osmocom-sdr

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904 discussions

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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a new and more mature SDR Dongle
by Jay Salsburg 26 Jun '13

26 Jun '13

Have any of you seen this? It appears as though we have a new and more mature SDR Dongle available. http://www.mirics.com/sites/default/files/MSi3101_new.pdf <http://www.mirics.com/node/6> http://www.mirics.com/node/6 Thanks goes out to Francesco for supplying the links to this site

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realtek rumor
by Mathias Coinchon 26 Jun '13

26 Jun '13

Hello, I heard a rumor from someone from industry that Realtek RTL2832u chip would soon be phased out and replaced by another chip (with lower sensitivity according to my contact). Does anybody has more information about this ? Regards Mathias

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Enhancement Request
by jdowjunkmail＠earthlink.net 24 Jun '13

24 Jun '13

Background: Suppose you have four dongles. (That's easy for me. I do.) Suppose they all identify as one of two types. (Three of one and one of the other.) Suppose you want to load a specific dongle when you start the program. And you don't want it to matter if you move the dongles around. How do I do that? Welllll, I hacked. Unfortunately rtlsdr.dll does not allow me to do this even if I alter the serial numbers, at least not the way I want. There is a fly in the rtlsdr ointment when fishing for the USB strings for Manufacturer ID, product ID, and serial number. You must formally open the device to read these values. The dongle can only be opened by one opener at a time. Unfortunately SDRSharp is laid out inside such that it searches for dongles whenever you open Config. And any time you open Config you also have a dongle open. So far this is not too bad a problem. If there's a dongle I cannot poll for strings, that's the one I have open. Er, not so fast, Joanne. What if you have two or more copies open? There will be more than one dongle you cannot poll. I had to figure out how I could identify the dongle I have open even if I move dongles. So I dug in and found some things libusb.dll can do. The chief one is get the USB path for the dongle. And it can do that without actually opening the dongle. Now when filling out the dialog if I cannot read strings for a dongle I get the dongle's path from the device list used and by cheating on the device handle rtlsdr.dll hands out for opened dongles I extracted information I needed to get the path that way. If they compare it's obviously my dongle. If they do not compare it's another dongle that is already opened so I don't show it in the list. Request: Please implement two new entry points which expose the libusb_get_port_path functionality, one by index (same as for strings) and one for rtlsdr handle which I finessed to prove the technique above. The libusb_get_device function will take the device handle and spit out the device list entry that matches the handle. Thanks for considering this. {^_^} Joanne/W6MKU

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rtl_fm question
by Favati 16 Jun '13

16 Jun '13

Hi! I'm modifying rtl_fm to change frequency and demod based on the date/time. For the frequency i've no problem, but changing the modulation from wfm to any other gives me no outout at all. Which is the best approach to change the demod type in realtime? (whitout shutting down rtl_fm of course!) Many thanks!

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e4000 r820t signal output
by Zilvinas, LY2SS 14 Jun '13

14 Jun '13

Hi all ! Please excuse me if this is a bit off topic. Is there any sense to tap the IQ signals from e4k or r820t to the internal or external soundcards. Is it possible at all (with r820t particularly) ? (It could seem like reinventing funcube dongle, bet the performance/price would be still right) Best regards, Zilvinas

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MiricsFlexiTVMSi3101-LinuxSupport
by mrzfrn 13 Jun '13

13 Jun '13

I got a quite good (AM/SW)/FM/DAB/DVB-T USB dongle : Mirics FlexiTV MSi3101. http://www.mirics.com http://www.mirics.com/node/31 WFM , DAB/DAB+ DVB-T signals on air well decoded by Mirics software ( FMDABplayer even on slow netBook, while DVB-T needs fast PC) but Windows binary . I noticed basic Linux software at address http://cgit.osmocom.org/libmirisdr/ What the status of this software just now ( june 2013 )? Thanks. Francesco

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e4000 r820t signal output
by Jay Salsburg 13 Jun '13

13 Jun '13

Yes! Tap. The only problem is a sound card can only accommodate 48K - 96K bandwidth, some maybe as wide as 192K. The noise at the center of tuning may wipe out much of this tuning. What is needed is a tunable "Zero IF" double-balanced converter like a SA602(612) or NC1496 on the output of the Tuner chip driven by a very clean VC oscillator, these chips have differential I/Q inputs so the tuner can be used as it was designed and not constrained by that funky 8-bit A to D chip. A 16 bit I/Q sound card conversion of the double-balanced IF tuner output would reveal much the slow 8 bit converter does not, like very good noise cancelation, ultra narrow-band RADAR signals, very high speed frequency hopping, and spread spectrum modulation. I would create such a thing if I were not involved in more profitable ventures. Jay Salsburg -----Original Message----- From: osmocom-sdr-bounces(a)lists.osmocom.org [mailto:osmocom-sdr-bounces@lists.osmocom.org] On Behalf Of Zilvinas, LY2SS Sent: Wednesday, June 12, 2013 3:14 AM To: osmocom-sdr(a)lists.osmocom.org Subject: e4000 r820t signal output Hi all ! Please excuse me if this is a bit off topic. Is there any sense to tap the IQ signals from e4k or r820t to the internal or external soundcards. Is it possible at all (with r820t particularly) ? (It could seem like reinventing funcube dongle, bet the performance/price would be still right) Best regards, Zilvinas ----- No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.2904 / Virus Database: 3199/6404 - Release Date: 06/12/13

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