osmocom-sdr

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910 discussions

rtl-fm yet another audio cature problem
by Olof Tangrot 18 Nov '12

18 Nov '12

Hi. I have tried (in a bash shell): rtl_fm -f 96.3e6 -s 48000 - | aplay -r raw -f dat -c 1 That was proposed somewhere as an example to listen to an FM station. But everything terminates with: aplay: main:576: bad speed value 0 Found 1 device(s): 0: Realtek, RTL2838UHIDIR, SN: 00000013 Using device 0: ezcap USB 2.0 DVB-T/DAB/FM dongle Found Rafael Micro R820T tuner Oversampling input by: 21x. Oversampling output by: 1x. Buffer size: 8.13ms Tuned to 96552000 Hz. Sampling at 1008000 Hz. Output at 48000 Hz. Exact sample rate is: 1008000.009613 Hz Tuner gain set to automatic. Signal caught, exiting! User cancel, exiting... I run Fedora 16 on a 64-bit AMD machine. aplay version is 1.0.26 If I break the command apart and generates a intermediate file it works but using a pipe does not. So is there some other shell that I where this might work or is there some better why to do this? Regards Olof

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Re: rtl_fm problem with capture audio
by keenerd 15 Nov '12

15 Nov '12

> Vitaliy Kulchevych coolchevy at gmail.com > Wed Nov 14 19:01:02 CET 2012 > > I want grab audio from my sdr-device and convert it to h264. > > I use rtl_fm, check any options, but I can't listen any good sound :( > > For example: rtl_fm -f 10000000 -s 44100 - | mplayer - -quiet > -rawaudio rate=8000:bitrate=44100 -demuxer rawaudio My apologies for breaking threading on this message - just signed up to the ML today. I can't help you without a lot more information. Is this a narrow band or a wide band FM signal? Do you want to save the audio to a file or a network stream? What operating system are you using? Why are you trying to compress an audio stream with a video codec? -Kyle http://kmkeen.com

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Compilation issue
by Leonardo Lazzaro 14 Nov '12

14 Nov '12

Hi! I was trying to compile the osmocom sdr project and also trying to report a compilation error. I will like to have an account to contribute. this was the error I got: In file included from /home/llazzaro/tmp/gr-osmosdr/lib/osmosdr_source_c_impl.h:23:0, from /home/llazzaro/tmp/gr-osmosdr/lib/osmosdr_source_c_impl.cc:30: /home/llazzaro/tmp/gr-osmosdr/include/osmosdr/osmosdr_source_c.h: In constructor ‘osmosdr_source_c::osmosdr_source_c()’: /home/llazzaro/tmp/gr-osmosdr/include/osmosdr/osmosdr_source_c.h:57:19: error: no matching function for call to ‘gr_hier_block2::gr_hier_block2()’ /home/llazzaro/tmp/gr-osmosdr/include/osmosdr/osmosdr_source_c.h:57:19: note: candidates are: /usr/include/gnuradio/gr_hier_block2.h:57:3: note: gr_hier_block2::gr_hier_block2(const string&, gr_io_signature_sptr, gr_io_signature_sptr) /usr/include/gnuradio/gr_hier_block2.h:57:3: note: candidate expects 3 arguments, 0 provided /usr/include/gnuradio/gr_hier_block2.h:43:7: note: gr_hier_block2::gr_hier_block2(const gr_hier_block2&) /usr/include/gnuradio/gr_hier_block2.h:43:7: note: candidate expects 1 argument, 0 provided /home/llazzaro/tmp/gr-osmosdr/lib/osmosdr_source_c_impl.cc: In constructor ‘osmosdr_source_c_impl::osmosdr_source_c_impl(const string&)’: /home/llazzaro/tmp/gr-osmosdr/lib/osmosdr_source_c_impl.cc:83:35: note: synthesized method ‘osmosdr_source_c::osmosdr_source_c()’ first required here make[2]: *** [lib/CMakeFiles/gnuradio-osmosdr.dir/osmosdr_source_c_impl.cc.o] Error 1 make[1]: *** [lib/CMakeFiles/gnuradio-osmosdr.dir/all] Error 2 make: *** [all] Error 2 -- http://www.lazzaroleonardo.com.ar/ twitter @llazzaro

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E4000 undocumented registers?
by Adam Nielsen 11 Nov '12

11 Nov '12

Hi all, I've been looking at the E4000 tuner code and I have a couple of questions that aren't answered in the datasheet. I'm hoping someone here might have some insight. In the Elonics-supplied code[1] when setting the frequency (around line 1339), they always write a 1 into register 0x07 (Synth1), which is the "PLL locked" register. Does this affect anything? The datasheet says it's read only and librtlsdr only ever reads this value, it never writes to it. Then, beginning at 82.9MHz and continuing at every multiple of 28.8MHz above this, the first 7MHz is tuned differently, but the rest of the 21.8MHz in that "channel" is set normally. This stops between 233.9MHz and 485.6MHz, then resumes again at 8MHz increments instead of 7MHz up until 868MHz. When tuned differently, register 0x05 (Input clock) gets set to 3, which isn't listed in the datasheet (and also says 'do not write to this register'). Mostly (but not always) when this happens (i.e. first 7-8MHz of the channel), register 0x07 bits 3-4 are also set to various arbitrary values. The datasheet says 0 means "16-32MHz input clock freq range" but this code writes 1 and 2 into this field as well. It seems to write approximately these values: 1 up to 89.9MHz 0 up to 118.7MHz 1 up to 205.1MHz 2 up to 233.9MHz 0 up to 551.2MHz 1 up to 752.8MHz 2 up to 868MHz 0 after 868MHz After the first 7-8MHz the rest of the 28.8MHz channel has the default 0 value set. Does anyone know what these values control? As a side note, register 0x08 (Synth2) appears to do something even though it's listed as reserved. By setting particular bits I can get the rtl_test program to not lock on to any frequency, but oddly enough rtl_fm still works fine. I'm not sure what to make of this yet. I don't suppose this register is documented anywhere else? I'm just wondering whether the datasheets supplied by Elonics are different to the one that is now public. Thanks, Adam. [1]: One of many copies is at https://github.com/mbarbon/rtl2832/blob/master/tuners/tuner_e4000.c

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removing the L-band gap on E4000
by Jacek Lipkowski 09 Nov '12

09 Nov '12

Hello I've tried to remove the L-band gap on my E4000 tuner by changing the divisors. Please see the patch below. I don't have a signal source to test today, so i'm not sure if it works, but the pll locks. I will try to test tomorrow. Without my hack: E4K L-band gap: 1093 to 1233 MHz With my hack: sq5bpf@dellix:~/gnuradio/rtl-sdr/src$ ./rtl_test -t Found 1 device(s): 0: ezcap USB 2.0 DVB-T/DAB/FM dongle Using device 0: ezcap USB 2.0 DVB-T/DAB/FM dongle Found Elonics E4000 tuner Supported gain values (14): -1.0 1.5 4.0 6.5 9.0 11.5 14.0 16.5 19.0 21.5 24.0 29.0 34.0 42.0 Benchmarking E4000 PLL... [E4K] PLL not locked for 51000000 Hz! [E4K] PLL not locked for 2186000000 Hz! E4K range: 52 to 2185 MHz E4K L-band gap: 0 to 0 MHz Regards Jacek / SQ5BPF --- tuner_e4k.c.orig 2012-11-08 22:08:07.000000000 +0100 +++ tuner_e4k.c 2012-11-08 23:01:05.000000000 +0100 @@ -35,6 +35,7 @@ /* If this is defined, the limits are somewhat relaxed compared to what the * vendor claims is possible */ #define OUT_OF_SPEC +#define HACKED_DIVISORS #define MHZ(x) ((x)*1000*1000) #define KHZ(x) ((x)*1000) @@ -357,7 +358,14 @@ {KHZ(350000), (1 << 3) | 1, 8}, {KHZ(432000), (0 << 3) | 3, 8}, {KHZ(667000), (0 << 3) | 2, 6}, - {KHZ(1200000), (0 << 3) | 1, 4} +#ifdef HACKED_DIVISORS +/* the original settings seem to be ripped from some Elonics driver, + * however changing them a bit removes the L-band gap + * change this to a bit more then the end of your L-band gap --sq5bpf */ + {KHZ(1270000), (0 << 3) | 1, 3} +#else + {KHZ(1200000), (0 << 3) | 1, 4} +#endif }; static int is_fvco_valid(uint32_t fvco_z)

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RTL-SDR with MSI DIGIVOX Micro HD support
by Höss Lajos 08 Nov '12

08 Nov '12

Hi, Good news with MSI DIGIVOX Micro HD (1d19:1104) DVB-T tuner. Now the tuner working. Succesfully received analague UHF TV sound channel 80 kilometer distance from transmitter, taxi driver (164 Mhz) and one frequency from 70cm radio amateur band. The tuner is FCI FC2580 from debug message. I see on http://sdr.osmocom.org/trac/wiki/rtl-sdr great new info for this tuner 146 - 308 MHz and 438 - 924 MHz (gap in between). Not have any wideband generator for check this, but for example with strong local FM radio station 87.5-108MHz tunable, but received only noise. I think the frequency range possibly same. All rtl-sdr DVB-T tuner with fc2850 has a same frequency range? I interesting for not working frequiency, working frequiency or working freq. but poor receiver quality, or any gap. I interesting also for 2 meter radio amateur band, only max. 2 MHz lower. 144-146MHZ only noise received, i not know my antenna bad, or this is not possible. mngc

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Small thinko in testing for clock_gettime
by Pete Zaitcev 08 Nov '12

08 Nov '12

This appears to be not tested with autoconf (cmake works). The assignment to $LIBS changes nothing, which cannot possibly be the intent. --- cc-ing to original patch author and sign-off diff --git a/configure.ac b/configure.ac index 1b94701..c760787 100644 --- a/configure.ac +++ b/configure.ac @@ -40,7 +40,7 @@ dnl libmath (for rtl_fm) AC_CHECK_LIB(m, atan2, [LIBS="$LIBS -lm"]) dnl librealtime (for rtl_test) -AC_CHECK_LIB(rt, clock_gettime, [LIBS="$LIBS"]) +AC_CHECK_LIB(rt, clock_gettime, [LIBS="$LIBS -lrt"]) # The following test is taken from WebKit's webkit.m4 saved_CFLAGS="$CFLAGS"

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Latest Ubuntu update
by James Peroulas 04 Nov '12

04 Nov '12

I'm running Ubuntu 12.04 and after installing all the latest security and recommended updates, I'm having problems with the rtlsdr library relating to rtlsdr_cancel_async. For example: rtl_sdr -f 739000000 -n 1000000 cap.dat The above will successfully capture exactly 1M samples into cap.dat, but it will not exit after the capture is finished. I have to break out with ctrl-c. Anybody having similar problems? Hoping I don't have to re-install Ubuntu... :( James -- *Integrity is a binary state - **either you have it or you don’t.* - John Doerr

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4Mbps hack wiring & 48 MHz spurs
by Sylvain Munaut 02 Nov '12

02 Nov '12

Just fyi, here's how I did the 4msps wiring hack : http://i.imgur.com/TODkU.png Basically use resistors (I used 270R which is a bit high ,between 20 and 10R would bwe better) on the back side on the PCB. I initially started with wire jumpers on the pins, then moved to resisors on the top but that created a huge loop area with the ground return (there is no gnd on those connection) which was heavily radiating. Mounting on the back like that dropped it significantely for me (especially on baseband), but you still clearly see it. I think the FPGA drive strength on the data pins is still way too high and should be reduced. Maybe using spread spectrum on the MCI would be another idea ? Cheers, Sylvain

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Beginner question about rtlsdr
by Jared Clements 28 Oct '12

28 Oct '12

Hi list, hi Michel, I'm new here, but have been working on the same solution as you are, but for an Amsat all sky tracking receiver. First, let me point you to the signal processing textbook I've been working my way through: dspguide.com. It can be a bit verbose for a textbook, but that's been to my advantage several times. I've run into two clear obstacles trying to build an interferometric array. Both have to do with clock synchronization. First is clock drift. No matter how expensive the crystal, or precise the temperature control, two clocks are going to drift with respect to each other. I'm planning on solving this one by pulling the crystal off the dongles and replacing it with a clock input that I'll pipe from one single clock/crystal out to each dongle. I'm assuming that I'll have to use equal length cables to keep my timing correct. The second problem is synchronizing the separate data streams so I know which samples were taken at the exact same time. This one is a bit trickier, and I don't think there's a hardware solution for it. Most multichannel data acquisition systems have a trigger system to solve this, where all the channels get initialized but don't start to capture until the trigger is received. Unfortunately I don't think there's a trigger input pin anywhere in our dongles. There is another way, and that's find a known RF signal that we can use for synchronization. GPS would be ideal, because there's explicit solutions for time offsets/drift that's referenced to atomic clocks. We could record 5 minutes or so on the L1 band before an observation, then mid-capture tune to our frequency of interest...assuming we can shift the e4k chip without interupting the RTL2832 in it's capture sequence. Does anyone here know if this is possible? Shift the tuner without interupting the capture? This does require a wide band antenna, best options seem to be spiral and conical spiral. There's probably other options, like an active gps patch antenna that's duplexed in with a frequency specific duplexer, but I'm not much of an rf guy and I like the simplicity of the single wide band antenna. I've also been looking at options for building out an array, I've seen reports that a good LNA can get 20dB in SNR, but a wideband preamp runs $70 on minicircuits website. Plus the cost of a bias T and a clean power supply. And I'm not sure that I understand all the built-in options for amplification and filtering yet. That design trade is still pretty fuzzy. It might be more cost effective to just buy more dongles and get better SNR through summing their outputs. More research required!

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