mirror of
https://github.com/rtlsdrblog/rtl-sdr-blog.git
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rtl_power: more lowpass options
Signed-off-by: Steve Markgraf <steve@steve-m.de>
This commit is contained in:
Kyle Keen
Steve Markgraf
parent
8f1d108122
commit
c5b8a21300
123
src/rtl_power.c
123
src/rtl_power.c
@ -34,7 +34,6 @@
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* general astronomy usefulness
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* multiple dongles
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* multiple FFT workers
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* bandwidths smaller than 1MHz (with optional xlate?)
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* check edge cropping for off-by-one and rounding errors
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* 1.8MS/s for hiding xtal harmonics
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*/
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@ -88,6 +87,7 @@ struct tuning_state
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long *avg; /* length == 2^bin_e */
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int samples;
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int downsample;
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int downsample_passes; /* for the recursive filter */
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double crop;
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//pthread_rwlock_t avg_lock;
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//pthread_mutex_t avg_mutex;
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@ -103,6 +103,8 @@ struct tuning_state
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struct tuning_state tunes[MAX_TUNES];
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int tune_count = 0;
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int boxcar = 1;
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void usage(void)
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{
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fprintf(stderr,
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@ -127,9 +129,11 @@ void usage(void)
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"\t[-w window (default: rectangle)]\n"
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"\t (hamming, blackman, blackman-harris, hann-poisson, bartlett, youssef)\n"
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// kaiser
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"\t[-c crop_percent (default: 0%, recommended: 20%%-50%%)]\n"
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"\t[-c crop_percent (default: 0%%, recommended: 20%%-50%%)]\n"
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"\t (discards data at the edges, 100%% discards everything)\n"
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"\t (has no effect for bins > 1MHz or bandwidth < 1MHz)\n"
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"\t (has no effect for bins larger than 1MHz)\n"
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"\t[-F enables low-leakage downsample filter (default: off)]\n"
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"\t (has bad roll off, try with '-c 50%%')\n"
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"\n"
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"CSV FFT output columns:\n"
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"\tdate, time, Hz low, Hz high, Hz step, samples, dbm, dbm, ...\n\n"
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@ -144,7 +148,7 @@ void usage(void)
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"\trtl_power -f ... -e 1h | gzip > log.csv.gz\n"
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"\t (collect data for one hour and compress it on the fly)\n\n"
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"Convert CSV to a waterfall graphic with:\n"
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"\thttp://kmkeen.com/tmp/heatmap.py.txt\n");
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"\t http://kmkeen.com/tmp/heatmap.py.txt \n");
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exit(1);
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}
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@ -477,7 +481,8 @@ void frequency_range(char *arg, double crop)
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// do we want the fewest ranges (easy) or the fewest bins (harder)?
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{
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char *start, *stop, *step;
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int i, j, upper, lower, max_size, bw_seen, bw_used, bin_e, buf_len, downsample;
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int i, j, upper, lower, max_size, bw_seen, bw_used, bin_e, buf_len;
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int downsample, downsample_passes;
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double bin_size;
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struct tuning_state *ts;
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/* hacky string parsing */
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@ -492,21 +497,28 @@ void frequency_range(char *arg, double crop)
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stop[-1] = ':';
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step[-1] = ':';
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downsample = 1;
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if ((upper - lower) < 1000000) {
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crop = 0.0;}
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downsample_passes = 0;
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/* evenly sized ranges, as close to 2MHz as possible */
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for (i=1; i<1500; i++) {
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bw_seen = (upper - lower) / i;
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bw_used = (int)((double)(bw_seen) / (1.0 - crop));
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if (bw_used > 2000000) {
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continue;}
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if (bw_used < 1000000) {
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downsample = 2000000 / bw_seen;
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bw_used = bw_seen * downsample;
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}
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tune_count = i;
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break;
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}
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/* unless small bandwidth */
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if (bw_used < 1000000) {
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tune_count = 1;}
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if (boxcar && bw_used < 1000000) {
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downsample = 2000000 / bw_used;
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bw_used = bw_used * downsample;
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}
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while (bw_used < 1000000) { /* not boxcar */
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downsample_passes++;
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downsample = 1 << downsample_passes;
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bw_used = (int)((double)(bw_seen * downsample) / (1.0 - crop));
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}
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/* number of bins is power-of-two, bin size is under limit */
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for (i=1; i<=21; i++) {
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bin_e = i;
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@ -526,7 +538,7 @@ void frequency_range(char *arg, double crop)
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fprintf(stderr, "Error: bandwidth too wide.\n");
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exit(1);
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}
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buf_len = (1<<bin_e) * 2 * downsample;
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buf_len = 2 * (1<<bin_e) * downsample;
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if (buf_len < DEFAULT_BUF_LENGTH) {
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buf_len = DEFAULT_BUF_LENGTH;
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}
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@ -539,6 +551,7 @@ void frequency_range(char *arg, double crop)
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ts->samples = 0;
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ts->crop = crop;
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ts->downsample = downsample;
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ts->downsample_passes = downsample_passes;
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ts->avg = (long*)malloc((1<<bin_e) * sizeof(long));
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if (!ts->avg) {
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fprintf(stderr, "Error: malloc.\n");
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@ -578,6 +591,58 @@ void retune(rtlsdr_dev_t *d, int freq)
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fprintf(stderr, "Error: bad retune.\n");}
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}
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void fifth_order(int16_t *data, int length)
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/* for half of interleaved data */
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{
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int i;
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int a, b, c, d, e, f;
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a = data[0];
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b = data[2];
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c = data[4];
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d = data[6];
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e = data[8];
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f = data[10];
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/* a downsample should improve resolution, so don't fully shift */
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/* ease in instead of being stateful */
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data[0] = ((a+b)*10 + (c+d)*5 + d + f) >> 4;
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data[2] = ((b+c)*10 + (a+d)*5 + e + f) >> 4;
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data[4] = (a + (b+e)*5 + (c+d)*10 + f) >> 4;
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for (i=12; i<length; i+=4) {
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a = c;
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b = d;
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c = e;
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d = f;
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e = data[i-2];
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f = data[i];
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data[i/2] = (a + (b+e)*5 + (c+d)*10 + f) >> 4;
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}
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}
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void remove_dc(int16_t *data, int length)
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/* works on interleaved data */
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{
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int i;
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int16_t ave;
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long sum = 0L;
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for (i=0; i < length; i+=2) {
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sum += data[i];
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}
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ave = (int16_t)(sum / (long)(length));
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if (ave == 0) {
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return;}
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for (i=0; i < length; i+=2) {
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data[i] -= ave;
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}
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}
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void downsample_iq(int16_t *data, int length)
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{
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fifth_order(data, length);
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//remove_dc(data, length);
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fifth_order(data+1, length-1);
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//remove_dc(data+1, length-1);
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}
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void scanner(void)
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{
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int i, j, j2, f, n_read, offset, bin_e, bin_len, buf_len, ds;
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@ -601,20 +666,28 @@ void scanner(void)
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rms_power(ts);
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continue;
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}
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/* sign and downsample */
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/* prep for fft */
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for (j=0; j<buf_len; j++) {
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fft_buf[j] = 0;
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fft_buf[j] = (int16_t)ts->buf8[j] - 127;
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}
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ds = ts->downsample;
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j=0, j2=0;
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while (j < buf_len) {
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fft_buf[j2] += (int16_t)ts->buf8[j] - 127;
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fft_buf[j2+1] += (int16_t)ts->buf8[j+1] - 127;
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j += 2;
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if (j % (ds*2) == 0) {
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j2 += 2;}
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if (boxcar) {
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j=2, j2=0;
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while (j < buf_len) {
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fft_buf[j2] += fft_buf[j];
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fft_buf[j2+1] += fft_buf[j+1];
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j += 2;
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if (j % (ds*2) == 0) {
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j2 += 2;}
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}
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} else { /* recursive */
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for (j=0; j < ts->downsample_passes; j++) {
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downsample_iq(fft_buf, buf_len >> j);
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}
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}
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/* fft */
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remove_dc(fft_buf, buf_len >> j);
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remove_dc(fft_buf+1, (buf_len >> j) - 1);
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/* window function and fft */
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for (offset=0; offset<(buf_len/ds); offset+=(2*bin_len)) {
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// todo, let rect skip this
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for (j=0; j<bin_len; j++) {
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@ -707,8 +780,9 @@ int main(int argc, char **argv)
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char t_str[50];
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struct tm *cal_time;
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double (*window_fn)(int, int) = rectangle;
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freq_optarg = "";
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while ((opt = getopt(argc, argv, "f:i:s:t:d:g:p:e:w:c:1h")) != -1) {
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while ((opt = getopt(argc, argv, "f:i:s:t:d:g:p:e:w:c:1Fh")) != -1) {
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switch (opt) {
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case 'f': // lower:upper:bin_size
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freq_optarg = strdup(optarg);
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@ -762,6 +836,9 @@ int main(int argc, char **argv)
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case '1':
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single = 1;
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break;
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case 'F':
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boxcar = 0;
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break;
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case 'h':
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default:
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usage();
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