osmocom-sdr July 2013

osmocom-sdr@lists.osmocom.org

12 participants
15 discussions

rtl_tcp problem or not?
by Favati 25 Feb '14

25 Feb '14

Hi there! I'm using a dongle on a raspberry + rtl_tcp and sdrsharp on another machine (quad core.... 3gb ram...good machine!) The problem occour at 00:57 http://www.youtube.com/watch?v=4E2MPfEzEi8 and at 1:34 in this video: http://www.youtube.com/watch?v=8snz1wQSRpw If i stop and start sdrsharp, it works ok for some minutes...then the problem is up again! No errors appear on the console of raspberry/rtl_tcp I'm not able to understand if it's a problem of rtl_tcp,raspberry or whatelse... Things i've tryed: 1) Changed the samplerate 2) Changed the raspberry (tested tp1/tp2 too...getting 4.98v!!!) 3) Changed the dongle 4) Updated sdrsharp The dongles tryed work ok on a pc I've no more idea.... Anyone can help me? PS: If someone know a program that works in linux and is similar to sdrsharp AND CAN INTERFACE TO A REMOTE RTL_TCP...

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MiricsFlexiTV-MSI3101
by marzano 21 Nov '13

21 Nov '13

A quite good (AM/SW)/FM/DAB/DVB-T USB dongle. Mirics FlexiTV MSi3101 (two chips MSi001+MSi2500) http://www.mirics.com http://www.mirics.com/node/31 Data sheets available, register yourself at Mirics portal. RF Tuner: MSi001/MSi002 ( used by FUNcubrePro+ ?), seems better than R820T ADC and HiSpeed USB interface: MSi2500 . ADC 10 bit , better than 8 bit RTL2832U aDC. Windows binary software available: FMDABplayer, DVB_T decoder, Windows lib.dll and API doc. IO-DATA GV-TV100 stick sold on Japan . Stick, chips and dev board available from Mirics. Linux software at address http://cgit.osmocom.org/libmirisdr/ It seems project on stand-by . Can author Steve Markgraf comment ? Francesco

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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

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R820T vs. E4000
by Benedikt Heinz 09 Sep '13

09 Sep '13

Hi everyone, although there are some comparisons between the R820T and the E4000 already [1, 2], I also did some tests with another use-case in mind. I'm working on a thing similar to RTLSDR-Scanner [3]. I want to monitor a large part of the spectrum continuously. So I compared the R820T with the E4000 using RTLSDR-Scanner w/ and w/o an antenna. My results are here: https://docs.google.com/folder/d/0ByDAKwyEiyx_XzZ5ZnpRV1VZWDQ/edit?usp=shar… There's much more spurs with the E4000 than w/ the R820T. According to [1, 2] one also would expect a better overall sensivity compared to the E4000. However, the GSM900 signals for example seem to be way better with the E4000 according to the RTLSDR-Scanner. Tuning to a certain channel w/ OsmoSDR Source in GNUradio gives about the same SNR - contrary to the RTLSDR-Scanner output. Can anyone explain this? Also, the DVB-T channel at 502MHz is quite weak in the R820T RTLSDR-Scanner output when compared to the E4000. I had a closer look at the lower limit of the channel in gnuradio. This can be seen in the 502MHz_*.png pictures. The E4000 produces a nice +20dB step while one can hardly see the channel in the R820T spectrum. I don't understand this as well. Is this AGC-related? Manually setting a fixed gain didn't really help though... Any explanations? Thank you! Best regards, Hunz [1] http://steve-m.de/projects/rtl-sdr/tuner_comparison/ [2] http://www.hamradioscience.com/rtl2832u-r820t-vs-rtl2832u-e4000/#more-1852 [3] https://github.com/EarToEarOak/RTLSDR-Scanner

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OpenBSD: crashing
by Alan Corey 18 Aug '13

18 Aug '13

This is with a version of rtl-sdr I got by git last night and OpenBSD 5.2 (current release). 5.2 has some pthreads fixing so I waited until I bought another computer and loaded it. Are the crashes related to threads? I don't know, but possibly. It didn't work with OpenBSD 5.0 either. rtl_fm crashes and uses threads rtl_adsb crashes and uses threads rtl_tcp doesn't crash, uses threads, actually stops on ctrl-c rtl_test doesn't crash, doesn't use threads, won't stop rtl_eeprom doesn't crash, doesn't use threads, ends normally I'm not real practiced using gdb but I tried looking at a couple of core files, here's a run of rtl_fm: rtl_fm -f 162550000 -N - | play -t raw -r 24k -e signed-integer -b 16 -c 1 -V1 - -: (raw) Encoding: Signed PCM Channels: 1 @ 16-bit Samplerate: 24000Hz Replaygain: off Duration: unknown In:0.00% 00:00:00.00 [00:00:00.00] Out:0 [ | ] Clip:0 Found 1 device(s): 0: Realtek, RTL2838UHIDIR, SN: 00000013 Using device 0: ezcap USB 2.0 DVB-T/DAB/FM dongle Found Rafael Micro R820T tuner Oversampling input by: 42x. Oversampling output by: 1x. Buffer size: 8.13ms Tuned to 162802000 Hz. Sampling at 1008000 Hz. Output at 24000 Hz. Exact sample rate is: 1008000.009613 Hz Tuner gain set to automatic. In:0.00% 00:00:00.00 [00:00:00.00] Out:0 [ | ] Clip:0 Done. Abort (core dumped) d530# gdb -c rtl_fm.core /usr/local/bin/rtl_fm GNU gdb 6.3 Copyright 2004 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "i386-unknown-openbsd5.2"... Core was generated by `rtl_fm'. Program terminated with signal 6, Aborted. Reading symbols from /usr/lib/libpthread.so.16.0...done. Loaded symbols for /usr/lib/libpthread.so.16.0 Reading symbols from /usr/lib/libm.so.7.0...done. Loaded symbols for /usr/lib/libm.so.7.0 Reading symbols from /usr/local/lib/librtlsdr.so.0.0...done. Loaded symbols for /usr/local/lib/librtlsdr.so.0.0 Reading symbols from /usr/local/lib/libusb-1.0.so.1.0...done. Loaded symbols for /usr/local/lib/libusb-1.0.so.1.0 Symbols already loaded for /usr/lib/libpthread.so.16.0 Reading symbols from /usr/lib/libc.so.65.0...done. Loaded symbols for /usr/lib/libc.so.65.0 Loaded symbols for /usr/libexec/ld.so #0 0x0abbd98d in kill () from /usr/lib/libc.so.65.0 (gdb) bt #0 0x0abbd98d in kill () from /usr/lib/libc.so.65.0 #1 0x0ac29545 in abort () at /usr/src/lib/libc/stdlib/abort.c:68 #2 0x005e9298 in pthread_mutex_unlock (mutexp=0x3c003d8c) at /usr/src/lib/librthread/rthread_sync.c:218 #3 0x1c00266e in full_demod (fm=0xcfa2de5c) at /usr/src/misc/osmocom/2013-04-15/rtl-sdr/src/rtl_fm.c:583 #4 0x1c0028ff in demod_thread_fn (arg=0xcfa2de5c) at /usr/src/misc/osmocom/2013-04-15/rtl-sdr/src/rtl_fm.c:641 #5 0x005ebc2e in _rthread_start (v=0x84da4c00) at /usr/src/lib/librthread/rthread.c:111 #6 0x0aba62e9 in __tfork_thread () from /usr/lib/libc.so.65.0 The backtrace (bt) shows that it dies trying to do a mutex_unlock (I think). rtl_tcp also does a mutex_unlock and it doesn't crash. I'm probably reading it wrong for all I know. I don't know what's causing the signal 6 either. I'd also like to get the -lrt of of the cmake files. OpenBSD doesn't use or have lrt, it works without. I can edit it out and compile, but every time I run cmake again, I have to edit the files again. Alan ----- Radio Astronomy - the ultimate DX

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ACARS decoder using rtl-sdr
by Skip Tavakkolian 29 Jul '13

29 Jul '13

Hi, Thank you Thierry and Andreas for your work. I've been experimenting with rtl-sdr library with different RTL2832U devices -- initially for receiving/decoding ADS-B data, and now for ACARS data -- and have been very impressed by the device and the code. For ACARS I was on the same path -- i.e. merging Thierry's code with rtl_fm (AM mode) -- and I'm very happy to see Andreas has already done it! Incidentally, my plan for writing an ADS-B decoder was also (fortunately) shortened when I discovered Dump1090 (Salvatore Sanfilippo) and a nice fork of it (MalcolmRobb). To compile rtl_acars.c, I added it to my local rtl_sdr source directory and made a few mods to the CMakeLists.txt files, etc to build/install it. The diffs can be found here (includes my mods to CMakeLists.txt to compile on Mac OS X): http://pastebin.com/nwjtUDqC -Skip Thierry Leconte wrote: > Le 15/07/2013 09:54, Andreas Reinhardt a écrit : > > Hi everyone, > > > > I have combined "rtl_fm" with Thierry Leconte's (GPL'ed) acarsdec > library code and created "rtl_acars" which can directly decode ACARS flight > info messages to the console. > Hey that's great news! > I just bought a rtl card for fun recently and subscribe to this list . > Very happy to see someone use my very old acars decoder code :-) > will try it very soon !

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RTL_FM raw mode squelch
by Sdr Guru 29 Jul '13

29 Jul '13

Hi Please enable raw mode squelch. It does wonders when debuging remote loctions (ppm_error!). And significantly reduces data volumes. rtl_fm -R -f 1**M -s 12k -l 220 | sox -r 12k -t raw -e signed-integer -b 16 -c 2 -V1 - -C 0 out.flac sox out.flac out_s.wav silence -l 1 0.2 1% -1 2.0 1% SG

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Re: osmocom-sdr Digest, Vol 20, Issue 12
by Peter Stuge 29 Jul '13

29 Jul '13

Peter Dohm wrote: > I can show you screen shots of zadig if you'd like to see them, Even if they look good that's actually not good enough.

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Terratec T-Stick+ oddity in Windows 8
by Peter Dohm 29 Jul '13

29 Jul '13

Hi. As it appears, the Terratec T-Stick+ is supported properly in the latest releases of osmocom's libraries. I have a T-Stick+ working properly in SDRSharp using the latest version of the standard zadig drivers as everyone on Windows uses. When i downloaded the latest osmocom Windows binaries from here: http://sdr.osmocom.org/trac/attachment/wiki/rtl-sdr/RelWithDebInfo.zip, i get the following result when i run rtl_test.exe on a fully-patched Windows 8 64-bit OS: C:\Users\user\Downloads\RelWithDebInfo\rtl-sdr-release\x64>rtl_test.exe -t Found 2 device(s): 0: Terratec T Stick PLUS 1: Terratec T Stick PLUS Using device 0: Terratec T Stick PLUS usb_open error -12 Failed to open rtlsdr device #0. I've tried this both as administrator and as a normal user, btw. Curiously enough, HDSDR also can not locate the device for some reason no matter what I do, and i've installed the zadig drivers on BOTH tuner instances just to be sure... Somewhat perplexed... Can anyone offer any advice? Cheers Peter Dohm

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ACARS decoder using rtl-sdr
by Andreas Reinhardt 22 Jul '13

22 Jul '13

Hi everyone, I have combined "rtl_fm" with Thierry Leconte's (GPL'ed) acarsdec library code and created "rtl_acars" which can directly decode ACARS flight info messages to the console. Confirmed to compile on OSX 10.6 (not possible for me to check if it also compiles under Windows and *nix). Feel free to add it as another proof of concept to your distro unless you consider it too much of a quick&dirty hack. Grab the code from: http://pastebin.com/kLJHyQWt Best regards, Andreas

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osmocom-sdr July 2013