osmocom-sdr

osmocom-sdr@lists.osmocom.org

904 discussions

None
by Alessandro Staniscia 08 Oct '13

08 Oct '13

Hi all, I have built my antenna and now I wont evaluate my work, so, in your opinions can I use the rtl_sdr software to accomplish it? Someone have a suggestion or is it impossible? Thanks

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Runtime Error
by Sohaib Khan 01 Oct '13

01 Oct '13

i have captured a file (FM file), using rtlsdr2832u.... i.e cap.bin. How can i play it or open it??? Kindly help Sohaib Bin Altaf Pakistan

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Runtime:error
by Sohaib Khan 01 Oct '13

01 Oct '13

I am using DVB-T dongle RTLSDR2832U with gnu radio, i have installed all the required files, but when i compile my flowgraph I get an error. Runtime Error:Failed to open rtlsdr device. What is the problem and its solution?? I cannot install udev rules also, i also face errors at it.... should i uninstall my ubuntu and start from the very begining. Sohaib bin Altaf pakistan

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rtl_? for radio control?
by Alan Corey 27 Sep '13

27 Sep '13

OK, so you plug a $20 dongle into a Raspberry Pi, hook some stuff to the GPIO connector and with probably minor tweaks to something like RTL_FM you can use it as a radio in radio-controlled model planes, cars, boats. Add the Pi's $25 camera and you could have a radio-controlled camera, useful for sending up in a radio-controlled plane or doing wildlife photography. If you've got some analog (pulse position) channels those would be good for rudder, flaps, various camera settings. This can be done in the 27 MHz CB band or with a ham license in something like the 6 meter ham band. I had no trouble getting RTL_FM running on my Pi but it probably doesn't have enough CPU horsepower to do a lot of processing on the dongle side and on the imaging side at the same time. Anybody done this? Alan ----- Radio Astronomy - the ultimate DX

1 0

LIBUSB_ERROR_PIPE?
by Gisle Vanem 25 Sep '13

25 Sep '13

Since my last Windows Update (not sure that's the cause), I'm having a hell to regain access to my Terratec DVB-Tstick with ther Elonics E4000 tuner. I've modified librtlsrc.c to include some more traces and relinked rtl_test with it. All I'm getting is LIBUSB_ERROR_PIPE trying to read/write the I2C-bus: Osmocom-SDR\src\rtl_test.exe Found 1 device(s): 0: Terratec T Stick PLUS Using device 0: Terratec T Stick PLUS librtlsdr.c(392): I2C addr C8: got 00, rd_len: -9, wr_len: -9 librtlsdr.c(394): Read error: LIBUSB_ERROR_PIPE, Pipe error librtlsdr.c(396): Write error: LIBUSB_ERROR_PIPE, Pipe error librtlsdr.c(392): I2C addr C6: got 00, rd_len: -9, wr_len: -9 ... No supported tuner found Enabled direct sampling mode, input 1 Supported gain values (1): 0.0 ---------------- What could be the reason for this? What else should I try? --gv

12 34

LabVIEW support for rtl_tcp
by András Retzler 25 Sep '13

25 Sep '13

Hi, I've made some SubVIs for LabVIEW to support rtl_tcp. http://ha5kfu.sch.bme.hu/sites/default/files/public/sdrlab-rtl_tcp-interfac… I hope that someone will find it useful. More information and screenshot: http://ha5kfu.sch.bme.hu/sdrlab -- I'd like to say thanks for your work on the RTL-SDR project, it's something really cool :-) Regards, András Retzler HA7ILM

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gr-iqbalance documentation build problem
by wk＠ire.pw.edu.pl 19 Sep '13

19 Sep '13

Hello. I have some build problem with building gr-igbalance with documentation enabled. Build fails with a message saying that shell interpreter can't execute Doxyfile. It is the same as I noticed some time ago while building gr-osmosdr (see http://lists.osmocom.org/pipermail/osmocom-sdr/2013-April/000553.html ). It was solved by the patch by Jaroslav Škarvada ( http://cgit.osmocom.org/gr-osmosdr/commit/?id=2f6592566bd60d2539f5b976dcf61… ). Similar patch, attached, help for gr-iqbalance. It moves doxygen detection test to toplevel CMakeLists.txt. Please add it to git repository. Wojciech Kazubski

2 1

rtl_fm and multimon-ng issues
by Ewan Meadows 19 Sep '13

19 Sep '13

Hi all, I've been using rtl_fm piped into multimon-ng for a while now which has been working pretty well for decoding POCSAG, I use this command line: rtl_fm -f 153.350M -r 22050 - | ./multimon-ng -t raw -a POCSAG512 -a POCSAG1200 -a POCSAG2400 -f alpha -D pocsag.db - I updated rtl_sdr today and now all I get is junk decodes POCSAG2400-: Address: 1318769 Function: 255 POCSAG2400-: Alpha: KA^MA POCSAG1200-: Address: 1700218 Function: 255 POCSAG1200-: Alpha: )"<DLE>'f POCSAG1200-: Address: 143961 Function: 255 I rolled back to an earlier version using git checkout commit and it appears the following commit broke it: c4fcfbb46e0a432902a2b78db4951bd20f68b9b2 Commit 8c3a99c8f7a88d7d2a05845d4b20cfcdacac4054 works fine, whereas the commit after causes multimon_ng to spit out garbage :-(

2 3

rtl-sdr offset tuning and other questions
by David Jacobowitz 19 Sep '13

19 Sep '13

Hi guys, I'm new to this list (and to radio) so I hope you will please indulge me if I ask something that is a FAQ. Also, some of these questions are about the dongle, not the library. I am working on a personal project to use SDR techniques to decode aviation navigation signals (VOR). I've got the signal processing mostly working from recorded signals, but am now trying to integrate my SW with the radio in real time. I have a few questions: - What exactly is offset tuning? How is offset tuning different from tuning to an offset? Is this a feature that mostly benefits people who are not going to put their IF through another mixer? In my application I am already tuning to an offset, and pulling down a wide enough IF that actually holds many channels of interest. (VOR channels have 50kHz spacing). I then use a software mixer/channelizer to choose the channel I want. Am I correct in assuming that offset tuning is of no use to me? - regarding AGC, what is the difference between AGC and auto gain? That is, the library API has RTLSDR_API int rtlsdr_set_tuner_gain_mode(rtlsdr_dev_t *dev, int manual) RTLSDR_API int rtlsdr_set_agc_mode(rtlsdr_dev_t *dev, int on); I'm guessing that these affect different AGCs. One for the tuner and one for the RTL device. What are the benefits and costs of having either or both on? - regarding rtlsdr_read_async(...) and related functions. I take it that the library is setting up a ring buffer and calling me back when it has a new buffer of data for me. How long to I have to work with this buffer? Obviously, if I want to work in real-time I need to keep up with the sample rate. But my application can afford to throw away buffers since it can decode a few ms of data from one station and then revisit it much later. However, I'd like to know how long I have until the buffer gets clobbered. I'm presuming it's stable until all the n-1 other buffers have been hit. - generally how fast can the RTL devices tune? I know, this is not an rtlsdr question per se, but I'm curious. I noticed that when I tune, I get a delay. This is a great library and I'm so glad it's out there! I was not looking forward to plumbing the depths of USB drivers to understand how to pull data from the RTL dongle! I think rtl-sdr.h could use perhaps a smidge more documentation. I'd be happy to submit a comments-only patch if there's interest. :-) Regards, Dave Jacobowitz

4 5

[PATCH] rtl_sdr: Direct sampling mode + RTL AGC
by psb hlw 15 Sep '13

15 Sep '13

Hi, I didn't find rtl_sdr with implemented direct sampling mode, so I made the patch. Also it has an option to set RTL AGC on. This feature allows to use tuners as cheap data loggers without changing the schematic of the tuners. You can just connect wires directly to pins 1-2 of RTL2832 (I channel, diff. input) or pins 3-4 (Q channel, diff. input). When direct sampling mode is on - tuner's chip outputs are disabled and doesn't affect external signal. For example, this command will write 8 bit samples to file 'mydata' at 2.4 MHz sampling rate with automatic gain: rtl_sdr.exe -f 0 -s 2400000 -i -G mydata Hope this will be useful for somebody as it was for me. If you will accept the patch - please, update the windows binaries. Thanks, psb. ------------------------------------------------------------------------------- diff --git a/src/rtl_sdr.c b/src/rtl_sdr.c index eeb6dba..3564329 100644 --- a/src/rtl_sdr.c +++ b/src/rtl_sdr.c @@ -42,6 +42,7 @@ static int do_exit = 0; static uint32_t bytes_to_read = 0; static rtlsdr_dev_t *dev = NULL; +static int samp_mode = 0; void usage(void) { @@ -54,6 +55,9 @@ void usage(void) "\t[-b output_block_size (default: 16 * 16384)]\n" "\t[-n number of samples to read (default: 0, infinite)]\n" "\t[-S force sync output (default: async)]\n" + "\t[-i set direct sampling mode (I)]\n" + "\t[-q set direct sampling mode (Q)]\n" + "\t[-G use RTL automatic gain]\n" "\tfilename (a '-' dumps samples to stdout)\n\n"); exit(1); } @@ -81,6 +85,8 @@ static void sighandler(int signum) static void rtlsdr_callback(unsigned char *buf, uint32_t len, void *ctx) { + uint32_t i, r; + unsigned char *p1, *p2; if (ctx) { if (do_exit) return; @@ -91,7 +97,16 @@ static void rtlsdr_callback(unsigned char *buf, uint32_t len, void *ctx) rtlsdr_cancel_async(dev); } - if (fwrite(buf, 1, len, (FILE*)ctx) != len) { + if (samp_mode) { + // For direct sampling mode we throw out each 2nd value, + // i.e., save only one channel data - I or Q. + for (i=0, p1=buf, p2=buf; i<len; i+=2, p2++) + *p1++ = *p2++; + r = (fwrite(buf, 1, len/2, (FILE*)ctx) == len/2); + } else + r = (fwrite(buf, 1, len, (FILE*)ctx) == len); + + if (!r) { fprintf(stderr, "Short write, samples lost, exiting!\n"); rtlsdr_cancel_async(dev); } @@ -119,8 +134,10 @@ int main(int argc, char **argv) uint32_t out_block_size = DEFAULT_BUF_LENGTH; int device_count; char vendor[256], product[256], serial[256]; + uint32_t use_rtlagc = 0; + unsigned char *p1, *p2; - while ((opt = getopt(argc, argv, "d:f:g:s:b:n:S::")) != -1) { + while ((opt = getopt(argc, argv, "d:f:g:s:b:n:S::Gqi")) != -1) { switch (opt) { case 'd': dev_index = atoi(optarg); @@ -143,6 +160,15 @@ int main(int argc, char **argv) case 'S': sync_mode = 1; break; + case 'q': + samp_mode = 2; + break; + case 'i': + samp_mode = 1; + break; + case 'G': + use_rtlagc = 1; + break; default: usage(); break; @@ -205,6 +231,15 @@ int main(int argc, char **argv) if (r < 0) fprintf(stderr, "WARNING: Failed to set sample rate.\n"); + /* Set direct sampling */ + if (samp_mode) { + r = rtlsdr_set_direct_sampling(dev, samp_mode); + if (r < 0) + fprintf(stderr, "WARNING: Failed to set direct sampling mode.\n"); + else + fprintf(stderr, "Tuner set to direct sampling mode (%c).\n", (samp_mode==1)?'I':'Q'); + } + /* Set the frequency */ r = rtlsdr_set_center_freq(dev, frequency); if (r < 0) @@ -231,6 +266,21 @@ int main(int argc, char **argv) fprintf(stderr, "Tuner gain set to %f dB.\n", gain/10.0); } + /* Set RTL automatic gain */ + if (1 == use_rtlagc) { + /* Enable automatic RTL gain */ + r = rtlsdr_set_agc_mode(dev, 1); + if (r < 0) + fprintf(stderr, "WARNING: Failed to enable RTL automatic gain.\n"); + else + fprintf(stderr, "RTL automatic gain enabled.\n"); + } else { + /* Disable automatic RTL gain */ + r = rtlsdr_set_agc_mode(dev, 0); + if (r < 0) + fprintf(stderr, "WARNING: Failed to disable RTL automatic gain.\n"); + } + if(strcmp(filename, "-") == 0) { /* Write samples to stdout */ file = stdout; #ifdef _WIN32 @@ -263,7 +313,16 @@ int main(int argc, char **argv) do_exit = 1; } - if (fwrite(buffer, 1, n_read, file) != (size_t)n_read) { + if (samp_mode) { + // For direct sampling mode we throw out each 2nd value, + // i.e., save only one channel data - I or Q. + for (i=0, p1=buffer, p2=buffer; i<n_read; i+=2, p2++) + *p1++ = *p2++; + r = (fwrite(buffer, 1, n_read/2, file)== n_read/2); + } else + r = (fwrite(buffer, 1, n_read, file) == n_read); + + if (!r) { fprintf(stderr, "Short write, samples lost, exiting!\n"); break; }

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