osmocom-sdr

osmocom-sdr@lists.osmocom.org

906 discussions

Scanning with rtl_fm
by Alan Corey 28 Apr '13

28 Apr '13

I'm using rtl_fm in a scanning (nbfm) situation, and even with the antenna input disconnected and terminated, I get a burst of noise that sounds like a squelch tail maybe once each scan cycle. They're a little over 1 second apart. I've tried setting the squelch up to 10000 where I don't get signals anymore, but I still get the noise. I discovered that if you scan and have the output be a raw audio file, nothing gets recorded when nothing breaks squelch. This makes time-lapse recordings where all the pauses are taken out. Very nice, except for the noise bursts. I'm using: #!/bin/sh rtl_fm -N -S -l 132 -p 102 -f 854040000 -f 854240000 -f 854315000 -f 854415000 -f \ 854490000 -f 854540000 -f 855165000 -f 855240000 -f 858790000 -f 867350000 \ -f 867715000 /tmp/`date +"%Y-%m-%d_%H%M.raw"` and recorded overnight, but I mostly got noise bursts. Alan ----- Radio Astronomy - the ultimate DX

2 2

gr-iqbal or gr-iqbalance?
by Wojciech Kazubski 28 Apr '13

28 Apr '13

Hello! This is a minor issue, but may lead to some misunderstanding (and seach failures) in future. The package to correct IQ imbalance is registered at http://cgit.osmocom.org as gr-iqbal but project name set in line 24 of toplevel CMakeList.txt is gr- iqbalance. Which name should be used while building packages, etc.? BTW: Is there any homepage for gr-iqbal/gr-iqbalance? Wojciech Kazubski

2 1

OpenSourceDABplusSDRreceiver
by mrzfrn 26 Apr '13

26 Apr '13

"However, nobody has implemented a full and open DAB+ SDR receiver yet" Not true, look at http://www.sdr-j.tk/index.html Francesco

3 4

[PATCH 1/1] add -S (synchronous) mode to rtl_fm
by Stuart Henderson 23 Apr '13

23 Apr '13

The enclosed diff adds a synchronous mode to rtl_fm. This helps OpenBSD (where libusb async isn't yet working). Signed-off-by: Stuart Henderson <stu(a)spacehopper.org> --- src/rtl_fm.c | 29 +++++++++++++++++++++++++---- 1 file changed, 25 insertions(+), 4 deletions(-) diff --git a/src/rtl_fm.c b/src/rtl_fm.c index e8ebb77..a71e287 100644 --- a/src/rtl_fm.c +++ b/src/rtl_fm.c @@ -128,6 +128,7 @@ void usage(void) "\t[-E sets lower edge tuning (default: center)]\n" "\t[-N enables NBFM mode (default: on)]\n" "\t[-W enables WBFM mode (default: off)]\n" + "\t[-S force sync output (default: async)]\n" "\t (-N -s 170k -o 4 -A fast -r 32k -l 0 -D)\n" "\tfilename (a '-' dumps samples to stdout)\n" "\t (omitting the filename also uses stdout)\n\n" @@ -723,12 +724,14 @@ int main(int argc, char **argv) uint32_t dev_index = 0; int device_count; int ppm_error = 0; + int sync_mode = 0; char vendor[256], product[256], serial[256]; + fm_init(&fm); pthread_mutex_init(&data_ready, NULL); pthread_mutex_init(&data_write, NULL); - while ((opt = getopt(argc, argv, "d:f:g:s:b:l:o:t:r:p:EFA:NWMULRDC")) != -1) { + while ((opt = getopt(argc, argv, "d:f:g:s:b:l:o:t:r:p:EFA:NWMULRDSC")) != -1) { switch (opt) { case 'd': dev_index = atoi(optarg); @@ -815,6 +818,9 @@ int main(int argc, char **argv) case 'R': fm.mode_demod = &raw_demod; break; + case 'S': + sync_mode = 1; + break; default: usage(); break; @@ -921,9 +927,24 @@ int main(int argc, char **argv) fprintf(stderr, "WARNING: Failed to reset buffers.\n");} pthread_create(&demod_thread, NULL, demod_thread_fn, (void *)(&fm)); - rtlsdr_read_async(dev, rtlsdr_callback, (void *)(&fm), - DEFAULT_ASYNC_BUF_NUMBER, - lcm_post[fm.post_downsample] * DEFAULT_BUF_LENGTH); + if (sync_mode) { + fprintf(stderr, "Reading samples in sync mode...\n"); + while (!do_exit) { + r = rtlsdr_read_sync(dev, &fm.buf, + lcm_post[fm.post_downsample] * DEFAULT_BUF_LENGTH, + &fm.buf_len); + if (r < 0) { + fprintf(stderr, "WARNING: sync read failed.\n"); + break; + } + full_demod(&fm); + } + } else { + fprintf(stderr, "Reading samples in async mode...\n"); + rtlsdr_read_async(dev, rtlsdr_callback, (void *)(&fm), + DEFAULT_ASYNC_BUF_NUMBER, + lcm_post[fm.post_downsample] * DEFAULT_BUF_LENGTH); + } if (do_exit) { fprintf(stderr, "\nUser cancel, exiting...\n");} -- 1.8.1.3

3 3

rtl_test patch
by Nuno Gonçalves 21 Apr '13

21 Apr '13

Corrects bugs where: Cumulative PPM error is always "342" if execution stopped before first PPM_DURATION. PPM error alias to wrong values if over +-1045 (this happens quite a lot actually due to bug reported at [1]). Behavior changes: Cumulative PPM error value is now printed every PPM_DURATION so the user can check when it is settled. [1] http://lists.osmocom.org/pipermail/osmocom-sdr/2013-April/000584.html Thanks, Nuno Signed-off-by: Nuno Goncalves <nunojpg(a)gmail.com> diff --git a/src/rtl_test.c b/src/rtl_test.c index f5a56b8..c705e04 100644 --- a/src/rtl_test.c +++ b/src/rtl_test.c @@ -55,6 +55,8 @@ static int ppm_benchmark = 0; static int64_t ppm_count = 0L; static int64_t ppm_total = 0L; +static uint32_t samp_rate = DEFAULT_SAMPLE_RATE; + #ifndef _WIN32 static struct timespec ppm_start; static struct timespec ppm_recent; @@ -108,6 +110,7 @@ static void rtlsdr_callback(unsigned char *buf, uint32_t len, void *ctx) { uint32_t i, lost = 0; int64_t ns; + int real_rate; if (uninit) { bcnt = buf[0]; @@ -141,17 +144,23 @@ static void rtlsdr_callback(unsigned char *buf, uint32_t len, void *ctx) if (ppm_now.tv_sec - ppm_recent.tv_sec > PPM_DURATION) { ns = 1000000000L * (int64_t)(ppm_now.tv_sec - ppm_recent.tv_sec); ns += (int64_t)(ppm_now.tv_nsec - ppm_recent.tv_nsec); - printf("real sample rate: %i\n", + printf("real sample rate: %i", (int)((1000000000L * ppm_count / 2L) / ns)); - #ifndef __APPLE__ - clock_gettime(CLOCK_REALTIME, &ppm_recent); - #else - gettimeofday(&tv, NULL); - ppm_recent.tv_sec = tv.tv_sec; - ppm_recent.tv_nsec = tv.tv_usec*1000; - #endif + ppm_total += ppm_count / 2L; ppm_count = 0L; + + #ifndef _WIN32 + ns = 1000000000L * (int64_t)(ppm_now.tv_sec - ppm_start.tv_sec); + ns += (int64_t)(ppm_now.tv_nsec - ppm_start.tv_nsec); + real_rate = (int)(ppm_total * 1000000000L / ns); + printf(" cumulative PPM error: %.1f\n", + (1000000.0 * (real_rate - (int)samp_rate)) / samp_rate); + #else + printf("\n"); + #endif + + ppm_recent = ppm_now; } #endif } @@ -213,13 +222,10 @@ int main(int argc, char **argv) int sync_mode = 0; uint8_t *buffer; uint32_t dev_index = 0; - uint32_t samp_rate = DEFAULT_SAMPLE_RATE; uint32_t out_block_size = DEFAULT_BUF_LENGTH; int device_count; int count; int gains[100]; - int real_rate; - int64_t ns; while ((opt = getopt(argc, argv, "d:s:b:tpS::")) != -1) { switch (opt) { @@ -365,15 +371,6 @@ int main(int argc, char **argv) if (do_exit) { fprintf(stderr, "\nUser cancel, exiting...\n"); - if (ppm_benchmark) { -#ifndef _WIN32 - ns = 1000000000L * (int64_t)(ppm_recent.tv_sec - ppm_start.tv_sec); - ns += (int64_t)(ppm_recent.tv_nsec - ppm_start.tv_nsec); - real_rate = (int)(ppm_total * 1000000000L / ns); - printf("Cumulative PPM error: %i\n", - (int)round((double)(1000000 * (real_rate - (int)samp_rate)) / (double)samp_rate)); -#endif - } } else fprintf(stderr, "\nLibrary error %d, exiting...\n", r);

1 0

rtlsdr not reseting buffers
by Nuno Gonçalves 21 Apr '13

21 Apr '13

rtlsdr in async mode is returning buffers full with data from previous calls. I noticed that sometimes the first async callbacks would return TOO QUICKLY so that it would be impossible to have sampled that data. This might be because lib-usb have previous transfers submitted and not cleared? I compiled rtl_test with a small modification that will print the sampling time if it is much lower than expected. BUF_LENGTH is (16 * 16384)=256K, and SAMPLE_RATE is 2048000, so a full buffer should take about 64ms. You can see that in this example the async callback is returned after 7.79ms (and the following one 1.47ms later). So the data must be old. The ns printf nuno@ubuntu:~/Desktop/rtl-sdr/build/src$ ./rtl_test -p Found 1 device(s): 0: ezcap USB 2.0 DVB-T/DAB/FM dongle Using device 0: ezcap USB 2.0 DVB-T/DAB/FM dongle Found Rafael Micro R820T tuner Supported gain values (29): 0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6 Reporting PPM error measurement every 10 seconds... Press ^C after a few minutes. Reading samples in async mode... ERROR ns: 7791886 ERROR ns: 9259301 lost at least 185 bytes real sample rate: 2073369 real sample rate: 2048190 ^CSignal caught, exiting! User cancel, exiting... Cumulative PPM error: -289 The modifications to demonstrate the issue: nuno@ubuntu:~/Desktop/rtl-sdr/src$ git diff diff --git a/src/rtl_test.c b/src/rtl_test.c index f5a56b8..1935bfb 100644 --- a/src/rtl_test.c +++ b/src/rtl_test.c @@ -138,9 +138,11 @@ static void rtlsdr_callback(unsigned char *buf, uint32_t le ppm_now.tv_sec = tv.tv_sec; ppm_now.tv_nsec = tv.tv_usec*1000; #endif - if (ppm_now.tv_sec - ppm_recent.tv_sec > PPM_DURATION) { - ns = 1000000000L * (int64_t)(ppm_now.tv_sec - ppm_recent.tv_sec) - ns += (int64_t)(ppm_now.tv_nsec - ppm_recent.tv_nsec); + ns = 1000000000L * (int64_t)(ppm_now.tv_sec - ppm_recent.tv_sec); + ns += (int64_t)(ppm_now.tv_nsec - ppm_recent.tv_nsec); + if(ns<60000000) + printf("ERROR ns: %9lld\n",ns); + if (ppm_now.tv_sec - ppm_recent.tv_sec > PPM_DURATION) { printf("real sample rate: %i\n", (int)((1000000000L * ppm_count / 2L) / ns)); #ifndef __APPLE__ Nuno

1 0

Can't get below -46 dB
by Luca Bedogni 17 Apr '13

17 Apr '13

Hi I have an Elonics 4000 USB receiver, and I-m trying to do some measurements on the digital television received power in my area. Everything works fine, except that the received power is never lower than -46 dB, even on channel which are not occupied. I was expecting to get values like -120 dB or something similar, instead in my measurements the lowest point in any portion of the spectrum is circa -46 dB. Am I missing something? Thank you Best

3 3

DAB+ free/open encoder: fdk-aac-dabplus
by Benjamin Hagemann 16 Apr '13

16 Apr '13

Hello, I read on twitter: Opendigitalradio.org @opendigiradio "A new DAB+ free/open encoder is born ! https://github.com/piratfm/fdk-aac-dabplus …" https://twitter.com/opendigiradio/status/324231787163303936 -- Regards, Benny gpg 0xFC505AB0 jabber benny(a)benny.de sip benny(a)benny.de

4 3

Using the R820T above 1.77 GHz?
by Per Baekgaard 16 Apr '13

16 Apr '13

One more (but completely different) topic, hence a separate mail: Has anyone experimented with using the R820T above 1.77 GHz?

2 4

ask help for the format of outcome IQ data
by kainwen 16 Apr '13

16 Apr '13

Hello, I use rtl_sdr to collect some data into a bin file(file.bin). As from the wiki, I think it is parsed like this : /fd = open("file.bin","r") ;// // char I[];// // char Q[];// ////loop :// // read(fd, I, 1) ;// // read(fd, Q,1) ;// // endloop// // char *p = Q ;// // loop :// // printf("%f\n", (float*)p);// // p += 4 ;// ////endloop/ But this code can only print 0.00000 I don't know where the error is. Please help me. Thank you.

1 0

← Newer
1
...
68
69
70
71
72
73
74
...
91
Older →

Jump to page:

2025

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

osmocom-sdr