September 2013 - osmocom-sdr - lists.osmocom.org

Complex FIR and Stereo support for rtl_fm
by Miroslav Slugeň 12 Nov '14

12 Nov '14

Hi again, I am working on my own SDR project for Stereo FM radio support, but i would like to also improve quality for rtl_fm application, i made unoficial patch to add: Complex FIR - to filter strong signals close to wanted signal Real FIR - to filter pilot from FM Stereo FIR Stereo Deemphasis AGC support - it can give better resolution of IQ data Some other improvments in FM radio code. All FIR filters has 3 possible variants, simple, LUT, SSE2 instricts, of course SSE is the fastest one and it should works on Intel Atoms, but not on ARM. Feel free to use any part of code in any of you programs, I know that this code is little to much to add it into rtl_fm, but maybe it could somebody help to recieve HW stereo FM radio. Speed of SSE code is much better than anything you can get around here, on Core i7 it consume only 5% of one CPU, so i could demodulate at least 80 channels at the same time in stereo quality of course. I tried this code only on AMD64 and GCC Linux, so i am not sure if it can be compiled under windows. -- Miroslav Slugeň +420 724 825 885 Teramos Multimedia s.r.o.

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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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How to get IQ samples from multiple rtl-sdr dongles in a synchronized manner?
by Jiao Xianjun 02 Jan '14

02 Jan '14

Hi, I want to use multiple rtl-sdr dongles to do some multi-antenna experiments. Is it possible to read IQ samples from multiple rtl-sdr dongles in a synchronized manner? I already have a glance at dump1090 codes, which is a project using rtl-sdr to decode aircraft broadcasting ADS-B messages in 1090MHz. Seems that I should use rtlsdr_read_async() instead of rtlsdr_read_sync(), because that if rtlsdr_read_sync() is used, I have to call it multiple times sequentially. That looks not synchronized. But rtlsdr_read_async() function only accept one rtl-sdr device as input parameter, and it will be blocked after it is called. So seems that it also can't be used for my purpose directly. Also welcome any opinion on how to improve rtl-sdr lib/driver to support this feature. Thank you. BR Jiao Xianjun

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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_? 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

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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

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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

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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 :-(

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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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