January 2016 - osmocom-sdr - lists.osmocom.org

Sampling at 250 kHz without aliasing
by Syed Karim 12 May '16

12 May '16

We have a need for a small sample rate on the rtl-sdr. We have been able to select a bandwidth of 250 kHz, but there is significant aliasing at that setting. At higher sample rates the aliasing no longer exists. We are using the dongle that is sold by the RTL-SDR.com blog: http://www.rtl-sdr.com/new-products-rtl-sdr-with-1ppm-tcxo-sma-f-connector-… Since a reduced sample rate would allow for a much less resource consumption by the CPU, we would gladly sponsor an open source bounty or pay for open source development work to address this problem. Our use case is reception of a 5 kHz channel from a geostationary L-band operator. We have found that the dongle gets very hot at 1550 MHz, so we will use an LNB to downconvert to ~400 MHz. The rest of the RF chain consists of a patch antenna with 8 dBi of gain and 17 dBW EIRP from the spacecraft. The demodulator will be running on a derivative of the Beagle Bone Black. The designs for this board are available here: https://github.com/outernet-project/lantern-compute-pcb You can learn more about Outernet through the following links. http://gizmodo.com/what-is-the-outernet-and-is-it-the-future-of-the-intern-… http://www.wired.com/2015/07/plan-beam-web-3-billion-unconnected-humans/ http://www.technologyreview.com/news/537411/startup-beams-the-webs-most-imp…

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Heatmap with unwanted vertical lines
by John 12 May '16

12 May '16

Hello, When I use heatmap.py with output from rtl_power I get regularly spaced vertical lines that do not appear to be related to any signal. They look they like repeat at the dongle bandwidth (2048000Hz in this case). The crop option for rtl_power reduces the presence but I am not sure f that is intended by that option. Even at -c of 70% they are still there (see attachment). Is this because of small bin width? If I use a larger bin (32k) they are still there. In this case there is no frequency legend along top so can't compare if they happen more often. Are these lines to be expected? John

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Fixing gr-fosphor compilation
by Elliot Saba 11 May '16

11 May '16

After pulling gr-fosphor `master` today and compiling against the latest GNURadio, I noticed that it failed when attempting to link against libgnuradio, due to missing pmt symbols. The attached one-line patch fixes the issue, but I imagine would break compilation against older GNURadio releases. If there is a better way for me to submit this patch, please let me know. I had previously emailed one of the gr-fosphor developers with a separate issue regarding libpng issues out of ignorance of this mailing list. I don't want to disturb you developers any more than need be, so if there is a better forum than this for patches/pull requests, I am more than happy to use it. -E

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sdrangelove build issues on mipsel
by Arturo Borrero Gonzalez 03 May '16

03 May '16

Hi there, In debian, sdrangelove is having some build issues on mipsel [0]. At first, there was an issue regarding the '-msse2' switch. If I delete the switch, then another build error happens: ======== 8< ======== [...] [ 21%] Building CXX object CMakeFiles/sdrbase.dir/sdrbase/dsp/interpolator.cpp.o /usr/bin/c++ -DQT_CORE_LIB -DQT_GUI_LIB -DQT_MULTIMEDIA_LIB -DQT_NETWORK_LIB -DQT_NO_DEBUG -DQT_OPENGL_LIB -DQT_WIDGETS_LIB -DUSE_FFTW -Dsdrangelove_EXPORTS -g -O2 -fstack-protector-strong -Wformat -Werror=format-security -D_FORTIFY_SOURCE=2 -O3 -DNDEBUG -fPIC -isystem /usr/include/mipsel-linux-gnu/qt5 -isystem /usr/include/mipsel-linux-gnu/qt5/QtCore -isystem /usr/lib/mipsel-linux-gnu/qt5/mkspecs/linux-g++ -isystem /usr/include/mipsel-linux-gnu/qt5/QtWidgets -isystem /usr/include/mipsel-linux-gnu/qt5/QtGui -isystem /usr/include/mipsel-linux-gnu/qt5/QtOpenGL -isystem /usr/include/mipsel-linux-gnu/qt5/QtMultimedia -isystem /usr/include/mipsel-linux-gnu/qt5/QtNetwork -I/tmp/buildd/sdrangelove-0.0.1.20140824/obj-mipsel-linux-gnu -I/tmp/buildd/sdrangelove-0.0.1.20140824/include -I/tmp/buildd/sdrangelove-0.0.1.20140824/include-gpl -fPIC -o CMakeFiles/sdrbase.dir/sdrbase/dsp/interpolator.cpp.o -c /tmp/buildd/sdrangelove-0.0.1.20140824/sdrbase/dsp/interpolator.cpp In file included from /tmp/buildd/sdrangelove-0.0.1.20140824/sdrbase/dsp/interpolator.cpp:4:0: /tmp/buildd/sdrangelove-0.0.1.20140824/include-gpl/dsp/interpolator.h:4:23: fatal error: immintrin.h: No such file or directory #include <immintrin.h> ^ compilation terminated. [...] ======== 8< ======== Do you have any hint for this? Thanks, best regards. PS: Please keep me in CC, i'm not subscribed. [0] https://buildd.debian.org/status/fetch.php?pkg=sdrangelove&arch=mipsel&ver=… -- Arturo Borrero González

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Airspy patch to enable USB bit packing
by Martin Smith 28 Feb '16

28 Feb '16

Last July there were several changes made to the Airspy firmware and libairspy that added support for a new bit packing mode where 4 sets of 12 bit samples are packed into 3 sets of 16 bits for the transfer across the USB bus ( https://i.imgur.com/qXnWoEK.png?1 ). 25% less data is transferred across the bus and this is good for some computers with cheap USB chipsets. There is an overhead of extra memory bandwidth required on the host side to unpack the data into a useful format, so for optimal performance bit packing is disabled by default. The data is automatically unpacked within libairspy before being passed along, so no changes are required anywhere else if packing is enabled (or not enabled). Airspy firmware older than v1.0.0-rc6 does not have the function, but that is detected and handled by libairspy. I wrote the attached patch to enable packing in gr-osmosdr, which I tested and it works. It is basically a clone of the bias=0|1 lines as pack=0|1 and calls the needed libairspy function. ref: https://github.com/airspy/firmware/commit/7e1806b https://github.com/airspy/firmware/commit/5b7dcab https://github.com/airspy/host/commit/a51eccb --- Do some Baseline test with Airspy command line tools to have something to compare USB throughput results -------------------------------------------------------------------------------------------------------- $ sudo mount -t debugfs none /sys/kernel/debug $ sudo modprobe usbmon $ wireshark -i usbmod3 & $ airspy_info ; sleep 120 ; \ airspy_rx -t 4 -r /dev/null -n 2400000000 ; sleep 120 ; \ airspy_rx -t 4 -r /dev/null -p 1 -n 2400000000 ; sleep 120 ; \ airspy_info Wireshark->Statistics->IO Graph The Bytes/Tick are double the actual data rate because of way wireshark collects the USB packets, I could have added a filter to fix this. But the relationship is valid 25% less with packing enabled. The data rate in the IO Grahp drops from 80MB/sec (in+out) [really 40MB/sec] to 60MB/second (in+out) [really 30MB/sec] from unpacked to packed. 10MSPS no packing, packing https://i.imgur.com/pA9LPdE.png?1 2.5MSPS no packing, packing https://i.imgur.com/lA8q5aq.png?1 Verification test with my patched gr-osmosdr -------------------------------------------- $ sudo mount -t debugfs none /sys/kernel/debug $ sudo modprobe usbmon $ wireshark -i usbmod3 & $ osmocom_fft -a "airspy=0" -s 10000000 --fft-rate=1 $ osmocom_fft -a "airspy=0,pack=1" -s 10000000 --fft-rate=1 $ osmocom_fft -a "airspy=0" -s 2500000 --fft-rate=1 $ osmocom_fft -a "airspy=0,pack=1" -s 2500000 --fft-rate=1 $ osmocom_fft -a "airspy=0" -s 2500000 --fft-rate=1 $ osmocom_fft -a "airspy=0,pack=0" -s 2500000 --fft-rate=1 I ran all of the above tests and the wireshark USB throughput graphs showed exactly what was expected. 40MB/sec(10MSPS+normal),30MB/sec(10MSPS+packing),10MB/sec(2.5MSPS+normal),7.5MB/sec(2.5MSPS+packing),10MB/sec(2.5MSPS+normal),10MB/sec(2.5MSPS+normal). 25% less when packing was enabled and if you did not specify the "pack=1", then no bit packing is performed by libairspy. All the magnitudes within the FFT windows looked exactly the same as they do without bit packing.

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[patch]: rtl_sdr, fix -n parameter
by Henk 08 Feb '16

08 Feb '16

Fix bytes_to_read adjustment in callback. For example bug exposes itself with: rtl_sdr -f 100e6 -s 2048000 -n 245.76e6 /tmp/100M.iq and does not terminate after the expected 245.76e6 samples. Which is an exact multiple of "out_block_size". Signed-off-by: Henk vergonet <henk.vergonet(a)gmail.com>

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Ubuntu+Windows binaries for GNURadio/GrOsmo
by Josh Blum 31 Jan '16

31 Jan '16

Hey list, This is an update and an announcement: Alexandru Csete and I have been maintaining an Ubuntu PPA for SDR community software for some time. We just updated to GNU Radio 3.7.9 and GrOsmoSDR with RedPitaya support. The goal of the PPA is to have have recent releases of community software (SDR drivers, GNU Radio, and related projects) across several versions of Ubuntu. Simply follow the apt-get instructions here: http://wiki.myriadrf.org/Packaging I figure that a lot of people (both developers and users) can benefit from the shared effort. If you find a bug, have a request, or want to get involved; please let us know, we would love to hear it: https://discourse.myriadrf.org/c/projects/packaging On the windows side of things, I am pleased to announce the PothosSDR installer/development environment; which now includes around 40 open source projects. We just updated to the latest GNURadio/GrOsmoSDR, and recently additions include GQRX, gr-rds, and zeromq support. Instructions for GNURadio/GRC and GQRX users: https://github.com/pothosware/PothosSDR/wiki/GNURadio https://github.com/pothosware/PothosSDR/wiki/GQRX Special thanks to Andrew Back and Myriadrf for all of the support and hosting the software! Thanks, -josh

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Distinction between librtlsdr and rtl-sdr repositories
by Murat Tologlu 24 Jan '16

24 Jan '16

Hi, I appreciate very much to receive your comments on the distinctions between steve-m/libsrtlsdr and keenerd/rtl-sdr (forked from pinkavaj/rtl-sdr 129 commit ago and maintained). Both have very similar structure, flies, purpose but the software is not exactly same. There are something attractive for me in one of them while the other one is also good. İs it possible to create patch from one of them and apply to the other to merge two repos together?? Why I am asking is, rtl-sdr has a new agc - aggressive agc option which is useful for me but I prefer to stay on librtlsdr; is there a solution? Thanks in advance, Murat.

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peekSDR
by Magnus Paulsson 16 Jan '16

16 Jan '16

I’ve been playing with a python application to scan, find and record strong signals. I attached the code with the hope that someone would like to improve it … maybe put it on sourceforge or github. I will not have time to do anything about it for a few weeks. Works at least with linux … haven’t tried OSX or win. Needs: numpy, scipy, matplotlib, npyscreen (https://pypi.python.org/pypi/npyscreen/) pyrtlsdr (https://github.com/roger-/pyrtlsdr/releases [use the old release, new code python 3 only]) start with: python peekSDR.py -d (in one window to start database) python peekSDR.py -vr (in one window to start radio scanning) python peekSDR.py -g (in one window to start user interface) [can be run on different computers as long as you have the same filesystem and stand in the same directory] in the user interface “f” plots ffts of recorded signals. “1” starts gqrx with the recorded signal. Best wishes - Magnus

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Re: [rtl-sdr][PATCH 1/2] rtl_fm: Add scanner progress
by Nikolay Dimitrov 15 Jan '16

15 Jan '16

Oops, forgot to CC the mailing list. On 09/21/2015 12:47 PM, Nikolay Dimitrov wrote: > Hi Dimitri, > > On 07/04/2015 03:42 PM, Nikolay Dimitrov wrote: >> Add scanner progress, including signal and squelch levels. >> Rename demod_state->conseq_squelch to demod_state->squelch_conseq. >> >> The scanner progress feature can be tested like this: >> >> ./rtl_fm -f 144.000M:146.000M:25k -M fm -s 48k -l 100 -t 5 | aplay \ >> -r 48k -f S16_LE -t raw -c 1 >> >> Signed-off-by: Nikolay Dimitrov <picmaster(a)mail.bg> >> --- >> src/rtl_fm.c | 43 +++++++++++++++++++++++++++++-------------- >> 1 file changed, 29 insertions(+), 14 deletions(-) > > Can you please take a look at this patch and decide whether it's worthy > of applying to the rtl-sdr tree? > > Thanks in advance. Regards, > Nikolay

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