- osmocom-sdr - lists.osmocom.org

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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Re: ACARS decoder using rtl-sdr
by Pawel Janowski 19 Jul '13

19 Jul '13

Hello its great idea ! I think the next step (small for man big form mankind) should be decoding (based on rtl_fm) APRS messages and putting into APRS-IS Servers ! with regards Pawel, SQ7MRU http://sq7mru.blogspot.com/

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Re: ACARS decoder using rtl-sdr
by Adam Nielsen 19 Jul '13

19 Jul '13

> Hi, > > The grab connection doesn't work :( > > 73, Murat TA1DB If you're running a recent version of Linux, it will load DVB drivers so you can watch TV with the device. You'll have to unload these to make the device available for use: sudo rmmod dvb_usb_rtl28xxu rtl2832 e4000 (assuming an e4000 device, not sure what module to unload for other tuners, lsmod will tell you.) Cheers, Adam.

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Possible bug in device removal detection code in librtlsdr.c
by Alexey Kruglov 16 Jul '13

16 Jul '13

Hi. Device removal detection code in _libusb_callback in librtlsdr.c may be buggy. Every time we get any status other than LIBUSB_TRANSFER_COMPLETED (including LIBUSB_TRANSFER_ERROR) the code doesn't resubmit current buffer, and we get the real number of working buffers decreased by one. If that number goes down to 0, rtlsdr_read_async() will hang. Linux version tries to control it by counting the number of LIBUSB_TRANSFER_ERROR buffers that came in row in dev->xfer_errors. But if we already have _one_ failed buffer during the whole transfer up to the moment, that counter will never reach dev->xfer_buf_num. So it seems more straightforward to 1. count the failed buffers and rtlsdr_cancel_async() when it reaches 0 or some sensible threshold, and 2. maybe resubmit some kinds of the failed buffers other than LIBUSB_TRANSFER_COMPLETED, if it makes sense. I am not a libusb guru and it's not well documented in this part, so I am not sure about my second point. Hoping some librtlsdr developers will appear on this list. -- GPG fp: 6DFA 1186 7576 DE60 6CCB EB39 AD81 1733 EEBB 970A

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Delay after rtlsdr_cancel_async
by Alexey Kruglov 16 Jul '13

16 Jul '13

Hi. I noticed there is a 1 second delay in librtlsdr between calling rtlsdr_cancel_async and releasing from rtlsdr_read_async. I'm writing a radio scanner and this delay limits scanning speed considerably. I tracked the delay down to this piece of code in librtlsdr.c: while (RTLSDR_INACTIVE != dev->async_status) { r = libusb_handle_events_timeout(dev->ctx, &tv); [...] if (RTLSDR_CANCELING == dev->async_status) { next_status = RTLSDR_INACTIVE; [...] if (dev->dev_lost || RTLSDR_INACTIVE == next_status) { >>>> libusb_handle_events_timeout(dev->ctx, &tv); break; } The marked line is almost always(?) invoked when all the events are already processed, hence it blocks for tv = 1 second. In fact I don't understand what this `if' is supposed to do at all. I tried to modify this line by changing the delay to 0 making it a non-blocking call (leaving the timeout of 1 sec for the former libusb_handle_events_timeout call). This worked with my project and the 1 second delay disappeared. So, I suppose, it's better to either a) remove the whole `if' or b) make the latter libusb_handle_events_timeout non-blocking as I did. I checked that b) works for me, and didn't test a) yet. The question is: what that `if (dev->dev_lost ...' is supposed to do? And the two possible fixes for 1 second delay bug depending on the answer are (diffs): === 1630a1631 > struct timeval tv_nb = { 0, 0 }; 1696c1697 < libusb_handle_events_timeout(dev->ctx, &tv); --- > libusb_handle_events_timeout(dev->ctx, &tv_nb); === === 1694,1698d1693 < < if (dev->dev_lost || RTLSDR_INACTIVE == next_status) { < libusb_handle_events_timeout(dev->ctx, &tv); < break; < } === -- GPG fp: 6DFA 1186 7576 DE60 6CCB EB39 AD81 1733 EEBB 970A

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Anybody running gr-osmosdr or gr-baz under Windows?
by Murat Toloğlu 09 Jul '13

09 Jul '13

Hi All, After more than 2 weeks of endless trials to build, install and run gr-osmosdr and/or gr-baz in Windows 7 to have an RTL2832 source in GNU Radio - GRC without success I really wander if anybody exists and running these programs under Windows? Do you know anybody who succeeded to build and install gr-osmosdr and/or gr-baz in Windows? Regards, Mu

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minimum sample rates?
by David Jacobowitz 27 Jun '13

27 Jun '13

I'm trying to write some code that uses a Raspberry Pi not just to capture the samples, but also to do the DSP. The signal I'm working (aviation VOR) is narrow and the DSP is not too hard-core, but it'll be easier if I can sample at a lower rate. Though rtlsdr_set_sample_rate returns no errors and rtlsdr_get_sample_rate returns the same value I gave it (or quite close), it does not appear to be working. I had been working at 250ksps but wanted to try 125ksps or even 62500sps, but none of those seem to work. Is this just a limitation of the hardware? I have a NooElec RTL2832 / R820T device if that matters. Regards, Dave J

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