Rtl-sdr » History » Version 11
steve-m, 02/19/2016 10:51 PM
1 | 1 | steve-m | [[PageOutline]] |
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2 | = rtl-sdr = |
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4 | 11 | steve-m | 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. The possibility of this has been discovered by the V4L/DVB kernel developer [http://thread.gmane.org/gmane.linux.drivers.video-input-infrastructure/44461/focus=44461 Antti Palosaari]. |
5 | 1 | steve-m | |
6 | == Specifications == |
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8 | 2 | steve-m | 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). |
9 | 1 | steve-m | |
10 | == Supported Hardware == |
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12 | So far, the following devices are supported: |
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14 | 8 | steve-m | * 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]) |
15 | 1 | steve-m | * Terratec NOXON DAB/DAB+ USB-Stick (Fitipower FC0013 tuner) |
16 | 2 | steve-m | |
17 | 1 | steve-m | Other sticks based on the RTL2832U might be added in the future as well. |
18 | 5 | steve-m | |
19 | This is the PCB of the ezcap-stick:[[br]][[br]] |
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20 | [[Image(ezcap_top.jpg,50%)]][[br]] |
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21 | More pictures can be found [http://www.steve-m.de/pictures/rtl-sdr/ here]. |
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22 | 2 | steve-m | |
23 | == Software == |
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25 | 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. |
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27 | The code can be checked out with: |
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28 | {{{ |
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29 | git clone git://git.osmocom.org/rtl-sdr.git |
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30 | }}} |
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32 | It can also be browsed on http://cgit.osmocom.org/cgit/rtl-sdr/ |
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34 | === Building the software === |
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35 | To build it, simply run 'make' in the src/-directory and make sure you have libusb1.0-0-dev installed. |
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36 | |||
37 | === Usage === |
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39 | Example: To tune to 392.0 MHz, and set the sample-rate to 1.8 MS/s, use: |
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41 | {{{ |
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42 | ./rtl-sdr /tmp/out.bin -s 1800000 -f 392000000 |
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43 | }}} |
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45 | 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). |
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46 | |||
47 | === Known problems === |
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49 | * 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. |
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51 | == Using the data == |
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53 | 3 | steve-m | To convert the data to a standard cfile, following GNU Radio Block can be used:[[br]] |
54 | [[br]][[Image(rtl2832-cfile.png)]][[br]][[br]] |
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55 | 2 | steve-m | 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]. |
56 | 6 | steve-m | |
57 | 9 | steve-m | What has been successfully tested so far is the reception of [http://tetra.osmocom.org/ TETRA] and [http://gmr.osmocom.org/ GMR]. |
58 | 6 | steve-m | [[br]][[br]] |
59 | [[Image(rtl-sdr-gmr.png)]][[br]] |
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60 | Multiple GMR-carriers can be seen in a spectrum view with the full 3.2 MHz bandwidth (at 3.2 MS/s). |