osmocom-sdr

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906 discussions

Regarding Supported RTL-SDR hardware with GNU Radio
by reen erin 20 Nov '16

20 Nov '16

Hello I'm wondering if the Nooelec R820T SDR & DVB-T NESDR Mini is compatible with the GNU Radio Companion? I've tried using the osmocom and the rtl-sdr as the source but both didn't work. What happen is that i get "aUaUaU.." on the output box. Thank you, Reen

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direct sampling with RTL2832U
by friedtj＠free.fr 14 Nov '16

14 Nov '16

Following my recent inquiry about direct sampling using the newer RTL2832U+R820T(2) DVB-T receivers: 1/ I know from past experience that the E4k based dongles work fine in direct sampling. Since the E4k is zero-IF, I could just get rid of the I+/I- or Q+/Q- capacitors and feed the RTL2832U with the signal I want to sample. This works fine. 2/ The proposed patch I got last week aimed at canceling the IF frequency since R820T(2) receivers are not zero-IF. Here I was failing to get any result. Going back to basics, I realized that using my old E4k in direct sampling mode (rtl=0,direct_samp=1 in Gnuradio-companion osmosdr source) is also not working. This is an unexpected behavior since E4k based dongle configuration should not change whether direct sampling is used or not. Indeed using the same dongle *without* the direct_samp option did generate the right results. I tried yesterday hacking librtlsdr in an ugly way to get raw samples from the 820T(2) based receiver (solving my short term concern of getting data). I could indeed acquire relevant raw samples by getting librtlsdr to believe I was using a E4k dongle by replacing line 1580 of librtlsdr.c (right after the "found:" label) with dev->tuner_type=RTLSDR_TUNER_E4000; now this induces a change in all the init functions with the function pointers just defined afterwards (&tuners[dev->tuner_type];). I have not yet tracked the difference between the init functions, but I think it would be more or less safe to jump to the E4k code in case the direct_samp option is given. JM -- JM Friedt, FEMTO-ST Time & Frequency/SENSeOR, 26 rue de l'Epitaphe, 25000 Besancon, France

1 0

r820t2 based receiver raw samples ?
by Jean-Michel FRIEDT 12 Nov '16

12 Nov '16

I am attempting to use a RTL2832U based DVB-T dongle as a "fast" ADC for recording baseband signals. gr-osmosdr under GNURadio 3.7 (as provided by Debian GNU/Linux) provides the expected samples when using an E4000 (zero IF) dongle. Being obsolete, such a dongle is no longer relevant, and I want to do the same with the (non-zero IF) R820T(2) dongles. From http://sdr.osmocom.org/trac/wiki/GrOsmoSDR I should be able to use the direct_samp=1|2 option, but that does not work. I kept pins 1 and 2 connected to the R820T output and connected a wire to pin 5 (Q-) while Q+ (pin 4) is short circuited to pin 3 (gnd). A signal generator outputs a periodic signal (150 mV amplitude, 100 kHz) but still no baseband signal, and on the FFT of the osmosdr output I still see the spectrum of the FM band when tuning to 100 MHz rather than the samples from the (initially unconnected) Q input. Any idea if the "Device Arguments" of osmosdr-source is actually parsed and interpreted ? or is there a command line way of acquiring the raw baseband I/Q data ? Thanks, JM -- JM Friedt, FEMTO-ST Time & Frequency/SENSeOR, 26 rue de l'Epitaphe, 25000 Besancon, France ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.

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[PATCH] hackrf: fix buffer underflow
by P 28 Oct '16

28 Oct '16

Hi, lib/hackrf/hackrf_source_c.cc | 29 +++++++++++++++++------------ 1 file changed, 17 insertions(+), 12 deletions(-) this patch fixes SIGSEG wich happens when buffer from GnuRadio is bigger than buffers used by HackFR. This is due to 'remaining' will become bigger than size of input buffer. More than available bytes might be copied and '_samp_avail' become negative. This soon or latter becomes SIGSEG. With best regards, P

1 0

Fix for Airspy MIXER gain
by Lucas Teske 26 Oct '16

26 Oct '16

So I was having a problem with my GOES LRIT receiver in GNU Radio. In GQRX the SNR was 7dB and in GNU Radio was 4dB regardless of the setting. Then I noticed that the Mixer (BB Gain) wasn't working at all. Checked over the internet and there was this issue: So I made some changes and here is the working version: https://github.com/osmocom/gr-osmosdr/pull/8 (I know its a mirror, but the patch is also attached) Lucas Teske

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Installation error
by Ashish Kurian 06 Oct '16

06 Oct '16

Hi All, I downloaded the tar ball release libgtpnl-1.0.1.tar.gz and un tared it. Then I tried to build and install the package. But the command sudo ./configure is giving me the following error. configure: error: cannot find install-sh, install.sh, or shtool in build-aux "."/build-aux Do you know what could be the reason for this error? Best Regards, Ashish Kurian

2 1

Re: Moving from trac to a single redmine
by Harald Welte 26 Sep '16

26 Sep '16

On Sun, Sep 25, 2016 at 05:54:10PM +0200, Neels Hofmeyr wrote: > On Sat, Sep 24, 2016 at 08:01:52AM -0600, Sylvain Munaut wrote: > > I've just put this in place for 'openbsc.osmocom.org' : > > > > rewrite ^/trac/wiki/(.*)/(.*)$ > > $scheme://osmocom.org/projects/openbsc/wiki/$1$2 redirect; > > rewrite ^/trac/wiki(.*)$ $scheme://osmocom.org/projects/openbsc/wiki$1 redirect; > > But so far the idea is to keep the trac online and browsable, right? the main problem is that search engines still primarily seem to index + link to the old trac instances. So we were keeping that alive for some time. However, as the content is going out of date, and people still show an interest in editing the old content, I think we need to switch the trac off soon and replace it with links to the redmine, even if it just links to the redmine entry page of that project. -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)

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Moving from trac to a single redmine
by Holger Freyther 25 Sep '16

25 Sep '16

Hi guys, I think some of us would like to move to redmine and start using public tickets more frequently. So in case we move there are some topics to be discussed and I would like to start with a couple of them right now. Tickets: Redmine has a global linear sequence of ticket numbers. If we move from many tracs to a single redmine we can either: * not import tickets * only import from one project * deal with changing ticket numbers In terms of installations the GMR trac is broken in regard to tickets, there are some for SDR that are probably not being fixed anytime soon, baseband might be relevant and OpenBSC is unlikely to be relevant. I don't think we have ever used ticket reference in OpenBSC commit messages so in terms of OpenBSC having changing ticket numbers would not be a big deal. E.g. we could add a custom field with the old trac number? Wiki: We have external references that should be redirected to the new place. Is there any way besides maintaining a list in the apache2/nginx configuration and making redirects as we find broken references? Can we proactively manage this? Is anybody willing to come up with a script and nginx configuration for doing this? kind regards holger

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Help needed with DSP filter problems
by Neoklis Kyriazis 02 Sep '16

02 Sep '16

Hi I have been experimenting writing DSP software, using librtlsdr and a NESDR dongle from NooElec. After much searching the Internet for code to design and implement DSP filters (with little success), I remembered that years ago I bought the "Digital Signal Processing" book by Steven W. Smith. I used the BASIC software included to produce C code to calculate the a and b coefficients for Low Pass or High Pass Chebyshev filters, from 2-pole to 20-pole if needed. Unfortunately, the cut-off frequency for a 6-pole Low Pass filter I implemented turns out to be 2x the required value, even though the design function that calculates the a and b coefficients produces values that match exactly values tabled in the book. This leaves me I think with the following possibilities: 1. That the calculated a and b coefficients are correct but my own code implementing a recursive filter is incorrect. 2. That I have incorporated the LPF filter function into my librtlsdr-based application incorrectly, perhaps misunderstanding parameters like the sampling rate or the required bandwidth. 3. That both the above implementations are correct but the BASIC code included in the book has a bug somewhere, so that both my own results for a and b and those tabled in the book are incorrect. Rather unlikely I thought.... So I am asking for help here from more knowledgeable DSP'ers hoping to resolve this matter, as the above mentioned book is very good, with very clear and simplified teaching of DSP for engineers _and_ it includes source code in BASIC for most of the algorithms it teaches. And it is available openly on the Internet with source code here!: http://dspguide.com/ My own GPL'ed application is available for inspection here: www.5b4az.org/pkg/sdrx/sdrx-0.3-beta.tar.bz2 The filter functions are in src/filters.c and SDR functions in src/rtlsdr.c My thanks here in advance! -- Best Regards Neoklis - Ham Radio Call:5B4AZ http://www.5b4az.org/

1 0

Raspberry Pi 2B
by Leif Asbrink 02 Sep '16

02 Sep '16

Hi All, This video shows that one can run a rtlsdr at 2.4 MHz on a Raspberry Pi 2B. Maybe interesting for portable use. https://www.youtube.com/watch?v=qGZmD8O4Flk Regards Leif

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