void SDRPostThread::initPFBChannelizer() {
// std::cout << "Initializing post-process FIR polyphase filterbank channelizer with " << numChannels << " channels." << std::endl;
if (channelizer) {
firpfbch_crcf_destroy(channelizer);
}
channelizer = firpfbch_crcf_create_kaiser(LIQUID_ANALYZER, numChannels, 4, 60);
chanBw = (sampleRate / numChannels);
chanCenters.resize(numChannels+1);
demodChannelActive.resize(numChannels+1);
// std::cout << "Channel bandwidth spacing: " << (chanBw) << std::endl;
}
int main() {
// options
unsigned int num_channels=8; // number of channels
unsigned int m=2; // filter delay
float As=-60; // stop-band attenuation
unsigned int num_frames=25; // number of frames
// create objects
firpfbch_crcf c = firpfbch_crcf_create_kaiser(LIQUID_ANALYZER, num_channels, m, As);
//firpfbch_crcf_print(c);
FILE*fid = fopen(OUTPUT_FILENAME,"w");
fprintf(fid,"%% %s: auto-generated file\n\n", OUTPUT_FILENAME);
fprintf(fid,"clear all;\nclose all;\n\n");
fprintf(fid,"num_channels=%u;\n", num_channels);
fprintf(fid,"num_frames=%u;\n", num_frames);
fprintf(fid,"x = zeros(1,%u);\n", num_channels * num_frames);
fprintf(fid,"y = zeros(%u,%u);\n", num_channels, num_frames);
unsigned int i, j, n=0;
float complex x[num_channels]; // time-domain input
float complex y[num_channels]; // channelized output
// create nco: sweeps entire range of frequencies over the evaluation interval
nco_crcf nco_tx = nco_crcf_create(LIQUID_VCO);
nco_crcf_set_frequency(nco_tx, 0.0f);
float df = 2*M_PI/(num_channels*num_frames);
printf("fr/ch:");
for (j=0; j<num_channels; j++) printf("%3u",j);
printf("\n");
for (i=0; i<num_frames; i++) {
// generate frame of data
for (j=0; j<num_channels; j++) {
nco_crcf_cexpf(nco_tx, &x[j]);
nco_crcf_adjust_frequency(nco_tx, df);
nco_crcf_step(nco_tx);
}
// execute analysis filter bank
firpfbch_crcf_analyzer_execute(c, x, y);
printf("%4u : ", i);
for (j=0; j<num_channels; j++) {
if (cabsf(y[j]) > num_channels / 4)
printf(" x ");
else
printf(" . ");
}
printf("\n");
// write output to file
for (j=0; j<num_channels; j++) {
// frequency data
fprintf(fid,"y(%4u,%4u) = %12.4e + j*%12.4e;\n", j+1, i+1, crealf(y[j]), cimagf(y[j]));
// time data
fprintf(fid,"x(%4u) = %12.4e + j*%12.4e;\n", n+1, crealf(x[j]), cimag(x[j]));
n++;
}
}
// destroy objects
nco_crcf_destroy(nco_tx);
firpfbch_crcf_destroy(c);
// plot results
fprintf(fid,"\n\n");
fprintf(fid,"figure;\n");
fprintf(fid,"subplot(2,1,1);\n");
fprintf(fid," plot(1:length(x),real(x),1:length(x),imag(x));\n");
fprintf(fid," xlabel('time');\n");
fprintf(fid," ylabel('signal');\n");
fprintf(fid,"subplot(2,1,2);\n");
fprintf(fid," plot(20*log10(abs(y.')/num_channels));\n");
fprintf(fid," xlabel('time (decimated)');\n");
fprintf(fid," ylabel('channelized energy [dB]');\n");
fprintf(fid,"n=min(num_channels,8);\n");
fprintf(fid,"figure;\n");
fprintf(fid,"for i=1:n\n");
fprintf(fid," subplot(n,1,i);\n");
fprintf(fid," plot(1:num_frames,real(y(i,:)),1:num_frames,imag(y(i,:)));\n");
fprintf(fid," axis off;\n");
fprintf(fid," ylabel(num2str(i));\n");
fprintf(fid,"end;\n");
fclose(fid);
printf("results written to %s\n", OUTPUT_FILENAME);
printf("done.\n");
return 0;
}
int main() {
// options
unsigned int num_channels = 16; // number of channels
unsigned int m = 5; // filter delay
float As = 60; // stop-band attenuation
unsigned int num_frames = 25; // number of frames
//
unsigned int i;
unsigned int k;
// derived values
unsigned int num_samples = num_frames * num_channels;
// data arrays
float complex x[num_channels][num_frames]; // channelized input
float complex y[num_samples]; // time-domain output [size: num_samples x 1]
// create narrow-band pulse
unsigned int pulse_len = 17; // pulse length [samples]
float bw = 0.30f; // pulse width (bandwidth)
float pulse[pulse_len]; // buffer
liquid_firdes_kaiser(pulse_len, bw, 50.0f, 0.0f, pulse);
// generate input signal(s)
int enabled[num_channels]; // signal enabled?
for (i=0; i<num_channels; i++) {
// pseudo-random channel enabled flag
enabled[i] = ((i*37)%101)%2;
if (enabled[i]) {
// move pulse to input buffer
for (k=0; k<num_frames; k++)
x[i][k] = k < pulse_len ? bw*pulse[k] : 0.0f;
} else {
// channel disabled; set as nearly zero (-100 dB impulse)
for (k=0; k<num_frames; k++)
x[i][k] = (k == 0) ? 1e-5f : 0.0f;
}
}
// create prototype filter
unsigned int h_len = 2*num_channels*m + 1;
float h[h_len];
liquid_firdes_kaiser(h_len, 0.5f/(float)num_channels, As, 0.0f, h);
#if 0
// create filterbank channelizer object using internal method for filter
firpfbch_crcf q = firpfbch_crcf_create_kaiser(LIQUID_SYNTHESIZER, num_channels, m, As);
#else
// create filterbank channelizer object using external filter coefficients
firpfbch_crcf q = firpfbch_crcf_create(LIQUID_SYNTHESIZER, num_channels, 2*m, h);
#endif
// channelize input data
float complex v[num_channels];
for (i=0; i<num_frames; i++) {
// assemble input vector
for (k=0; k<num_channels; k++)
v[k] = x[k][i];
// execute synthesis filter bank
firpfbch_crcf_synthesizer_execute(q, v, &y[i*num_channels]);
}
// destroy channelizer object
firpfbch_crcf_destroy(q);
//
// export results to file
//
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,"num_channels = %u;\n", num_channels);
fprintf(fid,"m = %u;\n", m);
fprintf(fid,"num_frames = %u;\n", num_frames);
fprintf(fid,"h_len = 2*num_channels*m+1;\n");
fprintf(fid,"num_samples = num_frames*num_channels;\n");
fprintf(fid,"h = zeros(1,h_len);\n");
fprintf(fid,"x = zeros(num_channels, num_frames);\n");
fprintf(fid,"y = zeros(1,num_samples);\n");
// save prototype filter
for (i=0; i<h_len; i++)
fprintf(fid," h(%6u) = %12.4e;\n", i+1, h[i]);
// save channelized input signals
for (i=0; i<num_frames; i++) {
for (k=0; k<num_channels; k++) {
float complex v = x[k][i];
fprintf(fid," x(%3u,%6u) = %12.4e + 1i*%12.4e;\n", k+1, i+1, crealf(v), cimagf(v));
}
}
// save output time signal
for (i=0; i<num_samples; i++)
fprintf(fid," y(%6u) = %12.4e + 1i*%12.4e;\n", i+1, crealf(y[i]), cimagf(y[i]));
// compute the PSD of each input and plot results on a square grid
fprintf(fid,"nfft = 1024;\n"); // TODO: use nextpow2
fprintf(fid,"f = [0:(nfft-1)]/nfft - 0.5;\n");
fprintf(fid,"n = ceil(sqrt(num_channels));\n");
fprintf(fid,"figure;\n");
fprintf(fid,"for i=1:num_channels,\n");
fprintf(fid," X = 20*log10(abs(fftshift(fft(x(i,:),nfft))));\n");
fprintf(fid," subplot(n,n,i);\n");
fprintf(fid," plot(f, X, 'Color', [0.25 0 0.25], 'LineWidth', 1.5);\n");
fprintf(fid," axis([-0.5 0.5 -120 20]);\n");
fprintf(fid," grid on;\n");
fprintf(fid," title(num2str(i-1));\n");
fprintf(fid,"end;\n");
// plot results
fprintf(fid,"\n");
fprintf(fid,"H = 20*log10(abs(fftshift(fft(h/num_channels,nfft))));\n");
fprintf(fid,"Y = 20*log10(abs(fftshift(fft(y/num_channels,nfft))));\n");
fprintf(fid,"figure;\n");
fprintf(fid,"subplot(2,1,1);\n");
fprintf(fid," plot(f, H, 'Color', [0 0.5 0.25], 'LineWidth', 2);\n");
fprintf(fid," axis([-0.5 0.5 -100 10]);\n");
fprintf(fid," grid on;\n");
fprintf(fid," xlabel('Normalized Frequency [f/F_s]');\n");
fprintf(fid," ylabel('Prototype Filter PSD');\n");
fprintf(fid,"subplot(2,1,2);\n");
fprintf(fid," plot(f, Y, 'Color', [0 0.25 0.5], 'LineWidth', 2);\n");
fprintf(fid," axis([-0.5 0.5 -100 0]);\n");
fprintf(fid," grid on;\n");
fprintf(fid," xlabel('Normalized Frequency [f/F_s]');\n");
fprintf(fid," ylabel('Output PSD');\n");
fclose(fid);
printf("results written to %s\n", OUTPUT_FILENAME);
printf("done.\n");
return 0;
}
int main() {
// options
unsigned int num_channels=4; // number of channels
unsigned int p=3; // filter length (symbols)
unsigned int num_symbols=6; // number of symbols
// derived values
unsigned int num_samples = num_channels * num_symbols;
unsigned int i;
unsigned int j;
// generate synthesis filter
// NOTE : these coefficients can be random; the purpose of this
// exercise is to demonstrate mathematical equivalence
unsigned int h_len = p*num_channels;
float h[h_len];
for (i=0; i<h_len; i++) h[i] = randnf();
// generate analysis filter
unsigned int g_len = p*num_channels;
float g[g_len];
for (i=0; i<g_len; i++)
g[i] = h[g_len-i-1];
// create synthesis/analysis filter objects
firfilt_crcf fs = firfilt_crcf_create(h, h_len);
firfilt_crcf fa = firfilt_crcf_create(g, g_len);
// create synthesis/analysis filterbank channelizer objects
firpfbch_crcf qs = firpfbch_crcf_create(LIQUID_SYNTHESIZER, num_channels, p, h);
firpfbch_crcf qa = firpfbch_crcf_create(LIQUID_ANALYZER, num_channels, p, g);
float complex x[num_samples]; // random input (noise)
float complex Y0[num_symbols][num_channels]; // channelized output (filterbank)
float complex Y1[num_symbols][num_channels]; // channelized output
float complex z0[num_samples]; // time-domain output (filterbank)
float complex z1[num_samples]; // time-domain output
// generate input sequence (complex noise)
for (i=0; i<num_samples; i++)
x[i] = randnf() * cexpf(_Complex_I*randf()*2*M_PI);
//
// ANALYZERS
//
//
// run analysis filter bank
//
for (i=0; i<num_symbols; i++)
firpfbch_crcf_analyzer_execute(qa, &x[i*num_channels], &Y0[i][0]);
//
// run traditional down-converter (inefficient)
//
float dphi; // carrier frequency
unsigned int n=0;
for (i=0; i<num_channels; i++) {
// reset filter
firfilt_crcf_clear(fa);
// set center frequency
dphi = 2.0f * M_PI * (float)i / (float)num_channels;
// reset symbol counter
n=0;
for (j=0; j<num_samples; j++) {
// push down-converted sample into filter
firfilt_crcf_push(fa, x[j]*cexpf(-_Complex_I*j*dphi));
// compute output at the appropriate sample time
assert(n<num_symbols);
if ( ((j+1)%num_channels)==0 ) {
firfilt_crcf_execute(fa, &Y1[n][i]);
n++;
}
}
assert(n==num_symbols);
}
//
// SYNTHESIZERS
//
//
// run synthesis filter bank
//
for (i=0; i<num_symbols; i++)
firpfbch_crcf_synthesizer_execute(qs, &Y0[i][0], &z0[i*num_channels]);
//
// run traditional up-converter (inefficient)
//
// clear output array
for (i=0; i<num_samples; i++)
z1[i] = 0.0f;
float complex y_hat;
for (i=0; i<num_channels; i++) {
// reset filter
firfilt_crcf_clear(fs);
// set center frequency
dphi = 2.0f * M_PI * (float)i / (float)num_channels;
// reset input symbol counter
n=0;
for (j=0; j<num_samples; j++) {
// interpolate sequence
if ( (j%num_channels)==0 ) {
assert(n<num_symbols);
firfilt_crcf_push(fs, Y1[n][i]);
n++;
} else {
firfilt_crcf_push(fs, 0);
}
firfilt_crcf_execute(fs, &y_hat);
// accumulate up-converted sample
z1[j] += y_hat * cexpf(_Complex_I*j*dphi);
}
assert(n==num_symbols);
}
// destroy objects
firfilt_crcf_destroy(fs);
firfilt_crcf_destroy(fa);
firpfbch_crcf_destroy(qs);
firpfbch_crcf_destroy(qa);
//
// RESULTS
//
//
// analyzers
//
// print filterbank channelizer
printf("\n");
printf("filterbank channelizer:\n");
for (i=0; i<num_symbols; i++) {
printf("%3u: ", i);
for (j=0; j<num_channels; j++) {
printf(" %8.5f+j%8.5f, ", crealf(Y0[i][j]), cimagf(Y0[i][j]));
}
printf("\n");
}
// print traditional channelizer
printf("\n");
printf("traditional channelizer:\n");
for (i=0; i<num_symbols; i++) {
printf("%3u: ", i);
for (j=0; j<num_channels; j++) {
printf(" %8.5f+j%8.5f, ", crealf(Y1[i][j]), cimagf(Y1[i][j]));
}
printf("\n");
}
float mse_analyzer[num_channels];
float complex d;
for (i=0; i<num_channels; i++) {
mse_analyzer[i] = 0.0f;
for (j=0; j<num_symbols; j++) {
d = Y0[j][i] - Y1[j][i];
mse_analyzer[i] += crealf(d*conjf(d));
}
mse_analyzer[i] /= num_symbols;
}
printf("\n");
printf("rmse: ");
for (i=0; i<num_channels; i++)
printf("%12.4e ", sqrt(mse_analyzer[i]));
printf("\n");
//
// synthesizers
//
printf("\n");
printf("output: filterbank: traditional:\n");
for (i=0; i<num_samples; i++) {
printf("%3u: %10.5f+%10.5fj %10.5f+%10.5fj\n",
i,
crealf(z0[i]), cimagf(z0[i]),
crealf(z1[i]), cimagf(z1[i]));
}
float mse_synthesizer = 0.0f;
for (i=0; i<num_samples; i++) {
d = z0[i] - z1[i];
mse_synthesizer += crealf(d*conjf(d));
}
mse_synthesizer /= num_samples;
printf("\n");
printf("rmse: %12.4e\n", sqrtf(mse_synthesizer));
//
// EXPORT DATA TO FILE
//
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,"num_channels=%u;\n", num_channels);
fprintf(fid,"num_symbols=%u;\n", num_symbols);
fprintf(fid,"num_samples = num_channels*num_symbols;\n");
fprintf(fid,"x = zeros(1,num_samples);\n");
fprintf(fid,"y0 = zeros(num_symbols,num_channels);\n");
fprintf(fid,"y1 = zeros(num_symbols,num_channels);\n");
fprintf(fid,"z0 = zeros(1,num_samples);\n");
fprintf(fid,"z1 = zeros(1,num_samples);\n");
// input
for (i=0; i<num_samples; i++)
fprintf(fid,"x(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(x[i]), cimag(x[i]));
// analysis
for (i=0; i<num_symbols; i++) {
for (j=0; j<num_channels; j++) {
fprintf(fid,"y0(%4u,%4u) = %12.4e + j*%12.4e;\n", i+1, j+1, crealf(Y0[i][j]), cimag(Y0[i][j]));
fprintf(fid,"y1(%4u,%4u) = %12.4e + j*%12.4e;\n", i+1, j+1, crealf(Y1[i][j]), cimag(Y1[i][j]));
}
}
// synthesis
for (i=0; i<num_samples; i++) {
fprintf(fid,"z0(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(z0[i]), cimag(z0[i]));
fprintf(fid,"z1(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(z1[i]), cimag(z1[i]));
}
fprintf(fid,"z0 = z0 / num_channels;\n");
fprintf(fid,"z1 = z1 / num_channels;\n");
// plot results
fprintf(fid,"\n\n");
fprintf(fid,"ts = 0:(num_symbols-1);\n");
fprintf(fid,"for i=1:num_channels,\n");
fprintf(fid,"figure;\n");
fprintf(fid,"title(['channel ' num2str(i)]);\n");
fprintf(fid,"subplot(2,1,1);\n");
fprintf(fid," plot(ts,real(y0(:,i)),'-x', ts,real(y1(:,i)),'s');\n");
//fprintf(fid," axis([0 (num_symbols-1) -2 2]);\n");
fprintf(fid,"subplot(2,1,2);\n");
fprintf(fid," plot(ts,imag(y0(:,i)),'-x', ts,imag(y1(:,i)),'s');\n");
//fprintf(fid," axis([0 (num_symbols-1) -2 2]);\n");
fprintf(fid,"end;\n");
fprintf(fid,"t = 0:(num_samples-1);\n");
fprintf(fid,"figure;\n");
fprintf(fid,"title('composite');\n");
fprintf(fid,"subplot(2,1,1);\n");
fprintf(fid," plot(t,real(z0),'-x', t,real(z1),'s');\n");
fprintf(fid,"subplot(2,1,2);\n");
fprintf(fid," plot(t,imag(z0),'-x', t,imag(z1),'s');\n");
fclose(fid);
printf("results written to '%s'\n", OUTPUT_FILENAME);
printf("done.\n");
return 0;
}
PfbSynthesizerComponent::~PfbSynthesizerComponent()
{
firpfbch_crcf_destroy(channelizer);
}
int main() {
// options
unsigned int num_channels=6; // must be even number
unsigned int num_symbols=32; // number of symbols
unsigned int m=3; // filter delay (symbols)
float beta = 0.9f; // filter excess bandwidth factor
int ftype = LIQUID_RNYQUIST_ARKAISER;
// number of frames (compensate for filter delay)
unsigned int num_frames = num_symbols + 2*m;
unsigned int num_samples = num_channels * num_frames;
// create synthesizer/analyzer objects
firpfbch_crcf cs0 = firpfbch_crcf_create_rnyquist(LIQUID_SYNTHESIZER, num_channels, m, beta, ftype);
firpfbch_crcf cs1 = firpfbch_crcf_create_rnyquist(LIQUID_SYNTHESIZER, num_channels, m, beta, ftype);
firpfbch_crcf ca0 = firpfbch_crcf_create_rnyquist(LIQUID_ANALYZER, num_channels, m, beta, ftype);
firpfbch_crcf ca1 = firpfbch_crcf_create_rnyquist(LIQUID_ANALYZER, num_channels, m, beta, ftype);
FILE*fid = fopen(OUTPUT_FILENAME,"w");
fprintf(fid,"%% %s: auto-generated file\n\n", OUTPUT_FILENAME);
fprintf(fid,"clear all;\nclose all;\n\n");
fprintf(fid,"num_channels=%u;\n", num_channels);
fprintf(fid,"num_symbols=%u;\n", num_symbols);
fprintf(fid,"num_samples=%u;\n", num_samples);
fprintf(fid,"X = zeros(%u,%u);\n", num_channels, num_frames);
fprintf(fid,"y = zeros(1,%u);\n", num_samples);
fprintf(fid,"Y = zeros(%u,%u);\n", num_channels, num_frames);
unsigned int i, j, n=0;
unsigned int k2 = num_channels/2;
float complex X[num_channels]; // channelized symbols
float complex y[num_channels]; // interpolated time-domain samples
float complex Y[num_channels]; // received symbols
// temporary buffers
float complex X0[num_channels];
float complex X1[num_channels];
float complex y0[num_channels];
float complex y1[num_channels];
float complex y1_prime[num_channels];
for (i=0; i<num_channels; i++) y1_prime[i] = 0.0f;
float complex Z0[num_channels];
float complex Z1[num_channels];
float complex z0[num_channels];
float complex z1[num_channels];
//float complex z0_prime[num_channels];
//float complex z1_prime[num_channels];
for (i=0; i<num_channels; i++) z0[i] = 0.0f;
for (i=0; i<num_channels; i++) z1[i] = 0.0f;
for (i=0; i<num_frames; i++) {
// generate frame data (random QPSK symbols)
for (j=0; j<num_channels; j++) {
X[j] = (rand()%2 ? 1.0f : -1.0f) +
(rand()%2 ? 1.0f : -1.0f)*_Complex_I;
}
// execute synthesyzer
//ofdmoqam_execute(cs, X, y);
for (j=0; j<num_channels; j+=2) {
// even channels
X0[j+0] = crealf(X[j+0]);
X1[j+0] = cimagf(X[j+0])*_Complex_I;
// odd channels
X0[j+1] = cimagf(X[j+1])*_Complex_I;
X1[j+1] = crealf(X[j+1]);
}
/*
for (j=0; j<num_channels; j++)
printf("X(%3u) = %12.8f + j*%12.8f\n", j, crealf(X[j]), cimagf(X[j]));
printf("\n");
for (j=0; j<num_channels; j++)
printf("X0(%3u) = %12.8f + j*%12.8f\n", j, crealf(X0[j]), cimagf(X0[j]));
printf("\n");
*/
firpfbch_crcf_synthesizer_execute(cs0, X0, y0);
firpfbch_crcf_synthesizer_execute(cs1, X1, y1);
// delay lower branch by half a symbol:
// copy first half of symbol from lower branch
memmove(&y1_prime[k2], &y1[0], k2*sizeof(float complex));
// add symbols
for (j=0; j<num_channels; j++)
y[j] = y0[j] + y1_prime[j];
// finish delay
// copy last half of symbol from lower branch
memmove(&y1_prime[0], &y1[k2], k2*sizeof(float complex));
// channel
// execute analyzer
//ofdmoqam_execute(ca, y, Y);
// delay lower branch by half a symbol
// copy first half of symbol to lower branch
memmove(&z1[k2], &y[0], k2*sizeof(float complex));
// run analyzer
firpfbch_crcf_analyzer_execute(ca0, z0, Z0);
firpfbch_crcf_analyzer_execute(ca1, z1, Z1);
// finish delay
// copy last half of symbol to lower branch
memmove(&z1[0], &y[k2], k2*sizeof(float complex));
// copy full symbol on upper branch
memmove(z0,y,num_channels*sizeof(float complex));
for (j=0; j<num_channels; j+=2) {
// even channels
Y[j+0] = crealf(Z0[j+0]) + cimagf(Z1[j+0])*_Complex_I;
// odd channels
Y[j+1] = cimagf(Z0[j+1])*_Complex_I + crealf(Z1[j+1]);
}
// write output to file
for (j=0; j<num_channels; j++) {
// frequency data
fprintf(fid,"X(%4u,%4u) = %12.4e + j*%12.4e;\n", j+1, i+1, crealf(X[j]), cimagf(X[j]));
// time data
fprintf(fid,"y(%4u) = %12.4e + j*%12.4e;\n", n+1, crealf(y[j]), cimag(y[j]));
// received data
fprintf(fid,"Y(%4u,%4u) = %12.4e + j*%12.4e;\n", j+1, i+1, crealf(Y[j]), cimagf(Y[j]));
n++;
}
}
// print results
fprintf(fid,"\n\n");
fprintf(fid,"s0 = 1:%u;\n", num_symbols);
fprintf(fid,"s1 = %u:%u;\n", 2*m+1, num_symbols + 2*m);
fprintf(fid,"Y = Y / num_channels; %% normalize by fft size\n");
fprintf(fid,"for i=1:min(6,num_channels),\n");
fprintf(fid," figure;\n");
fprintf(fid," subplot(2,1,1);\n");
fprintf(fid," plot(1:num_symbols,real(X(i,s0)),'-x',1:num_symbols,real(Y(i,s1)),'-x');\n");
fprintf(fid," ylabel('Re');\n");
fprintf(fid," title(['channel ' num2str(i-1)]);\n");
fprintf(fid," subplot(2,1,2);\n");
fprintf(fid," plot(1:num_symbols,imag(X(i,s0)),'-x',1:num_symbols,imag(Y(i,s1)),'-x');\n");
fprintf(fid," ylabel('Im');\n");
fprintf(fid," pause(0.2);\n");
fprintf(fid,"end;\n");
// plot time-domain output
fprintf(fid,"\n\n");
fprintf(fid,"t = 1:num_samples;\n");
fprintf(fid,"figure;\n");
fprintf(fid,"plot(t,real(y),'-', t,imag(y),'-');\n");
fprintf(fid,"xlabel('time');\n");
fprintf(fid,"ylabel('time series');\n");
fclose(fid);
printf("results written to %s\n", OUTPUT_FILENAME);
// destroy objects
firpfbch_crcf_destroy(cs0);
firpfbch_crcf_destroy(cs1);
firpfbch_crcf_destroy(ca0);
firpfbch_crcf_destroy(ca1);
printf("done.\n");
return 0;
}
int main() {
// options
unsigned int num_channels=8; // number of channels
unsigned int m=4; // filter delay
float As=60; // stop-band attenuation
unsigned int num_frames=25; // number of frames
//
unsigned int i;
unsigned int k;
// derived values
unsigned int num_samples = num_frames * num_channels;
// data arrays
float complex x[num_samples]; // time-domain input [size: num_samples x 1 ]
float complex y[num_samples]; // channelized output [size: num_channels x num_frames]
// initialize input with zeros
for (i=0; i<num_samples; i++)
x[i] = 0.0f;
// generate input signal(s)
unsigned int num_signals = 4;
float fc[4] = {0.0f, 0.25f, 0.375f, -0.375f}; // center frequencies
float bw[4] = {0.035f, 0.035f, 0.035f, 0.035f}; // bandwidths
unsigned int pulse_len = 137;
float pulse[pulse_len];
for (i=0; i<num_signals; i++) {
// create pulse
liquid_firdes_kaiser(pulse_len, bw[i], 50.0f, 0.0f, pulse);
// add pulse to input signal with carrier offset
for (k=0; k<pulse_len; k++)
x[k] += pulse[k] * cexpf(_Complex_I*2*M_PI*fc[i]*k) * bw[i];
}
// create prototype filter
unsigned int h_len = 2*num_channels*m + 1;
float h[h_len];
liquid_firdes_kaiser(h_len, 0.5f/(float)num_channels, As, 0.0f, h);
#if 0
// create filterbank channelizer object using internal method for filter
firpfbch_crcf q = firpfbch_crcf_create_kaiser(LIQUID_ANALYZER, num_channels, m, As);
#else
// create filterbank channelizer object using external filter coefficients
firpfbch_crcf q = firpfbch_crcf_create(LIQUID_ANALYZER, num_channels, 2*m, h);
#endif
// channelize input data
for (i=0; i<num_frames; i++) {
// execute analysis filter bank
firpfbch_crcf_analyzer_execute(q, &x[i*num_channels], &y[i*num_channels]);
}
// destroy channelizer object
firpfbch_crcf_destroy(q);
//
// export results to file
//
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,"num_channels = %u;\n", num_channels);
fprintf(fid,"m = %u;\n", m);
fprintf(fid,"num_frames = %u;\n", num_frames);
fprintf(fid,"h_len = 2*num_channels*m+1;\n");
fprintf(fid,"num_samples = num_frames*num_channels;\n");
fprintf(fid,"h = zeros(1,h_len);\n");
fprintf(fid,"x = zeros(1,num_samples);\n");
fprintf(fid,"y = zeros(num_channels, num_frames);\n");
// save prototype filter
for (i=0; i<h_len; i++)
fprintf(fid," h(%6u) = %12.4e;\n", i+1, h[i]);
// save input signal
for (i=0; i<num_samples; i++)
fprintf(fid," x(%6u) = %12.4e + 1i*%12.4e;\n", i+1, crealf(x[i]), cimagf(x[i]));
// save channelized output signals
for (i=0; i<num_frames; i++) {
for (k=0; k<num_channels; k++) {
float complex v = y[i*num_channels + k];
fprintf(fid," y(%3u,%6u) = %12.4e + 1i*%12.4e;\n", k+1, i+1, crealf(v), cimagf(v));
}
}
// plot results
fprintf(fid,"\n");
fprintf(fid,"nfft = 1024;\n"); // TODO: use nextpow2
fprintf(fid,"f = [0:(nfft-1)]/nfft - 0.5;\n");
fprintf(fid,"H = 20*log10(abs(fftshift(fft(h/num_channels,nfft))));\n");
fprintf(fid,"X = 20*log10(abs(fftshift(fft(x,nfft))));\n");
fprintf(fid,"figure;\n");
fprintf(fid,"subplot(2,1,1);\n");
fprintf(fid," plot(f, H, 'Color', [0 0.5 0.25], 'LineWidth', 2);\n");
fprintf(fid," axis([-0.5 0.5 -100 10]);\n");
fprintf(fid," grid on;\n");
fprintf(fid," xlabel('Normalized Frequency [f/F_s]');\n");
fprintf(fid," ylabel('Prototype Filter PSD');\n");
fprintf(fid,"subplot(2,1,2);\n");
fprintf(fid," plot(f, X, 'Color', [0 0.25 0.5], 'LineWidth', 2);\n");
fprintf(fid," axis([-0.5 0.5 -100 0]);\n");
fprintf(fid," grid on;\n");
fprintf(fid," xlabel('Normalized Frequency [f/F_s]');\n");
fprintf(fid," ylabel('Input PSD');\n");
// compute the PSD of each output and plot results on a square grid
fprintf(fid,"n = ceil(sqrt(num_channels));\n");
fprintf(fid,"figure;\n");
fprintf(fid,"for i=1:num_channels,\n");
fprintf(fid," Y = 20*log10(abs(fftshift(fft(y(i,:),nfft))));\n");
fprintf(fid," subplot(n,n,i);\n");
fprintf(fid," plot(f, Y, 'Color', [0.25 0 0.25], 'LineWidth', 1.5);\n");
fprintf(fid," axis([-0.5 0.5 -120 20]);\n");
fprintf(fid," grid on;\n");
fprintf(fid," title(num2str(i-1));\n");
fprintf(fid,"end;\n");
fclose(fid);
printf("results written to %s\n", OUTPUT_FILENAME);
printf("done.\n");
return 0;
}
//
// AUTOTEST: validate analysis correctness
//
void autotest_firpfbch_crcf_analysis()
{
float tol = 1e-4f; // error tolerance
unsigned int num_channels=4; // number of channels
unsigned int p=5; // filter length (symbols)
unsigned int num_symbols=12; // number of symbols
// derived values
unsigned int num_samples = num_channels * num_symbols;
unsigned int i;
unsigned int j;
// generate filter
// NOTE : these coefficients can be random; the purpose of this
// exercise is to demonstrate mathematical equivalence
unsigned int h_len = p*num_channels;
float h[h_len];
for (i=0; i<h_len; i++) h[i] = randnf();
// create filterbank object
firpfbch_crcf q = firpfbch_crcf_create(LIQUID_ANALYZER, num_channels, p, h);
// generate filter object
firfilt_crcf f = firfilt_crcf_create(h, h_len);
// allocate memory for arrays
float complex y[num_samples]; // time-domain input
float complex Y0[num_symbols][num_channels]; // channelized output
float complex Y1[num_symbols][num_channels]; // channelized output
// generate input sequence (complex noise)
for (i=0; i<num_samples; i++)
y[i] = randnf() * cexpf(_Complex_I*randf()*2*M_PI);
//
// run analysis filter bank
//
for (i=0; i<num_symbols; i++)
firpfbch_crcf_analyzer_execute(q, &y[i*num_channels], &Y0[i][0]);
//
// run traditional down-converter (inefficient)
//
float dphi; // carrier frequency
unsigned int n=0;
for (i=0; i<num_channels; i++) {
// reset filter
firfilt_crcf_clear(f);
// set center frequency
dphi = 2.0f * M_PI * (float)i / (float)num_channels;
// reset symbol counter
n=0;
for (j=0; j<num_samples; j++) {
// push down-converted sample into filter
firfilt_crcf_push(f, y[j]*cexpf(-_Complex_I*j*dphi));
// compute output at the appropriate sample time
assert(n<num_symbols);
if ( ((j+1)%num_channels)==0 ) {
firfilt_crcf_execute(f, &Y1[n][i]);
n++;
}
}
assert(n==num_symbols);
}
// destroy objects
firfilt_crcf_destroy(f);
firpfbch_crcf_destroy(q);
if (liquid_autotest_verbose) {
// print filterbank channelizer
printf("\n");
printf("filterbank channelizer:\n");
for (i=0; i<num_symbols; i++) {
printf("%3u: ", i);
for (j=0; j<num_channels; j++) {
printf(" %8.5f+j%8.5f, ", crealf(Y0[i][j]), cimagf(Y0[i][j]));
}
printf("\n");
}
// print traditional channelizer
printf("\n");
printf("traditional channelizer:\n");
for (i=0; i<num_symbols; i++) {
printf("%3u: ", i);
for (j=0; j<num_channels; j++) {
printf(" %8.5f+j%8.5f, ", crealf(Y1[i][j]), cimagf(Y1[i][j]));
}
printf("\n");
}
}
// compare results
for (i=0; i<num_symbols; i++) {
for (j=0; j<num_channels; j++) {
CONTEND_DELTA( crealf(Y0[i][j]), crealf(Y1[i][j]), tol );
CONTEND_DELTA( cimagf(Y0[i][j]), cimagf(Y1[i][j]), tol );
}
}
}