October 2015 - 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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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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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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[PATCH] clear warnings about compare signed-unsigned values
by P 10 Jan '16

10 Jan '16

This just removes few annoying warnings. About the conversion of string to signed int. - dev_index = boost::lexical_cast< unsigned int >( hackrf_serial ); + dev_index = boost::lexical_cast< int >( hackrf_serial ); hackrf_device_list_open checks if value of dev_index is out of range (eg negative) and returns proper error. In future negative value can be used for something so this check is not necessary nor wanted. P

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gr-osmosdr setting value in destructor
by P 10 Jan '16

10 Jan '16

Hi, there is in gr-osmosdr a lot of code like: hackrf_source_c::~hackrf_source_c () { ... free(_buf); _buf = NULL; } } Setting value in destructor have sense in two case: - they are used in some way in destructor of parent class - You set then to something like 0xDEADBEEF and when pointer from already destroyed class is used it will cause segfault. Setting value to NULL is contraproductive because there is a lot of checks if value is not NULL, this actually can hide some troubles of calling something using already freed pointer. I'm suggesting to remove this kind of code. I will prepare patch but now I'm waiting if those two pending patches I have send before would be accepter or not. Is there any opinion which oppose previous claim? With best regards, JP.

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[PATCH] librtlsdr: conditional USB transfer resubmit
by P 04 Oct '15

04 Oct '15

This patch implements zero-copy overhead for buffers used for sample transfer. This improves a bit performance for applications where low overhead is required and can save a bit of memory. Two changes are made: * add return value for callback function * add function for buffer release when it is free for reuse This change breaks ABI (callback returns int instead of void), but I cannot find way not to do so. Proper change of library version in CMaleList.txt would be required. Please comment on it and let my now if it is interesting enough to be merged upstream. JP

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[PATCH] do not check for NULL before calling free
by P 04 Oct '15

04 Oct '15

Checking if variable is not NULL before calling free() is not effective, because free() already does this. - waste instruction and/or compiler time - more lines of code than necessary This patch removes those checks.

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SoapyRemote: Turn any SDR into a network peripheral
by Josh Blum 01 Oct '15

01 Oct '15

Hey list, I recently put together SoapyRemote, which is a plugin and server app for SoapySDR that lets any supported hardware operate as a network device over a local link: https://github.com/pothosware/SoapyRemote/wiki GrOsmoSDR users should be able to use the Osmo source and sink blocks to work transparently with a remote device. Just make sure that GrOsmoSDR was configured with the support for SoapySDR. I have documented how the device args should be set to use a remote device: https://github.com/pothosware/SoapyRemote/wiki#grosmosdr-remote-devices Extra note: Everything works better with large socket buffers. On linux, users will want to run the sysctl commands here: https://github.com/pothosware/SoapyRemote/wiki#remote-window I had a lot of fun making SoapyRemote, and we have already seen that working with embedded devices has been a big use case. I hope that GrOsmoSDR users will find utility with SoapyRemote as well. Thanks, and happy hacking! -josh

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[PATCH] gr-osmosdr blocks for the Red Pitaya SDR transceiver
by Pavel Demin 01 Oct '15

01 Oct '15

Hello Dimitri, I've put together two simple gr-osmosdr blocks for the Red Pitaya SDR transceiver. They are based on the file block with some pieces borrowed from the rtl_tcp block. Would it be possible to add these blocks to the gr-osmosdr code repository? The patch is in the attachment. Some information about the Red Pitaya SDR transceiver can be found at: http://pavel-demin.github.io/red-pitaya-notes/sdr-transceiver Best regards, Pavel

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