osmocom-sdr October 2016

osmocom-sdr@lists.osmocom.org

8 participants
5 discussions

RTL-SDR and RTL-TCP drivers
by Krzysztof Halasa 12 Jun '17

12 Jun '17

Hello, it's my first mail on this list, so please forgive me if I do something wrong. I'm about to post a couple of patches for RTL drivers: 1. RTL-SDR: convert _lut to float[] to reduce size by a factor of 256. The _lut is being indexed by I + Q (16 bits = 65536 entries), however both samples can be processed independently, resulting in 8-bit LUT. Saves a bit of RAM and CPU cache. lib/rtl/rtl_source_c.cc | 19 ++++++------------- lib/rtl/rtl_source_c.h | 4 ++-- 2 files changed, 8 insertions(+), 15 deletions(-) 2. RTL-TCP: Convert to single class model The existing RTL TCP driver is quite different from its brother RTL_SDR. It's much more complicated, uses gr::blocks::deinterleave and gr::blocks::float_to_complex, and generally doesn't work correctly (e.g. https://github.com/csete/gqrx/issues/99 Spectrum is mirrored when filter or demodulator changes (rtl_tcp) #99) I've converted the RTL TCP driver to the model used by RTL_SDR, simplifying it in the process, and fixing the GQRX issue. lib/rtl_tcp/CMakeLists.txt | 1 - lib/rtl_tcp/rtl_tcp_source_c.cc | 352 ++++++++++++++++++++++++++++++++-------- lib/rtl_tcp/rtl_tcp_source_c.h | 32 +++- lib/rtl_tcp/rtl_tcp_source_f.cc | 327 ------------------------------------- lib/rtl_tcp/rtl_tcp_source_f.h | 125 -------------- 5 files changed, 309 insertions(+), 528 deletions(-) I'm also thinking about merging the code common to RTL-SDR and RTL-TCP, but this it's done yet. Comments? -- Krzysztof Halasa

2 3

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.

4 3

[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

2 1

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

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osmocom-sdr October 2016