osmocom-sdr

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910 discussions

Sniffing digital wireless protocols at 2.4Ghz with RTL-SDR
by Omri Iluz 23 Jan '14

23 Jan '14

I was able to decode NRF24L01+ and Bluetooth Low Energy protocols using RTL-SDR. with some very cheap analog trickery. This opens a world of possibilities at the ISM 2.4Ghz band. Detailed walk-through of the journey from idea to a working solution at http://blog.cyberexplorer.me/2014/01/sniffing-and-decoding-nrf24l01-and.html Code at https://github.com/omriiluz/NRF24-BTLE-Decoder Thought it would be interesting for the folks here. Also, I it would be great if you can add me to the list of decoders at http://sdr.osmocom.org/trac/wiki/rtl-sdr

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Another failure of decoding UAT
by Pete Zaitcev 23 Jan '14

23 Jan '14

Guys, As you know, our sample rate is not good enough to decode UAT's FSK in a conventional way, so I thought to try something else: use 2 samples per bit to detect the frequency shift. This is obviously unreliable, but I hoped to see something at least. But it didn't work: seems like decoding noise. The code is here: https://github.com/zaitcev/ruat Anyone is willing to critique? Where did I go wrong? Thanks, -- Pete

4 5

stack-fault in rtl_fm.exe
by Gisle Vanem 23 Jan '14

23 Jan '14

The rtl_fm program uses approx 1.8 MByte for it's stack. Mostly used for 'stuct fm_state'. The default stack-size for a Windows program is 4kB (it can dynamically grow). I've compiled using MSVC v16 and option '-GS'. Ref: http://support.microsoft.com/kb/100775 Adding '-stack:2000000' to the link stage works fine here. Or alloca() or malloc() could be used? Or 'fm' could be made static? --gv

1 0

what to see
by 393775602 22 Jan '14

22 Jan '14

Hi， i have just transmited the rtl-sdr code into android using NDK，and i start the rtl-sdr and set the fequecny,samp_rate and so on. Finally i get the output from rtl and write it into a txt file. Then the problem came, i open the txt and find it a mess, does the output decode in utf-8 or something else,can anyone give me a look to see what output is like Thanks a lot chenzujie

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Use multi-dongles to speedup identifying all available/detectable GSM downlink broadcasting carrier
by Jiao Xianjun 22 Jan '14

22 Jan '14

Hi, As a "side product" of this thread: "How to get IQ samples from multiple rtl-sdr dongles in a synchronized manner",A scanning tool is released for identifying all available/detectable GSM broadcasting carrier around you quickly. You can find it here: http://www.mathworks.com/matlabcentral/fileexchange/45152-rtl-sdr-multi-don… or https://github.com/JiaoXianjun/multi-rtl-sdr-calibration By using 3 dongles, we can identify all available/detectable GSM broadcasting carrier in the whole PGSM band downlink 935~960MHz in 30s (my intel i7 12-core station) instead of 80s (only one dongles). The original purpose of project multi-rtl-sdr-calibration is that calibrating multiple dongles by the common GSM source. So the first thing need to do is that finding out where is the strongest GSM signal in the air. This script (multi_rtl_sdr_gsm_FCCH_scanner.m) can identify GSM downlink broadcasting carrier by detecting successive multiple FCCH bursts of all possible carrier in a band you specify, such as PGSM downlink 935~960MHz. I learn knowledge of GSM frame structure from here: http://www.sharetechnote.com/html/FrameStructure_GSM.html After the script is run, quality metrics of detected FCCH channel per frequency will be displayed: SNR and number of detected FCCH burst (num of hits). Note: for speedup detection algorithm, a large decimation ratio is used, thus shown SNR may be lower than actual SNR. But it is enough to help us idendify which frequency is best. README is also pasted here: Multiple rtl-sdr(rtl_tcp) dongles based GSM FCCH scanner. ( putaoshu(a)gmail.com; putaoshu(a)msn.com) multi_rtl_sdr_gsm_FCCH_scanner.m Have multiple dongles run concurrently to speedup detecting FCCH(Frequency correction channel) burst in wide GSM band by scanning different sub-band with different dongle. This is a sub script of project: https://github.com/JiaoXianjun/multi-rtl-sdr-calibration ------------Purpose------------ The original purpose of project multi-rtl-sdr-calibration is that calibrating multiple dongles by the common GSM source. So the first thing need to do is that finding out where is the strongest GSM signal in the air. This script can identify GSM downlink broadcasting carrier by detecting successive multiple FCCH burst. I learn knowledge of GSM frame structure from here: http://www.sharetechnote.com/html/FrameStructure_GSM.html After the script is run, quality metrics of detected FCCH channel will be displayed: SNR and number of detected FCCH burst (num of hits). Note: for speedup detection algorithm, a large decimation ratio is used, thus shown SNR may be lower than actual SNR. But it is enough to help us idendify which frequency is best. -------------Usage------------- 1. Assume that you have installed rtl-sdr (http://sdr.osmocom.org/trac/wiki/rtl-sdr) and have those native utilities run correctly already. For example, you have multiple dongles, please run multiple rtl_tcp in multiple shell respectively as: rtl_tcp -p 1234 -d 0 rtl_tcp -p 1235 -d 1 rtl_tcp -p 1236 -d 2 ... 2. Then run multi_rtl_sdr_gsm_FCCH_scanner.m in MATLAB. ATTENTION! In some computer, each time before you run script, maybe you need to terminate multiple rtl_tcp and re-launch them again. ATTENTION! Please reduce number of inspected points by reducing frequency range, if your computer hasn't enough memory installed. Because all sigals are stored firstly before processing. Change following parameters in the script as you need: num_dongle = 1; % number of dongles you installed start_freq = 935e6; end_freq = 960e6; freq_step = 0.2e6; % GSM channel spacing gain = 0; ... Some key parameters: % how long signal we try to find multiple FCCH bursts in num_frame = 64; % roughly speaking, there are 1 FCCH burst per 10 frames, but 50 frames plus 1 idle frame construct one multiframe FCCH_coarse_position.m th = 10; % Peak to average threshold of detecting FCCH in moving averaging SNR(estimated by FFT) stream. max_offset = 5; % +/- range of predicted next postion of FCCH burst. ------------Algorithm------------ Because FCCH actually is a period of CW signal, we can use FFT to see if there is sharp peak in frequency domain. For the first FCCH detection, a continuous moving FFT is performed. After the first FCCH is hit, the following FCCH will be only detected at predicted position (+/- small range) according to GSM frame structure. At least 3 successive FCCH need to be detected for we to ensure one donwlink broadcasting carrier is there. See details in FCCH_coarse_position.m.

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[omri@iluz.net: Sniffing and decoding NRF24L01+ and Bluetooth LE packets using RTL-SDR]
by Harald Welte 22 Jan '14

22 Jan '14

Dear all, with the permission of the original poster, I hereby forward a message from Omri regarding his use of rtl-sdr to sniff and decode NRF24L01+ and Bluetooth LE packets. I have no involvement in the project, I'm just passing on the mail, thats' all ;) Regards, -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)

2 1

sdrangelove: Allow to select build type on command line
by bon＠elektron.ikp.physik.tu-darmstadt.de 21 Jan '14

21 Jan '14

-- Uwe Bonnes bon(a)elektron.ikp.physik.tu-darmstadt.de Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt --------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------

1 0

cmake: Allow to choose build type on command line.
by Uwe Bonnes 21 Jan '14

21 Jan '14

--- CMakeLists.txt | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/CMakeLists.txt b/CMakeLists.txt index ab899f2..9a6a2f1 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -3,9 +3,12 @@ list(APPEND CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake/Modules) project(sdrangelove) -set(CMAKE_BUILD_TYPE "Release") +#set(CMAKE_BUILD_TYPE "Release") #set(CMAKE_BUILD_TYPE "ReleaseWithDebugInfo") #set(CMAKE_BUILD_TYPE "Debug") +if (NOT DEFINED CMAKE_BUILD_TYPE) + set(CMAKE_BUILD_TYPE "Release") +endif() set(QT_USE_QTOPENGL TRUE) set(CMAKE_AUTOMOC ON) -- 1.8.4

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python rtlsdr for android ?
by william hatch 19 Jan '14

19 Jan '14

I have been trying to install pyrtlsdr from https://github.com/roger-/pyrtlsdr using the librtlsdr shared libraries from https://github.com/keesj/android-rtlsdr . So far the python code installed under /mnt/sdcard/sl4a/scripts is unable to find the librtlsdr shared libraries installed in /data/data/local with that location appended to sys.path. My objective is to access and control the USB SDR tuner directly from my python code without relying on the TCP server. Any help or hints welcome.

2 2

Elonics 4000 bandpass
by Nikos Balkanas 19 Jan '14

19 Jan '14

Hi, I would like to use my E4k dongle for wider spectrum analysis. Currently the tuner is very specific to a frequency. Is there a way to widen its bandpass filter? I have noticed some filters in src/tuner_e4k.c: Mixer filter, IF RC filter and IF channel filter. Are they of any use? Is there a librtlsdr API? TIA, Nikos

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