November 2015 - osmocom-sdr - lists.osmocom.org

Sampling at 250 kHz without aliasing
by Syed Karim 13 May '16

13 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] save gain only when set_gain is successful
by Joseph Poirier 29 Nov '15

29 Nov '15

Signed-off-by: Joseph Poirier <jdpoirier(a)gmail.com> --- src/librtlsdr.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/src/librtlsdr.c b/src/librtlsdr.c index cdf1ca9..fd435b7 100644 --- a/src/librtlsdr.c +++ b/src/librtlsdr.c @@ -1038,13 +1038,10 @@ int rtlsdr_set_tuner_gain(rtlsdr_dev_t *dev, int gain) rtlsdr_set_i2c_repeater(dev, 1); r = dev->tuner->set_gain((void *)dev, gain); rtlsdr_set_i2c_repeater(dev, 0); + if (!r) + dev->gain = gain; } - if (!r) - dev->gain = gain; - else - dev->gain = 0; - return r; } -- 2.5.0

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Hackrf signed issue on gr-osmosdr for ARM
by Del Spangler 25 Nov '15

25 Nov '15

It looks like I'm not the first person to have notices this, because after I submitted a PR to the github project, I noticed another pull request dating from May that has yet to make it into master. Essentially what it boils down to is that char on arm systems, in my case the raspberry pi, are treated as unsigned characters. So right now we have a fix for the hackrf firmware update that only works on x86 systems. A simple change to the source and sink typecasting from char to explicit int8_t on the lookup table on the source.cc should fix this issue for all platforms. In addition, I believe a typecast in the convert function for the sink.cc would do it as well but I have not tested it and I don't believe my current PR reflects that either.

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[PATCH] rtl_fm null squelch
by Wilson Waters 13 Nov '15

13 Nov '15

Hi all, I've created a simple little change for rtl_fm which outputs values of 0 (instead of nothing) when the output is squelched. Use the command option "-E nullsquelch" to enable. This is useful when live streaming output to icecast or similar which requires a constant stream of data (such as http://rtl-sdr.com/forum/viewtopic.php?f=7&t=141 or http://www.windytan.com/2013/07/squelch-it-out.html) Hopefully someone can merge this into the git repo, otherwise just patch and build yourself. Cheers, Wilson -- *Wilson Waters* | Software Engineer *Alintech* e: wilson.waters(a)alintech.com.au w: www.alintech.com.au

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Changing Configuration Parameters Dynamically - OpenBSC
by Amber and Sarosh 04 Nov '15

04 Nov '15

Hi,Can someone inform us if the VTY configuration commands to change parameters e.g. cell id, location area code, MS power etc. that are run on OpenBSC VTY telnet interface take effect on next restart of the OpenBSC session or during the same session? If former is the case, is there any way to dynamically change Cell ID, LAC, MS TX power etc i.e. without restarting the OpenBSC session? Regards, Amber & Sarosh

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