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Rtl-sdr » History » Revision 8

Revision 7 (steve-m, 02/19/2016 10:51 PM) → Revision 8/198 (steve-m, 02/19/2016 10:51 PM)

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 = rtl-sdr = 

 DVB-T sticks based on the Realtek RTL2832U can be used as a cheap SDR, since the chip allows transferring the raw I/Q samples to the host, which is officially used for DAB/DAB+/FM demodulation. 

 == Specifications == 

 The RTL2832U outputs 8-bit I/Q-samples, and the highest theoretically possible sample-rate is 3.2 MS/s, however, the highest sample-rate without lost samples that has been tested so far is 2.8 MS/s. The frequency range is highly dependent of the used tuner, sticks that use the Elonics E4000 offer the best range (64 - 1700 MHz). 

 == Supported Hardware == 

 So far, the following devices are supported: 

  * ezcap EzTV668 USB 2.0 DVB-T/DAB/FM stick (Elonics E4000 tuner) (sources: [http://www.aliexpress.com/product-gs/486876635-DVB-T-Digital-TV-USB-Dongle-Stick-With-FM-DAB-DAB--wholesalers.html AliExpress], [https://www.dealextreme.com/p/dvb-t-digital-tv-usb-dongle-stick-with-fm-dab-dab-44326 Dealextreme]) 
  * Terratec NOXON DAB/DAB+ USB-Stick (Fitipower FC0013 tuner) 

 Other sticks based on the RTL2832U might be added in the future as well. 

 This is the PCB of the ezcap-stick:[[br]][[br]] 
 [[Image(ezcap_top.jpg,50%)]][[br]] 
 More pictures can be found [http://www.steve-m.de/pictures/rtl-sdr/ here]. 

 == Software == 

 rtl-sdr is a commandline tool that can initialize the RTL2832, tune to a given frequency, and record the I/Q-samples to a file. 

 The code can be checked out with: 
 {{{ 
 git clone git://git.osmocom.org/rtl-sdr.git 
 }}} 

 It can also be browsed on http://cgit.osmocom.org/cgit/rtl-sdr/ 

 === Building the software === 
 To build it, simply run 'make' in the src/-directory and make sure you have libusb1.0-0-dev installed. 

 === Usage === 

 Example: To tune to 392.0 MHz, and set the sample-rate to 1.8 MS/s, use: 

 {{{ 
 ./rtl-sdr /tmp/out.bin -s 1800000 -f 392000000 
 }}} 

 If the device can't be opened, make sure you have the appropriate rights to access the device (udev-rules, or running it as root). 

 === Known problems === 

  * If the samples are written to a harddrive, and not a ramdisk, samples may get dropped. An improved version with proper buffering and asynchronous usage of libusb is in the works. 

 == Using the data == 

 To convert the data to a standard cfile, following GNU Radio Block can be used:[[br]] 
 [[br]][[Image(rtl2832-cfile.png)]][[br]][[br]] 
 The GNU Radio Companion flowgraph (rtl2832-cfile.grc) is attached to this page. It is based on the FM demodulation flowgraph posted by Alistair Buxton [http://thread.gmane.org/gmane.linux.drivers.video-input-infrastructure/44461/focus=44525 on this thread]. 

 What has been successfully tested so far is the receiption of [http://tetra.osmocom.org/ TETRA] and [http://gmr.osmocom.org/ GMR]. 
 [[br]][[br]] 
 [[Image(rtl-sdr-gmr.png)]][[br]] 
 Multiple GMR-carriers can be seen in a spectrum view with the full 3.2 MHz bandwidth (at 3.2 MS/s).
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