// Help function to keep code base small
// _kf : modulation factor
// _type : demodulation type {LIQUID_FREQDEM_DELAYCONJ, LIQUID_FREQDEM_PLL}
void freqmodem_test(float _kf,
liquid_freqdem_type _type)
{
// options
unsigned int num_samples = 1024;
//float tol = 1e-2f;
unsigned int i;
// create mod/demod objects
freqmod mod = freqmod_create(_kf); // modulator
freqdem dem = freqdem_create(_kf,_type); // demodulator
// allocate arrays
float m[num_samples]; // message signal
float complex r[num_samples]; // received signal (complex baseband)
float y[num_samples]; // demodulator output
// generate message signal (single-frequency sine)
for (i=0; i<num_samples; i++)
m[i] = 0.7f*cosf(2*M_PI*0.013f*i + 0.0f);
// modulate/demodulate signal
for (i=0; i<num_samples; i++) {
// modulate
freqmod_modulate(mod, m[i], &r[i]);
// demodulate
freqdem_demodulate(dem, r[i], &y[i]);
}
// delete modem objects
freqmod_destroy(mod);
freqdem_destroy(dem);
#if 0
// compute power spectral densities and compare
float complex mcf[num_samples];
float complex ycf[num_samples];
float complex M[num_samples];
float complex Y[num_samples];
for (i=0; i<num_samples; i++) {
mcf[i] = m[i] * hamming(i,num_samples);
ycf[i] = y[i] * hamming(i,num_samples);
}
fft_run(num_samples, mcf, M, LIQUID_FFT_FORWARD, 0);
fft_run(num_samples, ycf, Y, LIQUID_FFT_FORWARD, 0);
// run test: compare spectral magnitude
for (i=0; i<num_samples; i++)
CONTEND_DELTA( cabsf(Y[i]), cabsf(M[i]), tol );
#endif
}
// generate short sequence symbols
// _p : subcarrier allocation array
// _M : total number of subcarriers
// _S0 : output symbol (freq)
// _s0 : output symbol (time)
// _M_S0 : total number of enabled subcarriers in S0
void ofdmframe_init_S0(unsigned char * _p,
unsigned int _M,
float complex * _S0,
float complex * _s0,
unsigned int * _M_S0)
{
unsigned int i;
// compute m-sequence length
unsigned int m = liquid_nextpow2(_M);
if (m < 4) m = 4;
else if (m > 8) m = 8;
// generate m-sequence generator object
msequence ms = msequence_create_default(m);
unsigned int s;
unsigned int M_S0 = 0;
// short sequence
for (i=0; i<_M; i++) {
// generate symbol
//s = msequence_generate_symbol(ms,1);
s = msequence_generate_symbol(ms,3) & 0x01;
if (_p[i] == OFDMFRAME_SCTYPE_NULL) {
// NULL subcarrier
_S0[i] = 0.0f;
} else {
if ( (i%2) == 0 ) {
// even subcarrer
_S0[i] = s ? 1.0f : -1.0f;
M_S0++;
} else {
// odd subcarrer (ignore)
_S0[i] = 0.0f;
}
}
}
// destroy objects
msequence_destroy(ms);
// ensure at least one subcarrier was enabled
if (M_S0 == 0) {
fprintf(stderr,"error: ofdmframe_init_S0(), no subcarriers enabled; check allocation\n");
exit(1);
}
// set return value(s)
*_M_S0 = M_S0;
// run inverse fft to get time-domain sequence
fft_run(_M, _S0, _s0, FFT_REVERSE, 0);
// normalize time-domain sequence level
float g = 1.0f / sqrtf(M_S0);
for (i=0; i<_M; i++)
_s0[i] *= g;
}
// generate long sequence symbols
// _p : subcarrier allocation array
// _M : total number of subcarriers
// _S1 : output symbol (freq)
// _s1 : output symbol (time)
// _M_S1 : total number of enabled subcarriers in S1
void ofdmframe_init_S1(unsigned char * _p,
unsigned int _M,
float complex * _S1,
float complex * _s1,
unsigned int * _M_S1)
{
unsigned int i;
// compute m-sequence length
unsigned int m = liquid_nextpow2(_M);
if (m < 4) m = 4;
else if (m > 8) m = 8;
// increase m such that the resulting S1 sequence will
// differ significantly from S0 with the same subcarrier
// allocation array
m++;
// generate m-sequence generator object
msequence ms = msequence_create_default(m);
unsigned int s;
unsigned int M_S1 = 0;
// long sequence
for (i=0; i<_M; i++) {
// generate symbol
//s = msequence_generate_symbol(ms,1);
s = msequence_generate_symbol(ms,3) & 0x01;
if (_p[i] == OFDMFRAME_SCTYPE_NULL) {
// NULL subcarrier
_S1[i] = 0.0f;
} else {
_S1[i] = s ? 1.0f : -1.0f;
M_S1++;
}
}
// destroy objects
msequence_destroy(ms);
// ensure at least one subcarrier was enabled
if (M_S1 == 0) {
fprintf(stderr,"error: ofdmframe_init_S1(), no subcarriers enabled; check allocation\n");
exit(1);
}
// set return value(s)
*_M_S1 = M_S1;
// run inverse fft to get time-domain sequence
fft_run(_M, _S1, _s1, FFT_REVERSE, 0);
// normalize time-domain sequence level
float g = 1.0f / sqrtf(M_S1);
for (i=0; i<_M; i++)
_s1[i] *= g;
}
// Design flipped Nyquist/root-Nyquist filter
// _type : filter type (e.g. LIQUID_NYQUIST_FEXP)
// _root : square-root Nyquist filter?
// _k : samples/symbol
// _m : symbol delay
// _beta : rolloff factor (0 < beta <= 1)
// _dt : fractional sample delay
// _h : output coefficient buffer (length: 2*k*m+1)
void liquid_firdes_fnyquist(liquid_nyquist_type _type,
int _root,
unsigned int _k,
unsigned int _m,
float _beta,
float _dt,
float * _h)
{
// validate input
if ( _k < 1 ) {
fprintf(stderr,"error: liquid_firdes_fnyquist(): k must be greater than 0\n");
exit(1);
} else if ( _m < 1 ) {
fprintf(stderr,"error: liquid_firdes_fnyquist(): m must be greater than 0\n");
exit(1);
} else if ( (_beta < 0.0f) || (_beta > 1.0f) ) {
fprintf(stderr,"error: liquid_firdes_fnyquist(): beta must be in [0,1]\n");
exit(1);
} else;
unsigned int i;
// derived values
unsigned int h_len = 2*_k*_m+1; // filter length
float H_prime[h_len]; // frequency response of Nyquist filter (real)
float complex H[h_len]; // frequency response of Nyquist filter
float complex h[h_len]; // impulse response of Nyquist filter
// compute Nyquist filter frequency response
switch (_type) {
case LIQUID_NYQUIST_FEXP:
liquid_firdes_fexp_freqresponse(_k, _m, _beta, H_prime);
break;
case LIQUID_NYQUIST_FSECH:
liquid_firdes_fsech_freqresponse(_k, _m, _beta, H_prime);
break;
case LIQUID_NYQUIST_FARCSECH:
liquid_firdes_farcsech_freqresponse(_k, _m, _beta, H_prime);
break;
default:
fprintf(stderr,"error: liquid_firdes_fnyquist(), unknown/unsupported filter type\n");
exit(1);
}
// copy result to fft input buffer, computing square root
// if required
for (i=0; i<h_len; i++)
H[i] = _root ? sqrtf(H_prime[i]) : H_prime[i];
// compute ifft
fft_run(h_len, H, h, FFT_REVERSE, 0);
// copy shifted, scaled response
for (i=0; i<h_len; i++)
_h[i] = crealf( h[(i+_k*_m+1)%h_len] ) * (float)_k / (float)(h_len);
}
/*
* Filter with fast convolution (overlap-add algorithm).
*/
gint fftfilt_run(struct fftfilt *s, complex in, complex **out)
{
gint i;
/* collect filterlen/2 input samples */
s->fft->in[s->inptr++] = in;
if (s->inptr < s->filterlen / 2)
return 0;
/* FFT */
fft_run(s->fft);
/* multiply with the filter shape */
for (i = 0; i < s->filterlen; i++)
s->ift->in[i] = cmul(s->fft->out[i], s->filter[i]);
/* IFFT */
fft_run(s->ift);
/* overlap and add */
for (i = 0; i < s->filterlen / 2; i++) {
c_re(s->ift->out[i]) += c_re(s->ovlbuf[i]);
c_im(s->ift->out[i]) += c_im(s->ovlbuf[i]);
}
*out = s->ift->out;
/* save the second half for overlapping */
for (i = 0; i < s->filterlen / 2; i++) {
c_re(s->ovlbuf[i]) = c_re(s->ift->out[i + s->filterlen / 2]);
c_im(s->ovlbuf[i]) = c_im(s->ift->out[i + s->filterlen / 2]);
}
/* clear inbuf */
fft_clear_inbuf(s->fft);
s->inptr = 0;
/* signal the caller there is filterlen/2 samples ready */
return s->filterlen / 2;
}
void fftfilt_set_freqs(struct fftfilt *s, gdouble f1, gdouble f2)
{
gint len = s->filterlen / 2 + 1;
gdouble t, h, x;
gint i;
fft_clear_inbuf(s->tmpfft);
for (i = 0; i < len; i++) {
t = i - (len - 1.0) / 2.0;
h = i / (len - 1.0);
x = (2 * f2 * sinc(2 * f2 * t) -
2 * f1 * sinc(2 * f1 * t)) * hamming(h);
c_re(s->tmpfft->in[i]) = x;
c_im(s->tmpfft->in[i]) = 0.0;
#ifdef DEBUG
fprintf(stderr, "% e\t", x);
#endif
}
fft_run(s->tmpfft);
/*
* Scale down by 'filterlen' because inverse transform is
* unscaled in FFTW.
*/
for (i = 0; i < s->filterlen; i++) {
c_re(s->filter[i]) = c_re(s->tmpfft->out[i]) / s->filterlen;
c_im(s->filter[i]) = c_im(s->tmpfft->out[i]) / s->filterlen;
}
#ifdef DEBUG
for (i = 0; i < s->filterlen; i++)
fprintf(stderr, "% e\n", 10 * log10(cpwr(s->filter[i])));
#endif
}
//
// AUTOTEST : test multi-stage arbitrary resampler
//
void autotest_msresamp_crcf()
{
// options
unsigned int m = 13; // filter semi-length (filter delay)
float r=0.127115323f; // resampling rate (output/input)
float As=60.0f; // resampling filter stop-band attenuation [dB]
unsigned int n=1200; // number of input samples
float fx=0.0254230646f; // complex input sinusoid frequency (0.2*r)
//float bw=0.45f; // resampling filter bandwidth
//unsigned int npfb=64; // number of filters in bank (timing resolution)
unsigned int i;
// number of input samples (zero-padded)
unsigned int nx = n + m;
// output buffer with extra padding for good measure
unsigned int y_len = (unsigned int) ceilf(1.1 * nx * r) + 4;
// arrays
float complex x[nx];
float complex y[y_len];
// create resampler
msresamp_crcf q = msresamp_crcf_create(r,As);
// generate input signal
float wsum = 0.0f;
for (i=0; i<nx; i++) {
// compute window
float w = i < n ? kaiser(i, n, 10.0f, 0.0f) : 0.0f;
// apply window to complex sinusoid
x[i] = cexpf(_Complex_I*2*M_PI*fx*i) * w;
// accumulate window
wsum += w;
}
// resample
unsigned int ny=0;
unsigned int nw;
for (i=0; i<nx; i++) {
// execute resampler, storing in output buffer
msresamp_crcf_execute(q, &x[i], 1, &y[ny], &nw);
// increment output size
ny += nw;
}
// clean up allocated objects
msresamp_crcf_destroy(q);
//
// analyze resulting signal
//
// check that the actual resampling rate is close to the target
float r_actual = (float)ny / (float)nx;
float fy = fx / r; // expected output frequency
// run FFT and ensure that carrier has moved and that image
// frequencies and distortion have been adequately suppressed
unsigned int nfft = 1 << liquid_nextpow2(ny);
float complex yfft[nfft]; // fft input
float complex Yfft[nfft]; // fft output
for (i=0; i<nfft; i++)
yfft[i] = i < ny ? y[i] : 0.0f;
fft_run(nfft, yfft, Yfft, LIQUID_FFT_FORWARD, 0);
fft_shift(Yfft, nfft); // run FFT shift
// find peak frequency
float Ypeak = 0.0f;
float fpeak = 0.0f;
float max_sidelobe = -1e9f; // maximum side-lobe [dB]
float main_lobe_width = 0.07f; // TODO: figure this out from Kaiser's equations
for (i=0; i<nfft; i++) {
// normalized output frequency
float f = (float)i/(float)nfft - 0.5f;
// scale FFT output appropriately
Yfft[i] /= (r * wsum);
float Ymag = 20*log10f( cabsf(Yfft[i]) );
// find frequency location of maximum magnitude
if (Ymag > Ypeak || i==0) {
Ypeak = Ymag;
fpeak = f;
}
// find peak side-lobe value, ignoring frequencies
// within a certain range of signal frequency
if ( fabsf(f-fy) > main_lobe_width )
max_sidelobe = Ymag > max_sidelobe ? Ymag : max_sidelobe;
}
if (liquid_autotest_verbose) {
// print results
printf(" desired resampling rate : %12.8f\n", r);
printf(" measured resampling rate : %12.8f (%u/%u)\n", r_actual, ny, nx);
printf(" peak spectrum : %12.8f dB (expected 0.0 dB)\n", Ypeak);
printf(" peak frequency : %12.8f (expected %-12.8f)\n", fpeak, fy);
printf(" max sidelobe : %12.8f dB (expected at least %.2f dB)\n", max_sidelobe, -As);
}
CONTEND_DELTA( r_actual, r, 0.01f ); // check actual output sample rate
CONTEND_DELTA( Ypeak, 0.0f, 0.25f ); // peak should be about 0 dB
CONTEND_DELTA( fpeak, fy, 0.01f ); // peak frequency should be nearly 0.2
CONTEND_LESS_THAN( max_sidelobe, -As ); // maximum side-lobe should be sufficiently low
#if 0
// export results for debugging
char filename[] = "msresamp_crcf_autotest.m";
FILE*fid = fopen(filename,"w");
fprintf(fid,"%% %s: auto-generated file\n",filename);
fprintf(fid,"clear all;\n");
fprintf(fid,"close all;\n");
fprintf(fid,"r = %12.8f;\n", r);
fprintf(fid,"nx = %u;\n", nx);
fprintf(fid,"ny = %u;\n", ny);
fprintf(fid,"nfft = %u;\n", nfft);
fprintf(fid,"Y = zeros(1,nfft);\n");
for (i=0; i<nfft; i++)
fprintf(fid,"Y(%3u) = %12.4e + j*%12.4e;\n", i+1, crealf(Yfft[i]), cimagf(Yfft[i]));
fprintf(fid,"\n\n");
fprintf(fid,"%% plot frequency-domain result\n");
fprintf(fid,"f=[0:(nfft-1)]/nfft-0.5;\n");
fprintf(fid,"figure;\n");
fprintf(fid,"plot(f,20*log10(abs(Y)),'Color',[0.25 0.5 0.0],'LineWidth',2);\n");
fprintf(fid,"grid on;\n");
fprintf(fid,"xlabel('normalized frequency');\n");
fprintf(fid,"ylabel('PSD [dB]');\n");
fprintf(fid,"axis([-0.5 0.5 -120 20]);\n");
fclose(fid);
printf("results written to %s\n",filename);
#endif
}
int main(int argc, char*argv[]) {
// options
unsigned int k=4; // filter samples/symbol
unsigned int m=3; // filter delay [symbols]
float beta = 0.3f; // filter excess bandwidth factor
// read properties from command line
int dopt;
while ((dopt = getopt(argc,argv,"uhk:m:b:")) != EOF) {
switch (dopt) {
case 'u':
case 'h': usage(); return 0;
case 'k': k = atoi(optarg); break;
case 'm': m = atoi(optarg); break;
case 'b': beta = atof(optarg); break;
default:
exit(1);
}
}
// validate input
if (k < 2) {
fprintf(stderr,"error: %s, k must be at least 2\n", argv[0]);
exit(1);
} else if (m < 1) {
fprintf(stderr,"error: %s, m must be at least 1\n", argv[0]);
exit(1);
} else if (beta <= 0.0f || beta >= 1.0f) {
fprintf(stderr,"error: %s, beta must be in (0,1)\n", argv[0]);
exit(1);
}
unsigned int i;
// derived values
unsigned int h_len = 2*k*m+1; // filter length
// arrays
float ht[h_len]; // transmit filter coefficients
float hr[h_len]; // recieve filter coefficients
//
// start of filter design procedure
//
float H_prime[h_len]; // frequency response of Nyquist filter
float complex h_tx[h_len]; // impulse response of square-root Nyquist filter
float complex H_tx[h_len]; // frequency response of square-root Nyquist filter
// compute frequency response of Nyquist filter
for (i=0; i<h_len; i++) {
float f = (float)i / (float)h_len;
if (f > 0.5f) f = f - 1.0f;
H_prime[i] = firdes_freqresponse_fexp(f,k,beta);
}
// compute square-root response, copy to fft input
for (i=0; i<h_len; i++)
H_tx[i] = sqrtf(H_prime[i]);
// compute ifft and copy response
fft_run(h_len, H_tx, h_tx, LIQUID_FFT_BACKWARD, 0);
for (i=0; i<h_len; i++)
ht[i] = crealf( h_tx[(i+k*m+1)%h_len] ) / (float)(h_len);
// copy receive...
for (i=0; i<h_len; i++)
hr[i] = ht[i];
#if 0
// print results
for (i=0; i<h_len; i++)
printf("H_prime(%3u) = %12.8f;\n", i+1, H_prime[i]);
#endif
//
// end of filter design procedure
//
// print results to screen
printf("fexp receive filter:\n");
for (i=0; i<h_len; i++)
printf(" hr(%3u) = %12.8f;\n", i+1, hr[i]);
// compute isi
float rxy0 = liquid_filter_crosscorr(ht,h_len, hr,h_len, 0);
float isi_rms = 0.0f;
for (i=1; i<2*m; i++) {
float e = liquid_filter_crosscorr(ht,h_len, hr,h_len, i*k) / rxy0;
isi_rms += e*e;
}
isi_rms = sqrtf(isi_rms / (float)(2*m-1));
printf("\n");
printf("ISI (RMS) = %12.8f dB\n", 20*log10f(isi_rms));
//
// 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,"\n\n");
fprintf(fid,"k = %u;\n", k);
fprintf(fid,"m = %u;\n", m);
fprintf(fid,"beta = %f;\n", beta);
fprintf(fid,"h_len = 2*k*m+1;\n");
fprintf(fid,"nfft = 1024;\n");
fprintf(fid,"ht = zeros(1,h_len);\n");
fprintf(fid,"hp = zeros(1,h_len);\n");
fprintf(fid,"hr = zeros(1,h_len);\n");
// print results
for (i=0; i<h_len; i++) fprintf(fid,"ht(%3u) = %12.4e;\n", i+1, ht[i]);
for (i=0; i<h_len; i++) fprintf(fid,"hr(%3u) = %12.4e;\n", i+1, hr[i]);
fprintf(fid,"hc = k*conv(ht,hr);\n");
// plot results
fprintf(fid,"f = [0:(nfft-1)]/nfft - 0.5;\n");
fprintf(fid,"Ht = 20*log10(abs(fftshift(fft(ht, nfft))));\n");
fprintf(fid,"Hr = 20*log10(abs(fftshift(fft(hr, nfft))));\n");
fprintf(fid,"Hc = 20*log10(abs(fftshift(fft(hc/k,nfft))));\n");
fprintf(fid,"\n");
fprintf(fid,"figure;\n");
fprintf(fid,"plot(f,Ht,'LineWidth',1,'Color',[0.00 0.25 0.50],...\n");
fprintf(fid," f,Hr,'LineWidth',1,'Color',[0.00 0.50 0.25],...\n");
fprintf(fid," f,Hc,'LineWidth',2,'Color',[0.50 0.00 0.00],...\n");
fprintf(fid," [-0.5/k 0.5/k], [1 1]*20*log10(0.5),'or');\n");
fprintf(fid,"legend('transmit','receive','composite','alias points',1);\n");
fprintf(fid,"xlabel('Normalized Frequency');\n");
fprintf(fid,"ylabel('PSD');\n");
fprintf(fid,"grid on;\n");
fprintf(fid,"axis([-0.5 0.5 -100 20]);\n");
fprintf(fid,"\n");
fprintf(fid,"figure;\n");
fprintf(fid,"tr = [ -k*m:k*m]/k;\n");
fprintf(fid,"tc = [-2*k*m:2*k*m]/k;\n");
fprintf(fid,"ic = [0:k:(4*k*m)]+1;\n");
fprintf(fid,"subplot(2,1,1);\n");
fprintf(fid," plot(tr,ht,'-x', tr,hr,'-x');\n");
fprintf(fid," legend('transmit','receive',1);\n");
fprintf(fid," xlabel('Time');\n");
fprintf(fid," ylabel('fexp Tx/Rx Filters');\n");
fprintf(fid," grid on;\n");
fprintf(fid," axis([-2*m 2*m floor(5*min([hr ht]))/5 ceil(5*max([hr ht]))/5]);\n");
fprintf(fid,"subplot(2,1,2);\n");
fprintf(fid," plot(tc,hc,'-x', tc(ic),hc(ic),'or');\n");
fprintf(fid," xlabel('Time');\n");
fprintf(fid," ylabel('fexp Composite Response');\n");
fprintf(fid," grid on;\n");
fprintf(fid," axis([-2*m 2*m -0.2 1.2]);\n");
fprintf(fid," axis([-2*m 2*m floor(5*min(hc))/5 ceil(5*max(hc))/5]);\n");
fclose(fid);
printf("results written to %s.\n", OUTPUT_FILENAME);
return 0;
}
int main(int argc, char*argv[])
{
// options
float r = 1.1f; // resampling rate (output/input)
unsigned int m = 13; // resampling filter semi-length (filter delay)
float As = 60.0f; // resampling filter stop-band attenuation [dB]
float bw = 0.45f; // resampling filter bandwidth
unsigned int npfb = 64; // number of filters in bank (timing resolution)
unsigned int n = 400; // number of input samples
float fc = 0.044f; // complex sinusoid frequency
int dopt;
while ((dopt = getopt(argc,argv,"hr:m:b:s:p:n:f:")) != EOF) {
switch (dopt) {
case 'h': usage(); return 0;
case 'r': r = atof(optarg); break;
case 'm': m = atoi(optarg); break;
case 'b': bw = atof(optarg); break;
case 's': As = atof(optarg); break;
case 'p': npfb = atoi(optarg); break;
case 'n': n = atoi(optarg); break;
case 'f': fc = atof(optarg); break;
default:
exit(1);
}
}
// validate input
if (r <= 0.0f) {
fprintf(stderr,"error: %s, resampling rate must be greater than zero\n", argv[0]);
exit(1);
} else if (m == 0) {
fprintf(stderr,"error: %s, filter semi-length must be greater than zero\n", argv[0]);
exit(1);
} else if (bw == 0.0f || bw >= 0.5f) {
fprintf(stderr,"error: %s, filter bandwidth must be in (0,0.5)\n", argv[0]);
exit(1);
} else if (As < 0.0f) {
fprintf(stderr,"error: %s, filter stop-band attenuation must be greater than zero\n", argv[0]);
exit(1);
} else if (npfb == 0) {
fprintf(stderr,"error: %s, filter bank size must be greater than zero\n", argv[0]);
exit(1);
} else if (n == 0) {
fprintf(stderr,"error: %s, number of input samples must be greater than zero\n", argv[0]);
exit(1);
}
unsigned int i;
// number of input samples (zero-padded)
unsigned int nx = n + m;
// output buffer with extra padding for good measure
unsigned int y_len = (unsigned int) ceilf(1.1 * nx * r) + 4;
// arrays
float complex x[nx];
float complex y[y_len];
// create resampler
resamp_crcf q = resamp_crcf_create(r,m,bw,As,npfb);
// generate input signal
float wsum = 0.0f;
for (i=0; i<nx; i++) {
// compute window
float w = i < n ? kaiser(i, n, 10.0f, 0.0f) : 0.0f;
// apply window to complex sinusoid
x[i] = cexpf(_Complex_I*2*M_PI*fc*i) * w;
// accumulate window
wsum += w;
}
// resample
unsigned int ny=0;
#if 0
// execute one sample at a time
unsigned int nw;
for (i=0; i<nx; i++) {
// execute resampler, storing in output buffer
resamp_crcf_execute(q, x[i], &y[ny], &nw);
// increment output size
ny += nw;
}
#else
// execute on block of samples
resamp_crcf_execute_block(q, x, nx, y, &ny);
#endif
// clean up allocated objects
resamp_crcf_destroy(q);
//
// analyze resulting signal
//
// check that the actual resampling rate is close to the target
float r_actual = (float)ny / (float)nx;
float fy = fc / r; // expected output frequency
// run FFT and ensure that carrier has moved and that image
// frequencies and distortion have been adequately suppressed
unsigned int nfft = 1 << liquid_nextpow2(ny);
float complex yfft[nfft]; // fft input
float complex Yfft[nfft]; // fft output
for (i=0; i<nfft; i++)
yfft[i] = i < ny ? y[i] : 0.0f;
fft_run(nfft, yfft, Yfft, LIQUID_FFT_FORWARD, 0);
fft_shift(Yfft, nfft); // run FFT shift
// find peak frequency
float Ypeak = 0.0f;
float fpeak = 0.0f;
float max_sidelobe = -1e9f; // maximum side-lobe [dB]
float main_lobe_width = 0.07f; // TODO: figure this out from Kaiser's equations
for (i=0; i<nfft; i++) {
// normalized output frequency
float f = (float)i/(float)nfft - 0.5f;
// scale FFT output appropriately
float Ymag = 20*log10f( cabsf(Yfft[i] / (r * wsum)) );
// find frequency location of maximum magnitude
if (Ymag > Ypeak || i==0) {
Ypeak = Ymag;
fpeak = f;
}
// find peak side-lobe value, ignoring frequencies
// within a certain range of signal frequency
if ( fabsf(f-fy) > main_lobe_width )
max_sidelobe = Ymag > max_sidelobe ? Ymag : max_sidelobe;
}
// print results and check frequency location
printf(" desired resampling rate : %12.8f\n", r);
printf(" measured resampling rate : %12.8f (%u/%u)\n", r_actual, ny, nx);
printf(" peak spectrum : %12.8f dB (expected 0.0 dB)\n", Ypeak);
printf(" peak frequency : %12.8f (expected %-12.8f)\n", fpeak, fy);
printf(" max sidelobe : %12.8f dB (expected at least %.2f dB)\n", max_sidelobe, -As);
//
// export results
//
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,"m=%u;\n", m);
fprintf(fid,"npfb=%u;\n", npfb);
fprintf(fid,"r=%12.8f;\n", r);
fprintf(fid,"nx = %u;\n", nx);
fprintf(fid,"x = zeros(1,nx);\n");
for (i=0; i<nx; i++)
fprintf(fid,"x(%3u) = %12.4e + j*%12.4e;\n", i+1, crealf(x[i]), cimagf(x[i]));
fprintf(fid,"ny = %u;\n", ny);
fprintf(fid,"y = zeros(1,ny);\n");
for (i=0; i<ny; i++)
fprintf(fid,"y(%3u) = %12.4e + j*%12.4e;\n", i+1, crealf(y[i]), cimagf(y[i]));
fprintf(fid,"\n\n");
fprintf(fid,"%% plot frequency-domain result\n");
fprintf(fid,"nfft=2^nextpow2(max(nx,ny));\n");
fprintf(fid,"%% estimate PSD, normalize by array length\n");
fprintf(fid,"X=20*log10(abs(fftshift(fft(x,nfft)/length(x))));\n");
fprintf(fid,"Y=20*log10(abs(fftshift(fft(y,nfft)/length(y))));\n");
fprintf(fid,"G=max(X);\n");
fprintf(fid,"X=X-G;\n");
fprintf(fid,"Y=Y-G;\n");
fprintf(fid,"f=[0:(nfft-1)]/nfft-0.5;\n");
fprintf(fid,"figure;\n");
fprintf(fid,"if r>1, fx = f/r; fy = f; %% interpolated\n");
fprintf(fid,"else, fx = f; fy = f*r; %% decimated\n");
fprintf(fid,"end;\n");
fprintf(fid,"plot(fx,X,'Color',[0.5 0.5 0.5],fy,Y,'LineWidth',2);\n");
fprintf(fid,"grid on;\n");
fprintf(fid,"xlabel('normalized frequency');\n");
fprintf(fid,"ylabel('PSD [dB]');\n");
fprintf(fid,"legend('original','resampled','location','northeast');");
fprintf(fid,"axis([-0.5 0.5 -120 20]);\n");
fprintf(fid,"\n\n");
fprintf(fid,"%% plot time-domain result\n");
fprintf(fid,"tx=[0:(length(x)-1)];\n");
fprintf(fid,"ty=[0:(length(y)-1)]/r-m;\n");
fprintf(fid,"figure;\n");
fprintf(fid,"subplot(2,1,1);\n");
fprintf(fid," plot(tx,real(x),'-s','Color',[0.5 0.5 0.5],'MarkerSize',1,...\n");
fprintf(fid," ty,real(y),'-s','Color',[0.5 0 0], 'MarkerSize',1);\n");
fprintf(fid," legend('original','resampled','location','northeast');");
fprintf(fid," xlabel('time');\n");
fprintf(fid," ylabel('real');\n");
fprintf(fid,"subplot(2,1,2);\n");
fprintf(fid," plot(tx,imag(x),'-s','Color',[0.5 0.5 0.5],'MarkerSize',1,...\n");
fprintf(fid," ty,imag(y),'-s','Color',[0 0.5 0], 'MarkerSize',1);\n");
fprintf(fid," legend('original','resampled','location','northeast');");
fprintf(fid," xlabel('time');\n");
fprintf(fid," ylabel('imag');\n");
fclose(fid);
printf("results written to %s\n",OUTPUT_FILENAME);
printf("done.\n");
return 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;
}
int main(int argc, char*argv[]) {
// options
unsigned int k=4; // samples/symbol
unsigned int m=3; // filter delay [symbols]
float BT = 0.3f; // bandwidth-time product
// read properties from command line
int dopt;
while ((dopt = getopt(argc,argv,"uhk:m:b:")) != EOF) {
switch (dopt) {
case 'u':
case 'h': usage(); return 0;
case 'k': k = atoi(optarg); break;
case 'm': m = atoi(optarg); break;
case 'b': BT = atof(optarg); break;
default:
exit(1);
}
}
// validate input
if (k < 2) {
fprintf(stderr,"error: %s, k must be at least 2\n", argv[0]);
exit(1);
} else if (m < 1) {
fprintf(stderr,"error: %s, m must be at least 1\n", argv[0]);
exit(1);
} else if (BT <= 0.0f || BT >= 1.0f) {
fprintf(stderr,"error: %s, BT must be in (0,1)\n", argv[0]);
exit(1);
}
unsigned int i;
// derived values
unsigned int h_len = 2*k*m+1; // filter length
// arrays
float ht[h_len]; // transmit filter coefficients
float hr[h_len]; // recieve filter coefficients
// design transmit filter
liquid_firdes_gmsktx(k,m,BT,0.0f,ht);
// print results to screen
printf("gmsk transmit filter:\n");
for (i=0; i<h_len; i++)
printf(" ht(%3u) = %12.8f;\n", i+1, ht[i]);
//
// start of filter design procedure
//
float beta = BT; // prototype filter cut-off
float delta = 1e-2f; // filter design correction factor
// temporary arrays
float h_primef[h_len]; // temporary buffer for real coefficients
float g_primef[h_len]; //
float complex h_tx[h_len]; // impulse response of transmit filter
float complex h_prime[h_len]; // impulse response of 'prototype' filter
float complex g_prime[h_len]; // impulse response of 'gain' filter
float complex h_hat[h_len]; // impulse response of receive filter
float complex H_tx[h_len]; // frequency response of transmit filter
float complex H_prime[h_len]; // frequency response of 'prototype' filter
float complex G_prime[h_len]; // frequency response of 'gain' filter
float complex H_hat[h_len]; // frequency response of receive filter
// create 'prototype' matched filter
// for now use raised-cosine
liquid_firdes_nyquist(LIQUID_NYQUIST_RCOS,k,m,beta,0.0f,h_primef);
// create 'gain' filter to improve stop-band rejection
float fc = (0.7f + 0.1*beta) / (float)k;
float As = 60.0f;
liquid_firdes_kaiser(h_len, fc, As, 0.0f, g_primef);
// copy to fft input buffer, shifting appropriately
for (i=0; i<h_len; i++) {
h_prime[i] = h_primef[ (i+k*m)%h_len ];
g_prime[i] = g_primef[ (i+k*m)%h_len ];
h_tx[i] = ht[ (i+k*m)%h_len ];
}
// run ffts
fft_run(h_len, h_prime, H_prime, FFT_FORWARD, 0);
fft_run(h_len, g_prime, G_prime, FFT_FORWARD, 0);
fft_run(h_len, h_tx, H_tx, FFT_FORWARD, 0);
#if 0
// print results
for (i=0; i<h_len; i++)
printf("Ht(%3u) = %12.8f + j*%12.8f;\n", i+1, crealf(H_tx[i]), cimagf(H_tx[i]));
for (i=0; i<h_len; i++)
printf("H_prime(%3u) = %12.8f + j*%12.8f;\n", i+1, crealf(H_prime[i]), cimagf(H_prime[i]));
for (i=0; i<h_len; i++)
printf("G_prime(%3u) = %12.8f + j*%12.8f;\n", i+1, crealf(G_prime[i]), cimagf(G_prime[i]));
#endif
// find minimum of reponses
float H_tx_min = 0.0f;
float H_prime_min = 0.0f;
float G_prime_min = 0.0f;
for (i=0; i<h_len; i++) {
if (i==0 || crealf(H_tx[i]) < H_tx_min) H_tx_min = crealf(H_tx[i]);
if (i==0 || crealf(H_prime[i]) < H_prime_min) H_prime_min = crealf(H_prime[i]);
if (i==0 || crealf(G_prime[i]) < G_prime_min) G_prime_min = crealf(G_prime[i]);
}
// compute 'prototype' response, removing minima, and add correction factor
for (i=0; i<h_len; i++) {
// compute response necessary to yeild prototype response (not exact, but close)
H_hat[i] = crealf(H_prime[i] - H_prime_min + delta) / crealf(H_tx[i] - H_tx_min + delta);
// include additional term to add stop-band suppression
H_hat[i] *= crealf(G_prime[i] - G_prime_min) / crealf(G_prime[0]);
}
// compute ifft and copy response
fft_run(h_len, H_hat, h_hat, FFT_REVERSE, 0);
for (i=0; i<h_len; i++)
hr[i] = crealf( h_hat[(i+k*m+1)%h_len] ) / (float)(k*h_len);
//
// end of filter design procedure
//
// print results to screen
printf("gmsk receive filter:\n");
for (i=0; i<h_len; i++)
printf(" hr(%3u) = %12.8f;\n", i+1, hr[i]);
// compute isi
float rxy0 = liquid_filter_crosscorr(ht,h_len, hr,h_len, 0);
float isi_rms = 0.0f;
for (i=1; i<2*m; i++) {
float e = liquid_filter_crosscorr(ht,h_len, hr,h_len, i*k) / rxy0;
isi_rms += e*e;
}
isi_rms = sqrtf(isi_rms / (float)(2*m-1));
printf("\n");
printf("ISI (RMS) = %12.8f dB\n", 20*log10f(isi_rms));
//
// 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,"\n\n");
fprintf(fid,"k = %u;\n", k);
fprintf(fid,"m = %u;\n", m);
fprintf(fid,"beta = %f;\n", BT);
fprintf(fid,"h_len = 2*k*m+1;\n");
fprintf(fid,"nfft = 1024;\n");
fprintf(fid,"ht = zeros(1,h_len);\n");
fprintf(fid,"hp = zeros(1,h_len);\n");
fprintf(fid,"hr = zeros(1,h_len);\n");
// print results
for (i=0; i<h_len; i++) fprintf(fid,"ht(%3u) = %12.4e;\n", i+1, ht[i] / k);
for (i=0; i<h_len; i++) fprintf(fid,"hr(%3u) = %12.4e;\n", i+1, hr[i] * k);
for (i=0; i<h_len; i++) fprintf(fid,"hp(%3u) = %12.4e;\n", i+1, h_primef[i]);
fprintf(fid,"hc = k*conv(ht,hr);\n");
// plot results
fprintf(fid,"f = [0:(nfft-1)]/nfft - 0.5;\n");
fprintf(fid,"Ht = 20*log10(abs(fftshift(fft(ht, nfft))));\n");
fprintf(fid,"Hp = 20*log10(abs(fftshift(fft(hp/k,nfft))));\n");
fprintf(fid,"Hr = 20*log10(abs(fftshift(fft(hr, nfft))));\n");
fprintf(fid,"Hc = 20*log10(abs(fftshift(fft(hc/k,nfft))));\n");
fprintf(fid,"\n");
fprintf(fid,"figure;\n");
fprintf(fid,"plot(f,Ht,'LineWidth',1,'Color',[0.00 0.25 0.50],...\n");
fprintf(fid," f,Hp,'LineWidth',1,'Color',[0.80 0.80 0.80],...\n");
fprintf(fid," f,Hr,'LineWidth',1,'Color',[0.00 0.50 0.25],...\n");
fprintf(fid," f,Hc,'LineWidth',2,'Color',[0.50 0.00 0.00],...\n");
fprintf(fid," [-0.5/k 0.5/k], [1 1]*20*log10(0.5),'or');\n");
fprintf(fid,"legend('transmit','prototype','receive','composite','alias points',1);\n");
fprintf(fid,"xlabel('Normalized Frequency');\n");
fprintf(fid,"ylabel('PSD');\n");
fprintf(fid,"grid on;\n");
fprintf(fid,"axis([-0.5 0.5 -100 20]);\n");
fprintf(fid,"\n");
fprintf(fid,"figure;\n");
fprintf(fid,"tr = [ -k*m:k*m]/k;\n");
fprintf(fid,"tc = [-2*k*m:2*k*m]/k;\n");
fprintf(fid,"ic = [0:k:(4*k*m)]+1;\n");
fprintf(fid,"subplot(2,1,1);\n");
fprintf(fid," plot(tr,ht,'-x', tr,hr,'-x');\n");
fprintf(fid," legend('transmit','receive',1);\n");
fprintf(fid," xlabel('Time');\n");
fprintf(fid," ylabel('GMSK Tx/Rx Filters');\n");
fprintf(fid," grid on;\n");
fprintf(fid," axis([-2*m 2*m floor(5*min([hr ht]))/5 ceil(5*max([hr ht]))/5]);\n");
fprintf(fid,"subplot(2,1,2);\n");
fprintf(fid," plot(tc,hc,'-x', tc(ic),hc(ic),'or');\n");
fprintf(fid," xlabel('Time');\n");
fprintf(fid," ylabel('GMSK Composite Response');\n");
fprintf(fid," grid on;\n");
fprintf(fid," axis([-2*m 2*m -0.2 1.2]);\n");
fprintf(fid," axis([-2*m 2*m floor(5*min(hc))/5 ceil(5*max(hc))/5]);\n");
fclose(fid);
printf("results written to %s.\n", OUTPUT_FILENAME);
return 0;
}
void
InputProcessor::fftAnalyze() {
fft_reorder();
fft_run();
}
// Design GMSK receive filter
// _k : samples/symbol
// _m : symbol delay
// _beta : rolloff factor (0 < beta <= 1)
// _dt : fractional sample delay
// _h : output coefficient buffer (length: 2*k*m+1)
void liquid_firdes_gmskrx(unsigned int _k,
unsigned int _m,
float _beta,
float _dt,
float * _h)
{
// validate input
if ( _k < 1 ) {
fprintf(stderr,"error: liquid_firdes_gmskrx(): k must be greater than 0\n");
exit(1);
} else if ( _m < 1 ) {
fprintf(stderr,"error: liquid_firdes_gmskrx(): m must be greater than 0\n");
exit(1);
} else if ( (_beta < 0.0f) || (_beta > 1.0f) ) {
fprintf(stderr,"error: liquid_firdes_gmskrx(): beta must be in [0,1]\n");
exit(1);
} else;
unsigned int k = _k;
unsigned int m = _m;
float BT = _beta;
// internal options
float beta = BT; // prototype filter cut-off
float delta = 1e-3f; // filter design correction factor
liquid_firfilt_type prototype = LIQUID_FIRFILT_KAISER; // Nyquist prototype
unsigned int i;
// derived values
unsigned int h_len = 2*k*m+1; // filter length
// arrays
float ht[h_len]; // transmit filter coefficients
float hr[h_len]; // recieve filter coefficients
// design transmit filter
liquid_firdes_gmsktx(k,m,BT,0.0f,ht);
//
// start of filter design procedure
//
// 'internal' arrays
float h_primef[h_len]; // temporary buffer for real 'prototype' coefficients
float g_primef[h_len]; // temporary buffer for real 'gain' coefficient
float complex h_tx[h_len]; // impulse response of transmit filter
float complex h_prime[h_len]; // impulse response of 'prototype' filter
float complex g_prime[h_len]; // impulse response of 'gain' filter
float complex h_hat[h_len]; // impulse response of receive filter
float complex H_tx[h_len]; // frequency response of transmit filter
float complex H_prime[h_len]; // frequency response of 'prototype' filter
float complex G_prime[h_len]; // frequency response of 'gain' filter
float complex H_hat[h_len]; // frequency response of receive filter
// create 'prototype' matched filter
liquid_firdes_nyquist(prototype,k,m,beta,0.0f,h_primef);
// create 'gain' filter to improve stop-band rejection
float fc = (0.7f + 0.1*beta) / (float)k;
float As = 60.0f;
liquid_firdes_kaiser(h_len, fc, As, 0.0f, g_primef);
// copy to fft input buffer, shifting appropriately
for (i=0; i<h_len; i++) {
h_prime[i] = h_primef[ (i+k*m)%h_len ];
g_prime[i] = g_primef[ (i+k*m)%h_len ];
h_tx[i] = ht[ (i+k*m)%h_len ];
}
// run ffts
fft_run(h_len, h_prime, H_prime, LIQUID_FFT_FORWARD, 0);
fft_run(h_len, g_prime, G_prime, LIQUID_FFT_FORWARD, 0);
fft_run(h_len, h_tx, H_tx, LIQUID_FFT_FORWARD, 0);
// find minimum of reponses
float H_tx_min = 0.0f;
float H_prime_min = 0.0f;
float G_prime_min = 0.0f;
for (i=0; i<h_len; i++) {
if (i==0 || crealf(H_tx[i]) < H_tx_min) H_tx_min = crealf(H_tx[i]);
if (i==0 || crealf(H_prime[i]) < H_prime_min) H_prime_min = crealf(H_prime[i]);
if (i==0 || crealf(G_prime[i]) < G_prime_min) G_prime_min = crealf(G_prime[i]);
}
// compute 'prototype' response, removing minima, and add correction factor
for (i=0; i<h_len; i++) {
// compute response necessary to yeild prototype response (not exact, but close)
H_hat[i] = crealf(H_prime[i] - H_prime_min + delta) / crealf(H_tx[i] - H_tx_min + delta);
// include additional term to add stop-band suppression
H_hat[i] *= crealf(G_prime[i] - G_prime_min) / crealf(G_prime[0]);
}
// compute ifft and copy response
fft_run(h_len, H_hat, h_hat, LIQUID_FFT_BACKWARD, 0);
for (i=0; i<h_len; i++)
hr[i] = crealf( h_hat[(i+k*m+1)%h_len] ) / (float)(k*h_len);
// copy result, scaling by (samples/symbol)^2
for (i=0; i<h_len; i++)
_h[i] = hr[i]*_k*_k;
}
int main()
{
int fd=inotify_init();
int in=inotify_add_watch(fd,"/dev/shm",IN_CLOSE_WRITE);
char buf[BUF_LEN];
pgm_init();
fft_init();
if (!glfwInit())
exit(EXIT_FAILURE);
GLFWwindow* window = glfwCreateWindow(width[0]+width[1], (int)fmax(2*height[0],2*height[1]),
"gig-e-camera", NULL, NULL);
glfwMakeContextCurrent(window);
const int n_tex=4;
GLuint texture[n_tex];
glGenTextures( n_tex, texture );
int i;
for(i=0;i<n_tex;i++){
glBindTexture( GL_TEXTURE_2D, texture[i] );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
GL_NEAREST );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
glTexImage2D(GL_TEXTURE_2D,0,GL_LUMINANCE,width[i/2],height[i/2],0,
GL_LUMINANCE,GL_UNSIGNED_SHORT,0);
}
glEnable(GL_TEXTURE_2D);
while (1){
int len, i = 0;
len = read (fd, buf, BUF_LEN);
if(len<=0)
printf("error\n");
while (i < len) {
struct inotify_event *event;
event = (struct inotify_event *) &buf[i];
printf ("wd=%d mask=%u cookie=%u len=%u ",
event->wd, event->mask,
event->cookie, event->len);
if (event->len)
printf ("name=%s\n", event->name);
else
printf("\n");
i += EVENT_SIZE + event->len;
}
{
int i;
fft_fill(); fft_run();
for(i=0;i<2;i++){
glBindTexture( GL_TEXTURE_2D, texture[2*i] );
glTexSubImage2D(GL_TEXTURE_2D,0,0,0,width[i],height[i],GL_LUMINANCE,GL_UNSIGNED_SHORT,kspace[i]);
glBindTexture( GL_TEXTURE_2D, texture[2*i+1] );
glTexSubImage2D(GL_TEXTURE_2D,0,0,0,width[i],height[i],GL_LUMINANCE,GL_UNSIGNED_SHORT,image[i]);
}
{
int win_width,win_height;
glfwGetFramebufferSize(window, &win_width, &win_height);
glViewport(0, 0, win_width, win_height);
}
glClear(GL_COLOR_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, width[0]+width[1], 0,fmax(2*height[0],2*height[1]), 1.f, -1.f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glColor3f(1.f,1.f,1.f);
draw_quad(texture[0],0,0,width[0],height[0]);
draw_quad(texture[1],0,height[0],width[0],height[0]);
draw_quad(texture[2],width[0],0,width[1],height[1]);
draw_quad(texture[3],width[0],height[1],width[1],height[1]);
glfwSwapBuffers(window);
}
}
glfwTerminate();
}
int main(int argc, char*argv[])
{
// options
unsigned int num_channels=16; // number of channels
unsigned int m = 5; // filter semi-length (symbols)
unsigned int num_symbols=25; // number of symbols
float As = 80.0f; // filter stop-band attenuation
int dopt;
while ((dopt = getopt(argc,argv,"hM:m:s:n:")) != EOF) {
switch (dopt) {
case 'h': usage(); return 0;
case 'M': num_channels = atoi(optarg); break;
case 'm': m = atoi(optarg); break;
case 's': As = atof(optarg); break;
case 'n': num_symbols = atof(optarg); break;
default:
exit(1);
}
}
unsigned int i;
// validate input
if (num_channels < 2 || num_channels % 2) {
fprintf(stderr,"error: %s, number of channels must be greater than 2 and even\n", argv[0]);
exit(1);
} else if (m == 0) {
fprintf(stderr,"error: %s, filter semi-length must be greater than zero\n", argv[0]);
exit(1);
} else if (num_symbols == 0) {
fprintf(stderr,"error: %s, number of symbols must be greater than zero", argv[0]);
exit(1);
}
// derived values
unsigned int num_samples = num_channels * num_symbols;
// allocate arrays
float complex x[num_samples];
float complex y[num_samples];
// generate input signal
unsigned int w_len = (unsigned int)(0.4*num_samples);
for (i=0; i<num_samples; i++) {
//x[i] = (i==0) ? 1.0f : 0.0f;
//x[i] = cexpf( (-0.05f + 0.07f*_Complex_I)*i ); // decaying complex exponential
x[i] = cexpf( _Complex_I * (1.3f*i - 0.007f*i*i) );
x[i] *= i < w_len ? hamming(i,w_len) : 0.0f;
//x[i] = (i==0) ? 1.0f : 0.0f;
}
// create filterbank objects from prototype
firpfbch2_crcf qa = firpfbch2_crcf_create_kaiser(LIQUID_ANALYZER, num_channels, m, As);
firpfbch2_crcf qs = firpfbch2_crcf_create_kaiser(LIQUID_SYNTHESIZER, num_channels, m, As);
firpfbch2_crcf_print(qa);
firpfbch2_crcf_print(qs);
// run channelizer
float complex Y[num_channels];
for (i=0; i<num_samples; i+=num_channels/2) {
// run analysis filterbank
firpfbch2_crcf_execute(qa, &x[i], Y);
// run synthesis filterbank
firpfbch2_crcf_execute(qs, Y, &y[i]);
}
// destroy fiterbank objects
firpfbch2_crcf_destroy(qa); // analysis fitlerbank
firpfbch2_crcf_destroy(qs); // synthesis filterbank
// print output
for (i=0; i<num_samples; i++)
printf("%4u : %12.8f + %12.8fj\n", i, crealf(y[i]), cimagf(y[i]));
// compute RMSE
float rmse = 0.0f;
unsigned int delay = 2*num_channels*m - num_channels/2 + 1;
for (i=0; i<num_samples; i++) {
float complex err = y[i] - (i < delay ? 0.0f : x[i-delay]);
rmse += crealf( err*conjf(err) );
}
rmse = sqrtf( rmse/(float)num_samples );
printf("rmse : %12.4e\n", rmse);
//
// EXPORT DATA TO FILES
//
FILE * fid = NULL;
fid = fopen(OUTPUT_FILENAME_TIME,"w");
fprintf(fid,"# %s: auto-generated file\n", OUTPUT_FILENAME_TIME);
fprintf(fid,"#\n");
fprintf(fid,"# %8s %12s %12s %12s %12s %12s %12s\n",
"time", "real(x)", "imag(x)", "real(y)", "imag(y)", "real(e)", "imag(e)");
// save input and output arrays
for (i=0; i<num_samples; i++) {
float complex e = (i < delay) ? 0.0f : y[i] - x[i-delay];
fprintf(fid," %8.1f %12.4e %12.4e %12.4e %12.4e %12.4e %12.4e\n",
(float)i,
crealf(x[i]), cimagf(x[i]),
crealf(y[i]), cimagf(y[i]),
crealf(e), cimagf(e));
}
fclose(fid);
printf("results written to '%s'\n", OUTPUT_FILENAME_TIME);
//
// export frequency data
//
unsigned int nfft = 2048;
float complex y_time[nfft];
float complex y_freq[nfft];
for (i=0; i<nfft; i++)
y_time[i] = i < num_samples ? y[i] : 0.0f;
fft_run(nfft, y_time, y_freq, LIQUID_FFT_FORWARD, 0);
// filter spectrum
unsigned int h_len = 2*num_channels*m+1;
float h[h_len];
float fc = 0.5f/(float)num_channels;
liquid_firdes_kaiser(h_len, fc, As, 0.0f, h);
float complex h_time[nfft];
float complex h_freq[nfft];
for (i=0; i<nfft; i++)
h_time[i] = i < h_len ? 2*h[i]*fc : 0.0f;
fft_run(nfft, h_time, h_freq, LIQUID_FFT_FORWARD, 0);
// error spectrum
float complex e_time[nfft];
float complex e_freq[nfft];
for (i=0; i<nfft; i++)
e_time[i] = i < delay || i > num_samples ? 0.0f : y[i] - x[i-delay];
fft_run(nfft, e_time, e_freq, LIQUID_FFT_FORWARD, 0);
fid = fopen(OUTPUT_FILENAME_FREQ,"w");
fprintf(fid,"# %s: auto-generated file\n", OUTPUT_FILENAME_FREQ);
fprintf(fid,"#\n");
fprintf(fid,"# nfft = %u\n", nfft);
fprintf(fid,"# %12s %12s %12s %12s\n", "freq", "PSD [dB]", "filter [dB]", "error [dB]");
// save input and output arrays
for (i=0; i<nfft; i++) {
float f = (float)i/(float)nfft - 0.5f;
unsigned int k = (i + nfft/2)%nfft;
fprintf(fid," %12.8f %12.8f %12.8f %12.8f\n",
f,
20*log10f(cabsf(y_freq[k])),
20*log10f(cabsf(h_freq[k])),
20*log10f(cabsf(e_freq[k])));
}
fclose(fid);
printf("results written to '%s'\n", OUTPUT_FILENAME_FREQ);
printf("done.\n");
return 0;
}
