osmocom-sdr July 2013

osmocom-sdr@lists.osmocom.org

12 participants
15 discussions

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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osmocom-sdr July 2013