcarriers
        for (i=0; i<M; i++) {
            sym_in[i] = rand() % (1<<bps);

            modem_modulate(mod, sym_in[i], &X[i]);
        }

        // run inverse transform
        fft_run(M, X, x, LIQUID_FFT_BACKWARD, 0);

        // scale by FFT gain so E{|x|^2} = 1
        for (i=0; i<M; i++)
            x[i] *= fft_gain;

        // apply channel impairments
        for (i=0; i<M + cp_len; i++) {
            // push samples through channel filter, starting with cyclic prefix
            firfilt_cccf_push(fchannel, x[(M-cp_len+i)%M]);

            // compute output
            firfilt_cccf_execute(fchannel, &buffer[i]);

            // add noise
            buffer[i] += nstd*( randnf() + _Complex_I*randnf() ) * M_SQRT1_2;
        }

        // run forward transform
        fft_run(M, &buffer[cp_len], X, LIQUID_FFT_FORWARD, 0);

        // TODO : apply equalizer to 'X' here

        // demodulate and compute bit errors
        for (i=0; i<M; i++) {
            // scale by fft size
            X[i] *= fft_gain;

            modem_demodulate(demod, X[i], &sym_out[i]);

            num_bit_errors += liquid_count_ones(sym_in[i] ^ sym_out[i]);
        }
    }

    // destroy objects
    modem_destroy(mod);
    modem_destroy(demod);
    firfilt_cccf_destroy(fchannel);

    // print results
    unsigned int total_bits = M*bps*num_symbols;
    float ber = (float)num_bit_errors / (float)total_bits;
    printf("  bit errors : %6u / %6u (%12.4e)\n", num_bit_errors, total_bits, ber);

    printf("done.\n");
    return 0;
}
Exemplo n.º 4
0
// receive payload data
void ofdmflexframesync_rxpayload(ofdmflexframesync _q,
                                 float complex * _X)
{
    // demodulate paylod symbols
    unsigned int i;
    int sctype;
    for (i=0; i<_q->M; i++) {
        // subcarrier type (PILOT/NULL/DATA)
        sctype = _q->p[i];

        // ignore pilot and null subcarriers
        if (sctype == OFDMFRAME_SCTYPE_DATA) {
            // unload payload symbols
            unsigned int sym;
            modem_demodulate(_q->mod_payload, _X[i], &sym);

            // pack decoded symbol into array
            liquid_pack_array(_q->payload_enc,
                              _q->payload_enc_len,
                              _q->payload_buffer_index,
                              _q->bps_payload,
                              sym);

            // increment...
            _q->payload_buffer_index += _q->bps_payload;

            // increment symbol counter
            _q->payload_symbol_index++;

            if (_q->payload_symbol_index == _q->payload_mod_len) {
                // payload extracted

                // decode payload
                _q->payload_valid = packetizer_decode(_q->p_payload, _q->payload_enc, _q->payload_dec);
#if DEBUG_OFDMFLEXFRAMESYNC
                printf("****** payload extracted [%s]\n", _q->payload_valid ? "valid" : "INVALID!");
#endif

                // ignore callback if set to NULL
                if (_q->callback == NULL) {
                    ofdmflexframesync_reset(_q);
                    break;
                }

                // set framestats internals
                _q->framestats.rssi             = ofdmframesync_get_rssi(_q->fs);
                _q->framestats.cfo              = ofdmframesync_get_cfo(_q->fs);
                _q->framestats.framesyms        = NULL;
                _q->framestats.num_framesyms    = 0;
                _q->framestats.mod_scheme       = _q->ms_payload;
                _q->framestats.mod_bps          = _q->bps_payload;
                _q->framestats.check            = _q->check;
                _q->framestats.fec0             = _q->fec0;
                _q->framestats.fec1             = _q->fec1;

                // invoke callback method
                _q->callback(_q->header,
                             _q->header_valid,
                             _q->payload_dec,
                             _q->payload_len,
                             _q->payload_valid,
                             _q->framestats,
                             _q->userdata);


                // reset object
                ofdmflexframesync_reset(_q);
                break;
            }
        }
    }
}
// Helper function to keep code base small
void modem_demodulate_bench(struct rusage *_start,
                            struct rusage *_finish,
                            unsigned long int *_num_iterations,
                            modulation_scheme _ms)
{
    // normalize number of iterations
    switch (_ms) {
    case LIQUID_MODEM_UNKNOWN:
        fprintf(stderr,"error: modem_demodulate_bench(), unknown modem scheme\n");
        exit(1);
    case LIQUID_MODEM_BPSK:     *_num_iterations *= 2;      break;
    case LIQUID_MODEM_QPSK:     *_num_iterations *= 2;      break;
    case LIQUID_MODEM_OOK:      *_num_iterations *= 2;      break;
    case LIQUID_MODEM_SQAM32:   *_num_iterations /= 10;     break;
    case LIQUID_MODEM_SQAM128:  *_num_iterations /= 20;     break;
    case LIQUID_MODEM_V29:      *_num_iterations /= 16;     break;
    case LIQUID_MODEM_ARB16OPT: *_num_iterations /= 8;      break;
    case LIQUID_MODEM_ARB32OPT: *_num_iterations /= 16;     break;
    case LIQUID_MODEM_ARB64OPT: *_num_iterations /= 32;     break;
    case LIQUID_MODEM_ARB128OPT: *_num_iterations /= 64;    break;
    case LIQUID_MODEM_ARB256OPT: *_num_iterations /= 128;   break;
    case LIQUID_MODEM_ARB64VT:  *_num_iterations /= 64;     break;
    default:;
        *_num_iterations /= 8;
    }

    if (*_num_iterations < 1) *_num_iterations = 1;


    // initialize modulator
    modem demod = modem_create(_ms);

    unsigned long int i;

    // generate input vector to demodulate (spiral)
    float complex x[20];
    for (i=0; i<20; i++)
        x[i] = 0.07 * i * cexpf(_Complex_I*2*M_PI*0.1*i);

    unsigned int symbol_out;

    // start trials
    getrusage(RUSAGE_SELF, _start);
    for (i=0; i<(*_num_iterations); i++) {
        modem_demodulate(demod, x[ 0], &symbol_out);
        modem_demodulate(demod, x[ 1], &symbol_out);
        modem_demodulate(demod, x[ 2], &symbol_out);
        modem_demodulate(demod, x[ 3], &symbol_out);
        modem_demodulate(demod, x[ 4], &symbol_out);
        modem_demodulate(demod, x[ 5], &symbol_out);
        modem_demodulate(demod, x[ 6], &symbol_out);
        modem_demodulate(demod, x[ 7], &symbol_out);
        modem_demodulate(demod, x[ 8], &symbol_out);
        modem_demodulate(demod, x[ 9], &symbol_out);
        modem_demodulate(demod, x[10], &symbol_out);
        modem_demodulate(demod, x[11], &symbol_out);
        modem_demodulate(demod, x[12], &symbol_out);
        modem_demodulate(demod, x[13], &symbol_out);
        modem_demodulate(demod, x[14], &symbol_out);
        modem_demodulate(demod, x[15], &symbol_out);
        modem_demodulate(demod, x[16], &symbol_out);
        modem_demodulate(demod, x[17], &symbol_out);
        modem_demodulate(demod, x[18], &symbol_out);
        modem_demodulate(demod, x[19], &symbol_out);
    }
    getrusage(RUSAGE_SELF, _finish);
    *_num_iterations *= 20;

    modem_destroy(demod);
}
Exemplo n.º 6
0
// execute synchronizer, receiving payload
//  _q     :   frame synchronizer object
//  _x      :   input sample
//  _sym    :   demodulated symbol
void flexframesync_execute_rxpayload(flexframesync _q,
                                     float complex _x)
{
    // mix signal down
    float complex y;
    nco_crcf_mix_down(_q->nco_coarse, _x*0.5f/_q->gamma_hat, &y);
    nco_crcf_step(_q->nco_coarse);

    // update symbol synchronizer
    float complex mf_out = 0.0f;
    int sample_available = flexframesync_update_symsync(_q, y, &mf_out);

    // compute output if timeout
    if (sample_available) {

        // push through fine-tuned nco
        nco_crcf_mix_down(_q->nco_fine, mf_out, &mf_out);
        // save payload symbols for callback (up to 256 values)
        if (_q->payload_counter < 256)
            _q->payload_sym[_q->payload_counter] = mf_out;
        
        // demodulate
        unsigned int sym_out = 0;
        modem_demodulate(_q->demod_payload, mf_out, &sym_out);
        _q->payload_mod[_q->payload_counter] = (unsigned char)sym_out;

        // update phase-locked loop and fine-tuned NCO
        float phase_error = modem_get_demodulator_phase_error(_q->demod_payload);
        nco_crcf_pll_step(_q->nco_fine, phase_error);
        nco_crcf_step(_q->nco_fine);

        // increment counter
        _q->payload_counter++;

        if (_q->payload_counter == _q->payload_mod_len) {
            // decode payload and invoke callback
            flexframesync_decode_payload(_q);

            // invoke callback
            if (_q->callback != NULL) {
                // set framestats internals
                _q->framestats.evm           = 20*log10f(sqrtf(_q->framestats.evm / FLEXFRAME_H_SYM));
                _q->framestats.rssi          = 20*log10f(_q->gamma_hat);
                _q->framestats.cfo           = nco_crcf_get_frequency(_q->nco_coarse) +
                                               nco_crcf_get_frequency(_q->nco_fine) / 2.0f; //(float)(_q->k);
                _q->framestats.framesyms     = _q->payload_sym;
                _q->framestats.num_framesyms = _q->payload_mod_len > 256 ? 256 : _q->payload_mod_len;
                _q->framestats.mod_scheme    = _q->ms_payload;
                _q->framestats.mod_bps       = _q->bps_payload;
                _q->framestats.check         = _q->check;
                _q->framestats.fec0          = _q->fec0;
                _q->framestats.fec1          = _q->fec1;

                // invoke callback method
                _q->callback(_q->header,
                             _q->header_valid,
                             _q->payload_dec,
                             _q->payload_dec_len,
                             _q->payload_valid,
                             _q->framestats,
                             _q->userdata);
            }

            // reset frame synchronizer
            flexframesync_reset(_q);
            return;
        }
    }
}
Exemplo n.º 7
0
// receive header data
void ofdmflexframesync_rxheader(ofdmflexframesync _q,
                                float complex * _X)
{
#if DEBUG_OFDMFLEXFRAMESYNC
    printf("  ofdmflexframesync extracting header...\n");
#endif

    // demodulate header symbols
    unsigned int i;
    int sctype;
    for (i=0; i<_q->M; i++) {
        // subcarrier type (PILOT/NULL/DATA)
        sctype = _q->p[i];

        // ignore pilot and null subcarriers
        if (sctype == OFDMFRAME_SCTYPE_DATA) {
            // unload header symbols
            // demodulate header symbol
            unsigned int sym;
#if OFDMFLEXFRAME_H_SOFT
            modem_demodulate_soft(_q->mod_header, _X[i], &sym, &_q->header_mod[OFDMFLEXFRAME_H_BPS*_q->header_symbol_index]);
#else
            modem_demodulate(_q->mod_header, _X[i], &sym);
            _q->header_mod[_q->header_symbol_index] = sym;
#endif
            _q->header_symbol_index++;
            //printf("  extracting symbol %3u / %3u (x = %8.5f + j%8.5f)\n", _q->header_symbol_index, OFDMFLEXFRAME_H_SYM, crealf(_X[i]), cimagf(_X[i]));

            // get demodulator error vector magnitude
            float evm = modem_get_demodulator_evm(_q->mod_header);
            _q->evm_hat += evm*evm;

            // header extracted
            if (_q->header_symbol_index == OFDMFLEXFRAME_H_SYM) {
                // decode header
                ofdmflexframesync_decode_header(_q);

                // compute error vector magnitude estimate
                _q->framestats.evm = 10*log10f( _q->evm_hat/OFDMFLEXFRAME_H_SYM );

                // invoke callback if header is invalid
                if (_q->header_valid)
                    _q->state = OFDMFLEXFRAMESYNC_STATE_PAYLOAD;
                else {
                    //printf("**** header invalid!\n");
                    // set framestats internals
                    _q->framestats.rssi             = ofdmframesync_get_rssi(_q->fs);
                    _q->framestats.cfo              = ofdmframesync_get_cfo(_q->fs);
                    _q->framestats.framesyms        = NULL;
                    _q->framestats.num_framesyms    = 0;
                    _q->framestats.mod_scheme       = LIQUID_MODEM_UNKNOWN;
                    _q->framestats.mod_bps          = 0;
                    _q->framestats.check            = LIQUID_CRC_UNKNOWN;
                    _q->framestats.fec0             = LIQUID_FEC_UNKNOWN;
                    _q->framestats.fec1             = LIQUID_FEC_UNKNOWN;

                    // invoke callback method
                    _q->callback(_q->header,
                                 _q->header_valid,
                                 NULL,
                                 0,
                                 0,
                                 _q->framestats,
                                 _q->userdata);

                    ofdmflexframesync_reset(_q);
                }
                break;
            }
        }
    }
}
Exemplo n.º 8
0
int main(int argc, char*argv[]) {
    srand( time(NULL) );
    // parameters
    float phase_offset = M_PI/10;
    float frequency_offset = 0.001f;
    float SNRdB = 30.0f;
    float pll_bandwidth = 0.02f;
    modulation_scheme ms = LIQUID_MODEM_QPSK;
    unsigned int n=256;     // number of iterations

    int dopt;
    while ((dopt = getopt(argc,argv,"uhs:b:n:P:F:m:")) != EOF) {
        switch (dopt) {
        case 'u':
        case 'h':   usage();    return 0;
        case 's':   SNRdB = atof(optarg);           break;
        case 'b':   pll_bandwidth = atof(optarg);   break;
        case 'n':   n = atoi(optarg);               break;
        case 'P':   phase_offset = atof(optarg);    break;
        case 'F':   frequency_offset= atof(optarg); break;
        case 'm':
            ms = liquid_getopt_str2mod(optarg);
            if (ms == LIQUID_MODEM_UNKNOWN) {
                fprintf(stderr,"error: %s, unknown/unsupported modulation scheme \"%s\"\n", argv[0], optarg);
                return 1;
            }
            break;
        default:
            exit(1);
        }
    }
    unsigned int d=n/32;      // print every "d" lines

    FILE * fid = fopen(OUTPUT_FILENAME,"w");
    fprintf(fid, "%% %s : auto-generated file\n", OUTPUT_FILENAME);
    fprintf(fid, "clear all;\n");
    fprintf(fid, "phi=zeros(1,%u);\n",n);
    fprintf(fid, "r=zeros(1,%u);\n",n);

    // objects
    nco_crcf nco_tx = nco_crcf_create(LIQUID_VCO);
    nco_crcf nco_rx = nco_crcf_create(LIQUID_VCO);

    modem mod   = modem_create(ms);
    modem demod = modem_create(ms);

    unsigned int bps = modem_get_bps(mod);

    // initialize objects
    nco_crcf_set_phase(nco_tx, phase_offset);
    nco_crcf_set_frequency(nco_tx, frequency_offset);
    nco_crcf_pll_set_bandwidth(nco_rx, pll_bandwidth);

    float noise_power = powf(10.0f, -SNRdB/20.0f);

    // print parameters
    printf("PLL example :\n");
    printf("modem : %u-%s\n", 1<<bps, modulation_types[ms].name);
    printf("frequency offset: %6.3f, phase offset: %6.3f, SNR: %6.2fdB, pll b/w: %6.3f\n",
            frequency_offset, phase_offset, SNRdB, pll_bandwidth);

    // run loop
    unsigned int i, M=1<<bps, sym_in, sym_out, num_errors=0;
    float phase_error;
    float complex x, r, v, noise;
    for (i=0; i<n; i++) {
        // generate random symbol
        sym_in = rand() % M;

        // modulate
        modem_modulate(mod, sym_in, &x);

        // channel
        //r = nco_crcf_cexpf(nco_tx);
        nco_crcf_mix_up(nco_tx, x, &r);

        // add complex white noise
        crandnf(&noise);
        r += noise * noise_power;

        // 
        //v = nco_crcf_cexpf(nco_rx);
        nco_crcf_mix_down(nco_rx, r, &v);

        // demodulate
        modem_demodulate(demod, v, &sym_out);
        num_errors += count_bit_errors(sym_in, sym_out);

        // error estimation
        //phase_error = cargf(r*conjf(v));
        phase_error = modem_get_demodulator_phase_error(demod);

        // perfect error estimation
        //phase_error = nco_tx->theta - nco_rx->theta;

        // print every line in a format that octave can read
        fprintf(fid, "phi(%u) = %10.6E;\n", i+1, phase_error);
        fprintf(fid, "r(%u) = %10.6E + j*%10.6E;\n",
                i+1, crealf(v), cimagf(v));

        if ((i+1)%d == 0 || i==n-1) {
            printf("  %4u: e_hat : %6.3f, phase error : %6.3f, freq error : %6.3f\n",
                    i+1,                                // iteration
                    phase_error,                        // estimated phase error
                    nco_crcf_get_phase(nco_tx) - nco_crcf_get_phase(nco_rx),// true phase error
                    nco_crcf_get_frequency(nco_tx) - nco_crcf_get_frequency(nco_rx)// true frequency error
                  );
        }

        // update tx nco object
        nco_crcf_step(nco_tx);

        // update pll
        nco_crcf_pll_step(nco_rx, phase_error);

        // update rx nco object
        nco_crcf_step(nco_rx);
    }

    fprintf(fid, "figure;\n");
    fprintf(fid, "plot(1:length(phi),phi,'LineWidth',2,'Color',[0 0.25 0.5]);\n");
    fprintf(fid, "xlabel('Symbol Index');\n");
    fprintf(fid, "ylabel('Phase Error [radians]');\n");
    fprintf(fid, "grid on;\n");

    fprintf(fid, "t0 = round(0.25*length(r));\n");
    fprintf(fid, "figure;\n");
    fprintf(fid, "plot(r(1:t0),'x','Color',[0.6 0.6 0.6],r(t0:end),'x','Color',[0 0.25 0.5]);\n");
    fprintf(fid, "grid on;\n");
    fprintf(fid, "axis([-1.5 1.5 -1.5 1.5]);\n");
    fprintf(fid, "axis('square');\n");
    fprintf(fid, "xlabel('In-Phase');\n");
    fprintf(fid, "ylabel('Quadrature');\n");
    fprintf(fid, "legend(['first 25%%'],['last 75%%'],1);\n");
    fclose(fid);

    printf("results written to %s.\n",OUTPUT_FILENAME);

    nco_crcf_destroy(nco_tx);
    nco_crcf_destroy(nco_rx);

    modem_destroy(mod);
    modem_destroy(demod);

    printf("bit errors: %u / %u\n", num_errors, bps*n);
    printf("done.\n");
    return 0;
}
Exemplo n.º 9
0
// execute synchronizer, receiving header
//  _q      :   frame synchronizer object
//  _x      :   input sample
void flexframesync_execute_rxheader(flexframesync _q,
                                    float complex _x)
{
    // mix signal down
    float complex y;
    nco_crcf_mix_down(_q->nco_coarse, _x*0.5f/_q->gamma_hat, &y);
    nco_crcf_step(_q->nco_coarse);

    // update symbol synchronizer
    float complex mf_out = 0.0f;
    int sample_available = flexframesync_update_symsync(_q, y, &mf_out);

    // compute output if timeout
    if (sample_available) {
        // push through fine-tuned nco
        nco_crcf_mix_down(_q->nco_fine, mf_out, &mf_out);

#if DEBUG_FLEXFRAMESYNC
        if (_q->debug_enabled)
            _q->header_sym[_q->header_counter] = mf_out;
#endif
        
        // demodulate
        unsigned int sym_out = 0;
#if DEMOD_HEADER_SOFT
        unsigned char bpsk_soft_bit = 0;
        modem_demodulate_soft(_q->demod_header, mf_out, &sym_out, &bpsk_soft_bit);
        _q->header_mod[_q->header_counter] = bpsk_soft_bit;
#else
        modem_demodulate(_q->demod_header, mf_out, &sym_out);
        _q->header_mod[_q->header_counter] = (unsigned char)sym_out;
#endif

        // update phase-locked loop and fine-tuned NCO
        float phase_error = modem_get_demodulator_phase_error(_q->demod_header);
        nco_crcf_pll_step(_q->nco_fine, phase_error);
        nco_crcf_step(_q->nco_fine);

        // update error vector magnitude
        float evm = modem_get_demodulator_evm(_q->demod_header);
        _q->framestats.evm += evm*evm;

        // increment counter
        _q->header_counter++;

        if (_q->header_counter == FLEXFRAME_H_SYM) {
            // decode header and invoke callback
            flexframesync_decode_header(_q);
            
            // invoke callback if header is invalid
            if (!_q->header_valid && _q->callback != NULL) {
                // set framestats internals
                _q->framestats.evm           = 20*log10f(sqrtf(_q->framestats.evm / FLEXFRAME_H_SYM));
                _q->framestats.rssi          = 20*log10f(_q->gamma_hat);
                _q->framestats.cfo           = nco_crcf_get_frequency(_q->nco_coarse) +
                                               nco_crcf_get_frequency(_q->nco_fine) / 2.0f; //(float)(_q->k);
                _q->framestats.framesyms     = NULL;
                _q->framestats.num_framesyms = 0;
                _q->framestats.mod_scheme    = LIQUID_MODEM_UNKNOWN;
                _q->framestats.mod_bps       = 0;
                _q->framestats.check         = LIQUID_CRC_UNKNOWN;
                _q->framestats.fec0          = LIQUID_FEC_UNKNOWN;
                _q->framestats.fec1          = LIQUID_FEC_UNKNOWN;

                // invoke callback method
                _q->callback(_q->header,
                             _q->header_valid,
                             NULL,
                             0,
                             0,
                             _q->framestats,
                             _q->userdata);
            }
            
            if (!_q->header_valid) {
                flexframesync_reset(_q);
                return;
            }

            
            // update state
            _q->state = STATE_RXPAYLOAD;
        }
    }
}
Exemplo n.º 10
0
// execute synchronizer, receiving payload
//  _q      :   frame synchronizer object
//  _x      :   input sample
//  _sym    :   demodulated symbol
void flexframesync_execute_rxpayload(flexframesync _q,
                                     float complex _x)
{
    // step synchronizer
    float complex mf_out = 0.0f;
    int sample_available = flexframesync_step(_q, _x, &mf_out);

    // compute output if timeout
    if (sample_available) {
        // TODO: clean this up
        // mix down with fine-tuned oscillator
        nco_crcf_mix_down(_q->pll, mf_out, &mf_out);
        // track phase, accumulate error-vector magnitude
        unsigned int sym;
        modem_demodulate(_q->payload_demod, mf_out, &sym);
        float phase_error = modem_get_demodulator_phase_error(_q->payload_demod);
        float evm         = modem_get_demodulator_evm        (_q->payload_demod);
        nco_crcf_pll_step(_q->pll, phase_error);
        nco_crcf_step(_q->pll);
        _q->framesyncstats.evm += evm*evm;

        // save payload symbols (modem input/output)
        _q->payload_sym[_q->symbol_counter] = mf_out;

        // increment counter
        _q->symbol_counter++;

        if (_q->symbol_counter == _q->payload_sym_len) {
            // decode payload
            _q->payload_valid = qpacketmodem_decode(_q->payload_decoder,
                                                    _q->payload_sym,
                                                    _q->payload_dec);

            // update statistics
            _q->framedatastats.num_frames_detected++;
            _q->framedatastats.num_headers_valid++;
            _q->framedatastats.num_payloads_valid += _q->payload_valid;
            _q->framedatastats.num_bytes_received += _q->payload_dec_len;

            // invoke callback
            if (_q->callback != NULL) {
                // set framestats internals
                int ms = qpacketmodem_get_modscheme(_q->payload_decoder);
                _q->framesyncstats.evm           = 10*log10f(_q->framesyncstats.evm / (float)_q->payload_sym_len);
                _q->framesyncstats.rssi          = 20*log10f(_q->gamma_hat);
                _q->framesyncstats.cfo           = nco_crcf_get_frequency(_q->mixer);
                _q->framesyncstats.framesyms     = _q->payload_sym;
                _q->framesyncstats.num_framesyms = _q->payload_sym_len;
                _q->framesyncstats.mod_scheme    = ms;
                _q->framesyncstats.mod_bps       = modulation_types[ms].bps;
                _q->framesyncstats.check         = qpacketmodem_get_crc(_q->payload_decoder);
                _q->framesyncstats.fec0          = qpacketmodem_get_fec0(_q->payload_decoder);
                _q->framesyncstats.fec1          = qpacketmodem_get_fec1(_q->payload_decoder);

                // invoke callback method
                _q->callback(_q->header_dec,
                             _q->header_valid,
                             _q->payload_dec,
                             _q->payload_dec_len,
                             _q->payload_valid,
                             _q->framesyncstats,
                             _q->userdata);
            }

            // reset frame synchronizer
            flexframesync_reset(_q);
            return;
        }
    }
}
int main(int argc, char*argv[])
{
    srand(time(NULL));

    // options
    unsigned int num_symbols=500;   // number of symbols to observe
    float SNRdB = 30.0f;            // signal-to-noise ratio [dB]
    unsigned int hc_len=5;          // channel filter length
    unsigned int k=2;               // matched filter samples/symbol
    unsigned int m=3;               // matched filter delay (symbols)
    float beta=0.3f;                // matched filter excess bandwidth factor
    unsigned int p=3;               // equalizer length (symbols, hp_len = 2*k*p+1)
    float mu = 0.08f;               // learning rate

    // modulation type/depth
    modulation_scheme ms = LIQUID_MODEM_QPSK;

    int dopt;
    while ((dopt = getopt(argc,argv,"hn:s:c:k:m:b:p:u:M:")) != EOF) {
        switch (dopt) {
        case 'h': usage();                      return 0;
        case 'n': num_symbols   = atoi(optarg); break;
        case 's': SNRdB         = atof(optarg); break;
        case 'c': hc_len        = atoi(optarg); break;
        case 'k': k             = atoi(optarg); break;
        case 'm': m             = atoi(optarg); break;
        case 'b': beta          = atof(optarg); break;
        case 'p': p             = atoi(optarg); break;
        case 'u': mu            = atof(optarg); break;
        case 'M':
            ms = liquid_getopt_str2mod(optarg);
            if (ms == LIQUID_MODEM_UNKNOWN) {
                fprintf(stderr,"error: %s, unknown/unsupported modulation scheme '%s'\n", argv[0], optarg);
                return 1;
            }
            break;
        default:
            exit(1);
        }
    }

    // validate input
    if (num_symbols == 0) {
        fprintf(stderr,"error: %s, number of symbols must be greater than zero\n", argv[0]);
        exit(1);
    } else if (hc_len == 0) {
        fprintf(stderr,"error: %s, channel must have at least 1 tap\n", argv[0]);
        exit(1);
    } else if (k < 2) {
        fprintf(stderr,"error: %s, samples/symbol must be at least 2\n", argv[0]);
        exit(1);
    } else if (m == 0) {
        fprintf(stderr,"error: %s, filter semi-length must be at least 1 symbol\n", argv[0]);
        exit(1);
    } else if (beta < 0.0f || beta > 1.0f) {
        fprintf(stderr,"error: %s, filter excess bandwidth must be in [0,1]\n", argv[0]);
        exit(1);
    } else if (p == 0) {
        fprintf(stderr,"error: %s, equalizer semi-length must be at least 1 symbol\n", argv[0]);
        exit(1);
    } else if (mu < 0.0f || mu > 1.0f) {
        fprintf(stderr,"error: %s, equalizer learning rate must be in [0,1]\n", argv[0]);
        exit(1);
    }

    // derived values
    unsigned int hm_len = 2*k*m+1;   // matched filter length
    unsigned int hp_len = 2*k*p+1;   // equalizer filter length
    unsigned int num_samples = k*num_symbols;

    // bookkeeping variables
    float complex sym_tx[num_symbols];  // transmitted data sequence
    float complex x[num_samples];       // interpolated time series
    float complex y[num_samples];       // channel output
    float complex z[num_samples];       // equalized output

    float hm[hm_len];                   // matched filter response
    float complex hc[hc_len];           // channel filter coefficients
    float complex hp[hp_len];           // equalizer filter coefficients

    unsigned int i;

    // generate matched filter response
    liquid_firdes_rnyquist(LIQUID_FIRFILT_RRC, k, m, beta, 0.0f, hm);
    firinterp_crcf interp = firinterp_crcf_create(k, hm, hm_len);

    // create the modem objects
    modem mod   = modem_create(ms);
    modem demod = modem_create(ms);
    unsigned int M = 1 << modem_get_bps(mod);

    // generate channel impulse response, filter
    hc[0] = 1.0f;
    for (i=1; i<hc_len; i++)
        hc[i] = 0.09f*(randnf() + randnf()*_Complex_I);
    firfilt_cccf fchannel = firfilt_cccf_create(hc, hc_len);

    // generate random symbols
    for (i=0; i<num_symbols; i++)
        modem_modulate(mod, rand()%M, &sym_tx[i]);

    // interpolate
    for (i=0; i<num_symbols; i++)
        firinterp_crcf_execute(interp, sym_tx[i], &x[i*k]);
    
    // push through channel
    float nstd = powf(10.0f, -SNRdB/20.0f);
    for (i=0; i<num_samples; i++) {
        firfilt_cccf_push(fchannel, x[i]);
        firfilt_cccf_execute(fchannel, &y[i]);

        // add noise
        y[i] += nstd*(randnf() + randnf()*_Complex_I)*M_SQRT1_2;
    }

    // push through equalizer
    // create equalizer, intialized with square-root Nyquist filter
    eqlms_cccf eq = eqlms_cccf_create_rnyquist(LIQUID_FIRFILT_RRC, k, p, beta, 0.0f);
    eqlms_cccf_set_bw(eq, mu);

    // get initialized weights
    eqlms_cccf_get_weights(eq, hp);

    // filtered error vector magnitude (emperical RMS error)
    float evm_hat = 0.03f;

    float complex d_hat = 0.0f;
    for (i=0; i<num_samples; i++) {
        // print filtered evm (emperical rms error)
        if ( ((i+1)%50)==0 )
            printf("%4u : rms error = %12.8f dB\n", i+1, 10*log10(evm_hat));

        eqlms_cccf_push(eq, y[i]);
        eqlms_cccf_execute(eq, &d_hat);

        // store output
        z[i] = d_hat;

        // decimate by k
        if ( (i%k) != 0 ) continue;

        // estimate transmitted signal
        unsigned int sym_out;   // output symbol
        float complex d_prime;  // estimated input sample
        modem_demodulate(demod, d_hat, &sym_out);
        modem_get_demodulator_sample(demod, &d_prime);

        // update equalizer
        eqlms_cccf_step(eq, d_prime, d_hat);

        // update filtered evm estimate
        float evm = crealf( (d_prime-d_hat)*conjf(d_prime-d_hat) );
        evm_hat = 0.98f*evm_hat + 0.02f*evm;
    }

    // get equalizer weights
    eqlms_cccf_get_weights(eq, hp);

    // destroy objects
    eqlms_cccf_destroy(eq);
    firinterp_crcf_destroy(interp);
    firfilt_cccf_destroy(fchannel);
    modem_destroy(mod);
    modem_destroy(demod);

    // 
    // export output
    //
    FILE * fid = fopen(OUTPUT_FILENAME,"w");
    fprintf(fid,"%% %s : auto-generated file\n\n", OUTPUT_FILENAME);
    fprintf(fid,"clear all\n");
    fprintf(fid,"close all\n");

    fprintf(fid,"k = %u;\n", k);
    fprintf(fid,"m = %u;\n", m);
    fprintf(fid,"num_symbols = %u;\n", num_symbols);
    fprintf(fid,"num_samples = num_symbols*k;\n");

    // save transmit matched-filter response
    fprintf(fid,"hm_len = 2*k*m+1;\n");
    fprintf(fid,"hm = zeros(1,hm_len);\n");
    for (i=0; i<hm_len; i++)
        fprintf(fid,"hm(%4u) = %12.4e;\n", i+1, hm[i]);

    // save channel impulse response
    fprintf(fid,"hc_len = %u;\n", hc_len);
    fprintf(fid,"hc = zeros(1,hc_len);\n");
    for (i=0; i<hc_len; i++)
        fprintf(fid,"hc(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(hc[i]), cimagf(hc[i]));

    // save equalizer response
    fprintf(fid,"hp_len = %u;\n", hp_len);
    fprintf(fid,"hp = zeros(1,hp_len);\n");
    for (i=0; i<hp_len; i++)
        fprintf(fid,"hp(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(hp[i]), cimagf(hp[i]));

    // save sample sets
    fprintf(fid,"x = zeros(1,num_samples);\n");
    fprintf(fid,"y = zeros(1,num_samples);\n");
    fprintf(fid,"z = zeros(1,num_samples);\n");
    for (i=0; i<num_samples; i++) {
        fprintf(fid,"x(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(x[i]), cimagf(x[i]));
        fprintf(fid,"y(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(y[i]), cimagf(y[i]));
        fprintf(fid,"z(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(z[i]), cimagf(z[i]));
    }

    // plot time response
    fprintf(fid,"t = 0:(num_samples-1);\n");
    fprintf(fid,"tsym = 1:k:num_samples;\n");
    fprintf(fid,"figure;\n");
    fprintf(fid,"plot(t,real(z),...\n");
    fprintf(fid,"     t(tsym),real(z(tsym)),'x');\n");

    // plot constellation
    fprintf(fid,"tsym0 = tsym(1:(length(tsym)/2));\n");
    fprintf(fid,"tsym1 = tsym((length(tsym)/2):end);\n");
    fprintf(fid,"figure;\n");
    fprintf(fid,"plot(real(z(tsym0)),imag(z(tsym0)),'x','Color',[1 1 1]*0.7,...\n");
    fprintf(fid,"     real(z(tsym1)),imag(z(tsym1)),'x','Color',[1 1 1]*0.0);\n");
    fprintf(fid,"xlabel('In-Phase');\n");
    fprintf(fid,"ylabel('Quadrature');\n");
    fprintf(fid,"axis([-1 1 -1 1]*1.5);\n");
    fprintf(fid,"axis square;\n");
    fprintf(fid,"grid on;\n");

    // compute composite response
    fprintf(fid,"g  = real(conv(conv(hm,hc),hp));\n");

    // plot responses
    fprintf(fid,"nfft = 1024;\n");
    fprintf(fid,"f = [0:(nfft-1)]/nfft - 0.5;\n");
    fprintf(fid,"Hm = 20*log10(abs(fftshift(fft(hm/k,nfft))));\n");
    fprintf(fid,"Hc = 20*log10(abs(fftshift(fft(hc,  nfft))));\n");
    fprintf(fid,"Hp = 20*log10(abs(fftshift(fft(hp,  nfft))));\n");
    fprintf(fid,"G  = 20*log10(abs(fftshift(fft(g/k, nfft))));\n");

    fprintf(fid,"figure;\n");
    fprintf(fid,"plot(f,Hm, f,Hc, f,Hp, f,G,'-k','LineWidth',2, [-0.5/k 0.5/k],[-6.026 -6.026],'or');\n");
    fprintf(fid,"xlabel('Normalized Frequency');\n");
    fprintf(fid,"ylabel('Power Spectral Density');\n");
    fprintf(fid,"legend('transmit','channel','equalizer','composite','half-power points',1);\n");
    fprintf(fid,"axis([-0.5 0.5 -12 8]);\n");
    fprintf(fid,"grid on;\n");
    
    fclose(fid);
    printf("results written to '%s'\n", OUTPUT_FILENAME);

    return 0;
}
Exemplo n.º 12
0
int main(int argc, char*argv[])
{
    // options
    unsigned int num_symbols=500;   // number of symbols to observe
    float SNRdB = 30.0f;            // signal-to-noise ratio [dB]
    unsigned int hc_len=5;          // channel filter length
    unsigned int k=2;               // matched filter samples/symbol
    unsigned int m=3;               // matched filter delay (symbols)
    float beta=0.3f;                // matched filter excess bandwidth factor
    unsigned int p=3;               // equalizer length (symbols, gr_len = 2*k*p+1)
    float mu = 0.09f;               // LMS learning rate

    // modulation type/depth
    modulation_scheme ms = LIQUID_MODEM_QPSK;
    
    // plotting options
    unsigned int nfft = 512;    // fft size
    float gnuplot_version = 4.2;
    char filename_base[256] = "figures.gen/eqlms_cccf_blind";

    int dopt;
    while ((dopt = getopt(argc,argv,"hf:g:n:s:c:k:m:b:p:u:M:")) != EOF) {
        switch (dopt) {
        case 'h': usage();                      return 0;
        case 'f': strncpy(filename_base,optarg,256);    break;
        case 'g': gnuplot_version = atoi(optarg);       break;
        case 'n': num_symbols   = atoi(optarg); break;
        case 's': SNRdB         = atof(optarg); break;
        case 'c': hc_len        = atoi(optarg); break;
        case 'k': k             = atoi(optarg); break;
        case 'm': m             = atoi(optarg); break;
        case 'b': beta          = atof(optarg); break;
        case 'p': p             = atoi(optarg); break;
        case 'u': mu            = atof(optarg); break;
        case 'M':
            ms = liquid_getopt_str2mod(optarg);
            if (ms == LIQUID_MODEM_UNKNOWN) {
                fprintf(stderr,"error: %s, unknown/unsupported modulation scheme '%s'\n", argv[0], optarg);
                return 1;
            }
            break;
        default:
            exit(1);
        }
    }

    // validate input
    if (num_symbols == 0) {
        fprintf(stderr,"error: %s, number of symbols must be greater than zero\n", argv[0]);
        exit(1);
    } else if (hc_len == 0) {
        fprintf(stderr,"error: %s, channel must have at least 1 tap\n", argv[0]);
        exit(1);
    } else if (k < 2) {
        fprintf(stderr,"error: %s, samples/symbol must be at least 2\n", argv[0]);
        exit(1);
    } else if (m == 0) {
        fprintf(stderr,"error: %s, filter semi-length must be at least 1 symbol\n", argv[0]);
        exit(1);
    } else if (beta < 0.0f || beta > 1.0f) {
        fprintf(stderr,"error: %s, filter excess bandwidth must be in [0,1]\n", argv[0]);
        exit(1);
    } else if (p == 0) {
        fprintf(stderr,"error: %s, equalizer semi-length must be at least 1 symbol\n", argv[0]);
        exit(1);
    } else if (mu < 0.0f || mu > 1.0f) {
        fprintf(stderr,"error: %s, equalizer learning rate must be in [0,1]\n", argv[0]);
        exit(1);
    }

    // set 'random' seed on options
    srand( hc_len + p + nfft );

    // derived values
    unsigned int gt_len = 2*k*m+1;   // matched filter length
    unsigned int gr_len = 2*k*p+1;   // equalizer filter length
    unsigned int num_samples = k*num_symbols;

    // bookkeeping variables
    float complex sym_tx[num_symbols];  // transmitted data sequence
    float complex x[num_samples];       // interpolated time series
    float complex y[num_samples];       // channel output
    float complex z[num_samples];       // equalized output

    // least mean-squares (LMS) equalizer
    float mse[num_symbols];             // equalizer mean-squared error
    float complex gr[gr_len];           // equalizer filter coefficients

    unsigned int i;

    // generate matched filter response
    float gtf[gt_len];                   // matched filter response
    liquid_firdes_rnyquist(LIQUID_RNYQUIST_RRC, k, m, beta, 0.0f, gtf);
    
    // convert to complex coefficients
    float complex gt[gt_len];
    for (i=0; i<gt_len; i++)
        gt[i] = gtf[i]; //+ 0.1f*(randnf() + _Complex_I*randnf());

    // create interpolator
    interp_cccf interp = interp_cccf_create(k, gt, gt_len);

    // create the modem objects
    modem mod   = modem_create(ms);
    modem demod = modem_create(ms);
    unsigned int bps = modem_get_bps(mod);
    unsigned int M = 1 << bps;

    // generate channel impulse response, filter
#if 0
    float complex hc[hc_len];           // channel filter coefficients
    hc[0] = 1.0f;
    for (i=1; i<hc_len; i++)
        hc[i] = 0.09f*(randnf() + randnf()*_Complex_I);
#else
    // use fixed channel
    hc_len = 8;
    float complex hc[hc_len];           // channel filter coefficients
    hc[0] =   1.00000000+  0.00000000*_Complex_I;
    hc[1] =   0.08077553+ -0.00247592*_Complex_I;
    hc[2] =   0.03625883+ -0.09219734*_Complex_I;
    hc[3] =   0.05764082+  0.03277601*_Complex_I;
    hc[4] =  -0.04773349+ -0.18766306*_Complex_I;
    hc[5] =  -0.00101735+ -0.00270737*_Complex_I;
    hc[6] =  -0.05796884+ -0.12665297*_Complex_I;
    hc[7] =   0.03805391+ -0.07609370*_Complex_I;
#endif
    firfilt_cccf fchannel = firfilt_cccf_create(hc, hc_len);
    firfilt_cccf_print(fchannel);

    // generate random symbols
    for (i=0; i<num_symbols; i++)
        modem_modulate(mod, rand()%M, &sym_tx[i]);

    // interpolate
    for (i=0; i<num_symbols; i++)
        interp_cccf_execute(interp, sym_tx[i], &x[i*k]);
    
    // push through channel
    float nstd = powf(10.0f, -SNRdB/20.0f);
    for (i=0; i<num_samples; i++) {
        firfilt_cccf_push(fchannel, x[i]);
        firfilt_cccf_execute(fchannel, &y[i]);

        // add noise
        y[i] += nstd*(randnf() + randnf()*_Complex_I)*M_SQRT1_2;
    }

    // push through equalizers
    float grf[gr_len];
    liquid_firdes_rnyquist(LIQUID_RNYQUIST_RRC, k, p, beta, 0.0f, grf);
    for (i=0; i<gr_len; i++) {
        gr[i] = grf[i] / (float)k;
    }

    // create LMS equalizer
    eqlms_cccf eq = eqlms_cccf_create(gr, gr_len);
    eqlms_cccf_set_bw(eq, mu);

    // filtered error vector magnitude (emperical MSE)
    //float zeta=0.05f;   // smoothing factor (small zeta -> smooth MSE)

    float complex d_hat = 0.0f;
    unsigned int num_symbols_rx=0;
    for (i=0; i<num_samples; i++) {

        // push samples into equalizers
        eqlms_cccf_push(eq, y[i]);

        // compute outputs
        eqlms_cccf_execute(eq, &d_hat);

        // store outputs
        z[i] = d_hat;

        // check to see if buffer is full
        if ( i < gr_len) continue;

        // decimate by k
        if ( (i%k) != 0 ) continue;

        // estimate transmitted signal
        unsigned int sym_out;       // output symbol
        float complex d_prime;  // estimated input sample

        // LMS
        modem_demodulate(demod, d_hat, &sym_out);
        modem_get_demodulator_sample(demod, &d_prime);

        // update equalizers
        eqlms_cccf_step(eq, d_prime, d_hat);

#if 0
        // update filtered evm estimate
        float evm = crealf( (d_prime-d_hat)*conjf(d_prime-d_hat) );

        if (num_symbols_rx == 0) {
            mse[num_symbols_rx] = evm; 
        } else {
            mse[num_symbols_rx] = mse[num_symbols_rx-1]*(1-zeta) + evm*zeta;
        }
#else
        // compute ISI for entire system
        eqlms_cccf_get_weights(eq, gr);
        mse[num_symbols_rx] = eqlms_cccf_isi(k, gt, gt_len, hc, hc_len, gr, gr_len);
#endif

        // print filtered evm (emperical rms error)
        if ( ((num_symbols_rx+1)%100) == 0 )
            printf("%4u : mse = %12.8f dB\n",
                    num_symbols_rx+1,
                    20*log10f(mse[num_symbols_rx]));
        
        // increment output symbol counter
        num_symbols_rx++;
    }

    // get equalizer weights
    eqlms_cccf_get_weights(eq, gr);

    // destroy objects
    eqlms_cccf_destroy(eq);
    interp_cccf_destroy(interp);
    firfilt_cccf_destroy(fchannel);
    modem_destroy(mod);
    modem_destroy(demod);

    // 
    // export output
    //
    FILE * fid = NULL;
    char filename[300];

    // 
    // const: constellation
    //
    strncpy(filename, filename_base, 256);
    strcat(filename, "_const.gnu");
    fid = fopen(filename,"w");
    if (!fid) {
        fprintf(stderr,"error: %s, could not open file '%s' for writing\n", argv[0], filename);
        return 1;
    }
    fprintf(fid,"# %s: auto-generated file\n\n", filename);
    fprintf(fid,"reset\n");
    fprintf(fid,"set terminal postscript eps enhanced color solid rounded\n");
    fprintf(fid,"set size ratio 1\n");
    fprintf(fid,"set xrange [-1.5:1.5];\n");
    fprintf(fid,"set yrange [-1.5:1.5];\n");
    fprintf(fid,"set xlabel 'In-phase'\n");
    fprintf(fid,"set ylabel 'Quadrature phase'\n");
    fprintf(fid,"set grid xtics ytics\n");
    fprintf(fid,"set grid linetype 1 linecolor rgb '%s' linewidth 1\n",LIQUID_DOC_COLOR_GRID);
    fprintf(fid,"plot '-' using 1:2 with points pointtype 7 pointsize 0.5 linecolor rgb '%s' title 'first 50%%',\\\n", LIQUID_DOC_COLOR_GRAY);
    fprintf(fid,"     '-' using 1:2 with points pointtype 7 pointsize 0.7 linecolor rgb '%s' title 'last 50%%'\n",     LIQUID_DOC_COLOR_RED);
    // first half of symbols
    for (i=2*p; i<num_symbols/2; i+=k)
        fprintf(fid,"  %12.4e %12.4e\n", crealf(y[i]), cimagf(y[i]));
    fprintf(fid,"e\n");

    // second half of symbols
    for ( ; i<num_symbols; i+=k)
        fprintf(fid,"  %12.4e %12.4e\n", crealf(z[i]), cimagf(z[i]));
    fprintf(fid,"e\n");

    fclose(fid);
    printf("results written to '%s'\n", filename);

    // 
    // mse : mean-squared error
    //
    strncpy(filename, filename_base, 256);
    strcat(filename, "_mse.gnu");
    fid = fopen(filename,"w");
    if (!fid) {
        fprintf(stderr,"error: %s, could not open file '%s' for writing\n", argv[0], filename);
        return 1;
    }
    fprintf(fid,"# %s: auto-generated file\n\n", filename);
    fprintf(fid,"reset\n");
    fprintf(fid,"set terminal postscript eps enhanced color solid rounded\n");
    fprintf(fid,"set size ratio 0.3\n");
    fprintf(fid,"set xrange [0:%u];\n", num_symbols);
    fprintf(fid,"set yrange [1e-3:1e-1];\n");
    fprintf(fid,"set format y '10^{%%L}'\n");
    fprintf(fid,"set log y\n");
    fprintf(fid,"set xlabel 'symbol index'\n");
    fprintf(fid,"set ylabel 'mean-squared error'\n");
    fprintf(fid,"set grid xtics ytics\n");
    fprintf(fid,"set grid linetype 1 linecolor rgb '%s' linewidth 1\n",LIQUID_DOC_COLOR_GRID);
    fprintf(fid,"plot '-' using 1:2 with lines linewidth 4 linetype 1 linecolor rgb '%s' title 'LMS MSE'\n", LIQUID_DOC_COLOR_RED);
    // LMS
    for (i=0; i<num_symbols_rx; i++)
        fprintf(fid,"  %4u %16.8e\n", i, mse[i]);
    fprintf(fid,"e\n");

    fclose(fid);
    printf("results written to '%s'\n", filename);


    // 
    // psd : power spectral density
    //

    // scale transmit filter appropriately
    for (i=0; i<gt_len; i++) gt[i] /= (float)k;

    float complex Gt[nfft];     // transmit matched filter
    float complex Hc[nfft];     // channel response
    float complex Gr[nfft];     // equalizer response
    liquid_doc_compute_psdcf(gt, gt_len, Gt, nfft, LIQUID_DOC_PSDWINDOW_NONE, 0);
    liquid_doc_compute_psdcf(hc, hc_len, Hc, nfft, LIQUID_DOC_PSDWINDOW_NONE, 0);
    liquid_doc_compute_psdcf(gr, gr_len, Gr, nfft, LIQUID_DOC_PSDWINDOW_NONE, 0);
    fft_shift(Gt, nfft);
    fft_shift(Hc, nfft);
    fft_shift(Gr, nfft);
    float freq[nfft];
    for (i=0; i<nfft; i++)
        freq[i] = (float)(i) / (float)nfft - 0.5f;

    strncpy(filename, filename_base, 256);
    strcat(filename, "_freq.gnu");
    fid = fopen(filename,"w");
    if (!fid) {
        fprintf(stderr,"error: %s, could not open file '%s' for writing\n", argv[0], filename);
        return 1;
    }
    fprintf(fid,"# %s: auto-generated file\n\n", filename);
    fprintf(fid,"reset\n");
    fprintf(fid,"set terminal postscript eps enhanced color solid rounded\n");
    fprintf(fid,"set size ratio 0.6\n");
    fprintf(fid,"set xrange [-0.5:0.5];\n");
    fprintf(fid,"set yrange [-10:6]\n");
    fprintf(fid,"set xlabel 'Normalized Frequency'\n");
    fprintf(fid,"set ylabel 'Power Spectral Density [dB]'\n");
    fprintf(fid,"set key top right nobox\n");
    fprintf(fid,"set grid xtics ytics\n");
    fprintf(fid,"set grid linetype 1 linecolor rgb '%s' lw 1\n",LIQUID_DOC_COLOR_GRID);
    fprintf(fid,"plot '-' using 1:2 with lines linetype 1 linewidth 1.5 linecolor rgb '%s' title 'transmit',\\\n",  LIQUID_DOC_COLOR_GRAY);
    fprintf(fid,"     '-' using 1:2 with lines linetype 1 linewidth 1.5 linecolor rgb '%s' title 'channel',\\\n",   LIQUID_DOC_COLOR_RED);
    fprintf(fid,"     '-' using 1:2 with lines linetype 1 linewidth 1.5 linecolor rgb '%s' title 'equalizer',\\\n", LIQUID_DOC_COLOR_GREEN);
    fprintf(fid,"     '-' using 1:2 with lines linetype 1 linewidth 4.0 linecolor rgb '%s' title 'composite',\\\n", LIQUID_DOC_COLOR_BLUE);
    fprintf(fid,"     '-' using 1:2 with points pointtype 7 pointsize 0.6 linecolor rgb '%s' notitle\n", LIQUID_DOC_COLOR_BLUE);
    // received signal
    for (i=0; i<nfft; i++)
        fprintf(fid,"%12.8f %12.4e\n", freq[i], 20*log10f(cabsf(Gt[i])) );
    fprintf(fid,"e\n");

    // channel
    for (i=0; i<nfft; i++)
        fprintf(fid,"%12.8f %12.4e\n", freq[i], 20*log10f(cabsf(Hc[i])) );
    fprintf(fid,"e\n");

    // equalizer
    for (i=0; i<nfft; i++)
        fprintf(fid,"%12.8f %12.4e\n", freq[i], 20*log10f(cabsf(Gr[i])) );
    fprintf(fid,"e\n");

    // composite
    for (i=0; i<nfft; i++)
        fprintf(fid,"%12.8f %12.4e\n", freq[i], 20*log10f( cabsf(Gt[i])*cabsf(Hc[i])*cabsf(Gr[i])) );
    fprintf(fid,"e\n");

    // composite
    fprintf(fid,"%12.8f %12.4e\n", -0.5f/(float)k, 20*log10f(0.5f));
    fprintf(fid,"%12.8f %12.4e\n",  0.5f/(float)k, 20*log10f(0.5f));
    fprintf(fid,"e\n");

    fclose(fid);
    printf("results written to '%s'\n", filename);

    //
    // time...
    //
    strncpy(filename, filename_base, 256);
    strcat(filename, "_time.gnu");
    fid = fopen(filename,"w");
    if (!fid) {
        fprintf(stderr,"error: %s, could not open file '%s' for writing\n", argv[0], filename);
        return 1;
    }
    fprintf(fid,"# %s: auto-generated file\n\n", filename);
    fprintf(fid,"reset\n");
    fprintf(fid,"set terminal postscript eps enhanced color solid rounded\n");
    fprintf(fid,"set xrange [0:%u];\n",num_symbols);
    fprintf(fid,"set yrange [-1.5:1.5]\n");
    fprintf(fid,"set size ratio 0.3\n");
    fprintf(fid,"set xlabel 'Symbol Index'\n");
    fprintf(fid,"set key top right nobox\n");
    //fprintf(fid,"set ytics -5,1,5\n");
    fprintf(fid,"set grid xtics ytics\n");
    fprintf(fid,"set pointsize 0.6\n");
    fprintf(fid,"set grid linetype 1 linecolor rgb '%s' lw 1\n", LIQUID_DOC_COLOR_GRID);
    fprintf(fid,"set multiplot layout 2,1 scale 1.0,1.0\n");

    // real
    fprintf(fid,"# real\n");
    fprintf(fid,"set ylabel 'Real'\n");
    fprintf(fid,"plot '-' using 1:2 with lines linetype 1 linewidth 1 linecolor rgb '#999999' notitle,\\\n");
    fprintf(fid,"     '-' using 1:2 with points pointtype 7 linecolor rgb '%s' notitle'\n", LIQUID_DOC_COLOR_BLUE);
    // 
    for (i=0; i<num_samples; i++)
        fprintf(fid,"%12.8f %12.4e\n", (float)i/(float)k, crealf(z[i]));
    fprintf(fid,"e\n");
    // 
    for (i=0; i<num_samples; i+=k)
        fprintf(fid,"%12.8f %12.4e\n", (float)i/(float)k, crealf(z[i]));
    fprintf(fid,"e\n");

    // imag
    fprintf(fid,"# imag\n");
    fprintf(fid,"set ylabel 'Imag'\n");
    fprintf(fid,"plot '-' using 1:2 with lines linetype 1 linewidth 1 linecolor rgb '#999999' notitle,\\\n");
    fprintf(fid,"     '-' using 1:2 with points pointtype 7 linecolor rgb '%s' notitle'\n", LIQUID_DOC_COLOR_GREEN);
    // 
    for (i=0; i<num_samples; i++)
        fprintf(fid,"%12.8f %12.4e\n", (float)i/(float)k, cimagf(z[i]));
    fprintf(fid,"e\n");
    // 
    for (i=0; i<num_samples; i+=k)
        fprintf(fid,"%12.8f %12.4e\n", (float)i/(float)k, cimagf(z[i]));
    fprintf(fid,"e\n");

    fprintf(fid,"unset multiplot\n");

    // close output file
    fclose(fid);
    printf("results written to '%s'\n", filename);

    return 0;
}
Exemplo n.º 13
0
int main(int argc, char*argv[]) {
    srand( time(NULL) );

    // options
    int verbose = 1;                // verbose output flag
    float phi_max_abs = M_PI/4.0f;  // absolute maximum phase offset
    unsigned int num_phi = 21;      // number of phase steps
    unsigned int num_trials = 1000; // number of trials
    float SNRdB = 12.0f;            // signal-to-noise ratio [dB]
    modulation_scheme ms = LIQUID_MODEM_QPSK;
    char filename[256] = "";    // output filename

    int dopt;
    while ((dopt = getopt(argc,argv,"uhvqn:t:s:P:m:o:")) != EOF) {
        switch (dopt) {
        case 'u':
        case 'h':   usage();    return 0;
        case 'v':   verbose = 1;                    break;
        case 'q':   verbose = 0;                    break;
        case 'n':   num_phi = atoi(optarg);         break;
        case 't':   num_trials = atoi(optarg);      break;
        case 's':   SNRdB = atof(optarg);           break;
        case 'P':   phi_max_abs = atof(optarg);     break;
        case 'm':
            ms = liquid_getopt_str2mod(optarg);
            if (ms == LIQUID_MODEM_UNKNOWN) {
                fprintf(stderr,"error: %s, unknown/unsupported modulation scheme \"%s\"\n", argv[0], optarg);
                return 1;
            }
            break;
        case 'o':   strncpy(filename,optarg,255);   break;
        default:
            exit(1);
        }
    }

    // validate input
    if (phi_max_abs <= 0.0f) {
        fprintf(stderr,"error: %s, maximum absolute phase offset must be greater than 0\n", argv[0]);
        exit(1);
    } else if (num_phi < 3) {
        fprintf(stderr,"error: %s, number of phase steps must be at least 3\n", argv[0]);
        exit(1);
        fprintf(stderr,"error: %s, number of trials must be greater than 0\n", argv[0]);
        exit(1);
    }

    unsigned int bps = modulation_types[ms].bps;

    // generate filenames
    if ( strcmp(filename,"")==0 )
        sprintf(filename,"figures.gen/modem_phase_error_%s%u.dat", modulation_types[ms].name, 1<<bps);

    // derived values
    float phi_min = 0.0f; //phi_max_abs;
    float phi_max = phi_max_abs;
    float phi_step = (phi_max - phi_min) / (float)(num_phi-1);
    float nstd = powf(10.0f, -SNRdB/20.0f);

    // arrays
    float phi_hat_mean[num_phi];        // phase error estimate
    float phi_hat_mean_smooth[num_phi]; // phase error estimate (smoothed)

    // create modulator/demodulator
    modem mod = modem_create(ms);
    modem demod = modem_create(ms);
    unsigned int M = 1 << bps;

    //
    unsigned int i;
    unsigned int sym_in;
    unsigned int sym_out;
    unsigned int n=0;       // trials counter
    float complex x;
    float phi_hat;
    float phi=0.0f;
    for (i=0; i<num_phi; i++) {
        phi = phi_min + i*phi_step;

        phi_hat_mean[i] = 0.0f;

        // reset number of trials
        n = 0;

        do {
            for (sym_in=0; sym_in<M; sym_in++) {
                // modulate
                modem_modulate(mod, sym_in, &x);

                // channel (phase offset)
                x *= cexpf(_Complex_I*phi);
                x += nstd * (randnf() + _Complex_I*randnf()) * M_SQRT1_2;

                // demodulate
                modem_demodulate(demod, x, &sym_out);

                // get error
                phi_hat = modem_get_demodulator_phase_error(demod);

                // accumulate average
                phi_hat_mean[i] += phi_hat;
            }

            n += M;
        } while (n < num_trials);

        // scale by bps^2
        //phi_hat_mean[i] *= bps*bps;

        // normalize mean by number of trials
        phi_hat_mean[i] /= (float) (n);

        // print results
        if (verbose)
            printf("%6u / %6u : phi=%12.8f, phi-hat=%12.8f\n",
                    i+1, num_phi, phi, phi_hat_mean[i]);
    }

    // compute smoothed curve
    float phi_hat_tmp[num_phi];
    memmove(phi_hat_mean_smooth, phi_hat_mean, num_phi*sizeof(float));
    unsigned int j;
    for (j=0; j<5; j++) {
        memmove(phi_hat_tmp, phi_hat_mean_smooth, num_phi*sizeof(float));

        for (i=0; i<num_phi; i++) {
            if (i==0 || i == num_phi-1) {
                phi_hat_mean_smooth[i] = phi_hat_tmp[i];
            } else {
                phi_hat_mean_smooth[i] = 0.20f*phi_hat_tmp[i-1] +
                                         0.60f*phi_hat_tmp[i  ] +
                                         0.20f*phi_hat_tmp[i+1];
            }
        }
    }

    // destroy objects
    modem_destroy(mod);
    modem_destroy(demod);

    //
    // export output file
    //

    FILE * fid = fopen(filename,"w");
    if (!fid) {
        fprintf(stderr,"error: %s, cannot open '%s' for writing\n", argv[0], filename);
        exit(1);
    }
    fprintf(fid, "# %s : auto-generated file\n", filename);
    fprintf(fid, "# \n");

    // low SNR
    fprintf(fid, "# %12s %12s %12s\n", "phi", "phi-hat", "phi-hat-smooth");
    for (i=0; i<num_phi; i++) {
        phi = phi_min + i*phi_step;
        
        fprintf(fid,"  %12.8f %12.8f %12.8f\n", phi, phi_hat_mean[i], phi_hat_mean_smooth[i]);
    }

    fclose(fid);

    if (verbose)
        printf("results written to '%s'\n", filename);

    return 0;
}
Exemplo n.º 14
0
int main(int argc, char*argv[])
{
    // options
    unsigned int bps=6;         // bits per symbol
    unsigned int n=1024;        // number of data points to evaluate

    int dopt;
    while ((dopt = getopt(argc,argv,"uhp:")) != EOF) {
        switch (dopt) {
        case 'u':
        case 'h': usage(); return 0;
        case 'p': bps = atoi(optarg); break;
        default:
            exit(1);
        }
    }

    // validate input
    if (bps == 0) {
        fprintf(stderr,"error: %s, bits/symbol must be greater than zero\n", argv[0]);
        exit(1);
    }

    // derived values
    unsigned int i;
    unsigned int M = 1<<bps;    // constellation size

    // initialize constellation table
    float complex constellation[M];
    // initialize constellation (spiral)
    for (i=0; i<M; i++) {
        float r   = (float)i / logf((float)M) + 4.0f;
        float phi = (float)i / logf((float)M);
        constellation[i] = r * cexpf(_Complex_I*phi);
    }
    
    // create mod/demod objects
    modem mod   = modem_create_arbitrary(constellation, M);
    modem demod = modem_create_arbitrary(constellation, M);

    modem_print(mod);

    // run simulation
    float complex x[n];
    unsigned int num_errors = 0;

    // run simple BER simulation
    num_errors = 0;
    unsigned int sym_in;
    unsigned int sym_out;
    for (i=0; i<n; i++) {
        // generate and modulate random symbol
        sym_in = modem_gen_rand_sym(mod);
        modem_modulate(mod, sym_in, &x[i]);

        // add noise
        x[i] += 0.05 * randnf() * cexpf(_Complex_I*M_PI*randf());

        // demodulate
        modem_demodulate(demod, x[i], &sym_out);

        // accumulate errors
        num_errors += count_bit_errors(sym_in,sym_out);
    }
    printf("num bit errors: %4u / %4u\n", num_errors, bps*n);

    // destroy modem objects
    modem_destroy(mod);
    modem_destroy(demod);

    // 
    // export output file
    //
    FILE * fid = fopen(OUTPUT_FILENAME,"w");
    fprintf(fid,"%% %s : auto-generated file\n", OUTPUT_FILENAME);
    fprintf(fid,"clear all;\n");
    fprintf(fid,"close all;\n");
    fprintf(fid,"bps = %u;\n", bps);
    fprintf(fid,"M = %u;\n", M);

    for (i=0; i<n; i++) {
        fprintf(fid,"x(%3u) = %12.4e + j*%12.4e;\n", i+1,
                                                     crealf(x[i]),
                                                     cimagf(x[i]));
    }

    // plot results
    fprintf(fid,"figure;\n");
    fprintf(fid,"plot(x,'x','MarkerSize',1);\n");
    fprintf(fid,"xlabel('in-phase');\n");
    fprintf(fid,"ylabel('quadrature phase');\n");
    fprintf(fid,"title(['Arbitrary ' num2str(M) '-QAM']);\n");
    fprintf(fid,"axis([-1 1 -1 1]*1.9);\n");
    fprintf(fid,"axis square;\n");
    fprintf(fid,"grid on;\n");
    fclose(fid);

    printf("results written to '%s'\n", OUTPUT_FILENAME);
    printf("done.\n");

    return 0;
}