osmocom-sdr April 2012

osmocom-sdr@lists.osmocom.org

19 participants
13 discussions

by Michal Demin

Hello, Attached are 2 patches: 1 - Try to detach kernel driver from device, when kernel driver present. 2 - add rtl_tcp binary to gitignore. Michal Demin

12 years

RTL-SDR ghost signal at center frequency & hangs in GR spectrum view

by Benedikt Heinz

Hi everyone, can someone explain to me, what the origin of the ghost signal close to center frequency is? It can be seen at [1] and [2] - both are EzTV668 with no antenna connected. It seems to me, that the higher the frequency, the more one can see the "burst-like" nature of this signal. Is this some mixer artefact from the E4k tuner? The best workaround is probably tuning a bit off the actual target frequency and using frequency xlate? Also, in [3] (german) the blind spot at 0Hz due to the coupling capacitors between E4k & RTL is mentioned. Is it possible to replace the capacitors with 0-Ohm resistors to work around this issue, or will this cause other unwanted side-effects? Or does this make no sense at all since one should always tune a bit off and use xlate due to the ghost signal? I guess it should also be possible (w/ some hot glue & wires) to insert some jumpers (like OsmoSDR) instead, so one can use the ADCs directly for LF/MF with some extra analog stuff? Regarding the OsmoSDR source - I also gave the RTL-source from gr-baz a try and noticed, that with averaging enabled in the spectrum view in GR, the top-block GUI usually won't react to user input any longer when using OsmoSDR, but this doesn't happen with the gr-baz RTL source, although I used the same sample rate in both cases. Does anyone understand why it doesn't hang with the gr-baz source? Thanks for your answers! Regards, hunz [1] http://hackdaworld.org/~hunz/rtl-sdr/wo_ant_2m_osmo.png [2] http://hackdaworld.org/~hunz/rtl-sdr/wo_ant_70cm_osmo.png [3] http://www.mikrocontroller.net/topic/253371#2610540 -- Benedikt Heinz hunz(a)jabber.berlin.ccc.de

12 years, 1 month

OsmoSDR - they're on final approach

by Christian Daniel -- maintech GmbH

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi everybody, just as a short heads up: The new boards have arrived and the first batch of 20 is assembled. Since we did changes to the layout we will verify them before we do the other 80. This should take no more than a few days. Stay tuned! BTW: The new pre-amp/lnb really does add 18dB :) Best regards, Christian - -- - --------------------------------------------------- | maintech # Dipl. Inf (FH) Christian Daniel | | GmbH ### Otto-Hahn-Str. 15 · D-97204 Höchberg | - --------------------------------------------------- | AG Würzburg, HRB 8790 Tax-ID DE242279645 | - --------------------------------------------------- | http://www.maintech.de cd(a)maintech.de | - --------------------------------------------------- -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJPkBrEAAoJEHkgzUIsAWritBgH/RqDZuLRLQ/22msTdvZ+EIqk 6Y98xDBrDcXSkTSsFBQvLwdKANUxxi3dVvTjknBw3lnrWzT8fo2uVMg97c/R6Eov fGOvALbXckgrmvz0n/IZdROu8x38zs/ro0uweN0oxb14+U/2CW5VVeJusqcQoBL6 Ug4XAtzXpyR04pmjjq6jzxtsmsXuv42KToG7R9UvkiNz8WXhxlaaUmA+ccJGM+8+ FCITzYY9ZMfFo2IekXDGkZNsKwux37B8cQxYIlcSlPxlSrPzusFyyqEq2AmM1iIn SbuRnmjzeUQbsgGVINmVP1B3EDOczeYWyeKC/5myXbr+Ogpp9/PD9K9aJG/sKYM= =KY1W -----END PGP SIGNATURE-----

12 years, 1 month

Real-time DRM+ receiver chain using the NOXON stick

by Feilen, Michael

Dear Osmocon-SDR People, Thank you so much for providing the information on the RTL-SDR USB sticks on your webpage! I've used the stick to get a DRM+ receiver implementation running and the stick seems to work quite well: http://www.youtube.com/watch?v=zeGs7CQlvRg I've had to twiddle around with the tuner parameters of the FC0013 to get it running stable. However, I've never reached more than 25 dB SNR for the in-band OFDM signal (which has a bw of 100 kHz and I'm resampling from 1 MS/s to 120 kS/s). I wonder if the tuner is the limiting factor or the RTL chip. With a resolution of 8 bit, I would have expected more. Hmm, maybe it's the phase noise of the tuner or the IQ correction routines of the RTL chip? Has anybody of you guys a meaningful measure for the quality of the different tuners for the RTL stick? I know that the E4000 supports a higher bandwidth but does it provide a better IQ signal with less distortion? Cheers, Michael

12 years, 1 month

rtl-sdr with Compro Videomate U620F

by Simeon Miteff

Hi All The Compro Videomate U620F has the magic RTL2832+E4000 combination. rtl-sdr recognises it with the patch: https://gist.github.com/2362895 Regards, Simeon.

12 years, 1 month

Buffer length in rtlsdr_wait_async

by Andrea Montefusco

Hi all, together with Oliver DL6KBG (that really provides me with all the hardware needed, thanks !), we are attempting to write a server suitable for use with ghpsdr3-alex SDR software. A first attempt using the a home built code was quite successfully, albeit some defect is yet there. Now we are trying to use the librtlsdr: first off, many thanks to developers. We are stucked into rtlsdr_wait_async that is using a fixed quite large buffer, as per #define BUF_LENGTH (16 * 16384) now that is quite inconvenient in ghpsdr3-alex, because, at low sample rate (250000) we use, we are unable to cope with the large delay that this large buffer introduces. So, just as crude workaround, we simply patched the value into the lib. What would be ideal is an additional parameter in rtlsdr_wait_async that allow us to reduce the buffer to a more suitable size for our needs. Thanks in advance *am* --------------------------------------------------------- Andrea Montefusco iw0hdv http://www.montefusco.com tel: +393356992791 fax: +390623318709 ---------------------------------------------------------

12 years, 1 month

Tuner performance for rtl-sdr

by Mathias Coinchon

Hi, Does anybody have some hints, experiences on the performance difference (filtering, sensitivity, IQ imbalance, DC offset,..) between fc0012, fc0013 and e4000 tuners ? I could not get my hands on an e4000 yet but just fc0012 and fc0013. On FM band I see quite a number of mirror images from strong signals. Mathias

12 years, 1 month

Re: rtl-sdr with airprobe

by schwandre＠gmx.net

> I'd like to know what was the reasoning behind that statement ? > To me it shows a deep lack of understanding on how that script works ... the reason for this statement was, that i read somewhere, that the example-file was recorded with 1,8 MS/s and decimation of 174. yes, you are right, i don't know how that script works, i read the sources and understood maybe 5% of it, because this is all really new for me, as i am not a professional and my last programm i wrote, was for the 6510 about 20 years ago.... now i did some more readings and found, that to have needed bandwith of 200 khz with 1,8 MS/s is a decimation rate of 9 ? decimation=MS/bw ? guess i have to read a lot more, thanks for your info! -- NEU: FreePhone 3-fach-Flat mit kostenlosem Smartphone! Jetzt informieren: http://mobile.1und1.de/?ac=OM.PW.PW003K20328T7073a

12 years, 1 month

[PATCH] Fix FC0012 tuner filters for librtlsdr

by David Basden

Thanks to Steve for finding the bug in my GPIO code. This patch should have the FC0012 using it's VHF/UHF filters correctly. The difference in the UHF band is pretty stunning: http://imgur.com/a/gEutK Cheers, David David Basden (1): Correctly switch UHF and VHF filters for FC0012 include/tuner_fc0012.h | 3 +++ src/rtl-sdr.c | 8 +++++++- 2 files changed, 10 insertions(+), 1 deletion(-) -- 1.7.9.5

12 years, 1 month

librtlsdr - Terratec Cinergy T Stick Black (rev 1) works

by Oliver Goldenstein

Please add: { 0x0ccd, 0x00a9, "Terratec Cinergy T Stick Black (rev 1)" }, just tested with gnuradio. lsusb shows this: Bus 002 Device 005: ID 0ccd:00a9 TerraTec Electronic GmbH RTL2838 DVB-T COFDM Demodulator [TerraTec Cinergy T Stick Black] Works good. Stick uses rtl2832u/fc0012 -- Oliver, DL6KBG, JO61UB Blog: http://dl6kbg.blogspot.com

12 years, 1 month

rtl-sdr with airprobe

by schwandre＠gmx.net

Hi! I tried to use the recorded capture.bin of several arfcn with aiprobe. Checked the arfcn before with cell-log of osmocom. I converted the capture.bin to the cfile format with the rtl2832-cfile gnuradio block. checked the converted recordings with fft-gui of gnuradio. Seems to be fine. Now i used gsm-receiver with the follwing option to decode the broadcast traffic that is in ts0: GSM/airprobe/gsm-receiver/src/python$ ./go_usrp2.sh capture.cfile 174 0b with the downloaded samplefile of srlabs it works fine, but with mine not. i also tried to change the dezimation rate, did not help. i recorded the bin file with 1.8MS/s also did some tests with 200kS/s. How do i calculate the dezimation rate for the different MS/s ? I think it should work when i use 1.8MS/s and decimation rate of 174. What i am doing wrong? I am using the Hama Nano and the terratec noxon, both are working fine, tested it on radio-broadcast 88-108 MHz and 433 MHz ISM-Band. Will be thankful for any hint. Bye! -- Empfehlen Sie GMX DSL Ihren Freunden und Bekannten und wir belohnen Sie mit bis zu 50,- Euro! https://freundschaftswerbung.gmx.de

12 years, 1 month

Si5170 replaceable with SI514 ????

by Heikki Ylipiessa

Hi. I know that the Si570 is high precision oscilator ... And it mainly covers the frequencies quite well . But .. the 10MHz lower limit cuts the possibility of using it for 1.8MHz and 3.6Mhz and 7.0 MHz HAM radio bands ... The SI514 would possibly cover the need .. As I don't know how solidly the design has been made ... I'm asking if the Si570 can be replaced with SI514 and if so does the device firmware also need adjusting ??? -- Regards , Heikki Ylipiessa Home: heikki(a)ylipiessa.fi Work: heikki.ylipiessa(a)fi.ibm.com

12 years, 1 month

RTL-SDR: E4000 IF bandwidth

by Michał Rogala

Hi! I've just noticed one issue about E4000 driver that bothers me - IF bandwidth at the chip is set to 8 MHz, where maximum bandwidth of RTL2832U sampling is 3.2 MHz. Wouldn't reducing IF bandwidth at tuner chip improve overall sensitivity (and maybe noise level)? best regards Michal Rogala

12 years, 1 month

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osmocom-sdr April 2012