osmocom-sdr

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917 discussions

Buffer length in rtlsdr_wait_async
by Andrea Montefusco 08 Apr '12

08 Apr '12

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 ---------------------------------------------------------

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Tuner performance for rtl-sdr
by Mathias Coinchon 05 Apr '12

05 Apr '12

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

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Re: rtl-sdr with airprobe
by schwandre＠gmx.net 02 Apr '12

02 Apr '12

> 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

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[PATCH] Fix FC0012 tuner filters for librtlsdr
by David Basden 02 Apr '12

02 Apr '12

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

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librtlsdr - Terratec Cinergy T Stick Black (rev 1) works
by Oliver Goldenstein 02 Apr '12

02 Apr '12

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

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rtl-sdr with airprobe
by schwandre＠gmx.net 02 Apr '12

02 Apr '12

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

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Si5170 replaceable with SI514 ????
by Heikki Ylipiessa 02 Apr '12

02 Apr '12

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

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RTL-SDR: E4000 IF bandwidth
by Michał Rogala 01 Apr '12

01 Apr '12

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

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RTL2832 GNU Radio Source block now in gr-baz
by Balint Seeber 31 Mar '12

31 Mar '12

Hi folks, I've just added RTL2832 support to gr-baz <http://wiki.spench.net/wiki/Gr-baz> with support for both tuners (Elonics E4000 and Fitipower FC0013). I've taken rtl-sdr <http://sdr.osmocom.org/trac/wiki/rtl-sdr> and created a fully-featured GNU Radio Source block <http://wiki.spench.net/wiki/Gr-baz#rtl_source_c> 'baz.rtl_source_c' (with GRC block) that outputs complex values, and allows adjustment of frequency, sample rate and LNA gain. There is also an optional automatic tuner mode control for the E4000. The Source block performs internal multi-threaded buffering for smoother performance (this might be over-engineered, but it seemed to help with the ExtIO plugin <http://wiki.spench.net/wiki/USRP_Interfaces> I mentioned in my previous post here). You can get the source code from my SVN <http://svn.spench.net/main/gr-baz/> or github <https://github.com/balint256/gr-baz> (though please visit the info page <http://wiki.spench.net/wiki/Gr-baz#rtl_source_c> first for more info/pre-reqs - e.g. libusb-1.0, etc). It's experimental, and not the prettiest because I actually ported it back from the ExtIO plugin, but it works for me and if you want to help test/clean it up then that would be very much appreciated! To see it in action, have a peek here: http://youtu.be/FUQd9HOVTk8 Balint @spenchdotnet <http://twitter.com/spenchdotnet>

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RTL2832 SDR plugin for HDSDR/etc
by Balint Seeber 29 Mar '12

29 Mar '12

Hi folks, 'rtl-sdr' is a great development. Thank you to all involved! I'd like to throw in my bit: I've just released a beta version of my ExtIO plugin <http://wiki.spench.net/wiki/ExtIO_USRP> with support for RTL2832+E4000 (my one is called 'ezcap'). This means you can use the DVB-T USB stick with Winrad <http://www.winrad.org/> /HDSDR <http://www.hdsdr.de/> /WRplus, etc. http://spench.net/r/USRP_Interfaces I've done a fair bit of work <http://wiki.spench.net/wiki/RF> in GNU Radio, but I find having a simple/functional 'software specan' (i.e. those apps) is another great test tool. The ExtIO plugin also lets you stream the received baseband data from the app to GNU Radio over your LAN (just use the UDP Source block!). Apart from RTL2832, the plugin also supports all USRPs, the FUNcube Dongle, and functions as a network client if you choose to connect your SDR hardware to a separate computer and wish to stream the data & control the radio across your LAN (lossless, compared to having to use a long length of coax!). This protocol/implementation is called BorIP <http://wiki.spench.net/wiki/BorIP> , and is essentially a transparent network abstraction for the SDR receivers mentioned above (not really necessary if you have a LAN-enabled USRP, but great for USRP 1 & B100). The BorIP server is included with the plugin's installer. Additionally, I recently released many new blocks (in the gr-baz <http://wiki.spench.net/wiki/Gr-baz> module) and patches <http://wiki.spench.net/wiki/GNU_Radio_Patches> for GNU Radio too, part of which enables native BorIP reception support in GNU Radio (BorIP Source block, and BorIP protocol/packet support for UDP Source Block). The enhanced Source blocks are handy because they will notify you of hardware/buffer overruns at the server and network packet loss. Other new blocks help with automatic FEC decoding, and also include Variable Delay (great for blind signal analysis), a simple eye diagram sink (originally from OP25 <http://op25.osmocom.org/> ) and a Fast Auto-correlation Sink <http://wiki.spench.net/wiki/Fast_Auto-correlation> (originally from 'Frank'). I'm probably going to add my own implementation of a native RTL2832 Source block to gr-baz tonight, so I may post again soon. Hope this is useful! Kind regards, Balint @spenchdotnet <http://twitter.com/spenchdotnet>

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