Instructables

RTL-SDR FM radio receiver with GNU Radio Companion

Picture of RTL-SDR FM radio receiver with GNU Radio Companion
RTL-SDR is currently very popular topic on the Net. There are also many guides on how to use it on Windows and Linux too. But starting to use it myself I haven't found any guide that explains whole process from installing necessary drivers and software to building first simple receiver using GNU Radio which is the most capable software which could be used with RTL28xxU chips and that's what this Instructable is about. It should be, for me I hope too, first step to learn how the thing works from scratch and to make projects capable of capturing signals that wasn't decoded using RTL-SDR yet i.e. 433 MHz band.
 
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Step 1: What's RTL-SDR?

If you are interested only in how to make GRC project go to step 5.
RTL-SDR is the cheapest method to get into the world of SDR (Software Defined Radio) - method of receiving (RTL-SDR have no capability to transmit) and processing radio transmission using your PC. Using it you can receive everything that is transmitted between about 20~2000 MHz depending on second chip on the device.
In brief it can hear i.e.:
- ordinary FM radio stations
- police radio transmissions
- plane and ship tracking informations
- small radio devices like car keys
- probably GPS satellites (as of now there is no confirmed method to do this)
- International Space Station and other space equipment that transmits below 2 GHz
- every other device that you know transmits on these frequencies

Step 2: How to get it?

Picture of How to get it?
The simplest method is to get one on eBay. There are many offers that have in their caption names of the chips that are on board. They costs about 10$. Here you need to be aware of few different chips that are currently on market. The difference between them are frequencies they are capable of receiving. Summary of the differences is on that site: 
http://sdr.osmocom.org/trac/wiki/rtl-sdr
The most reasonable choice is R820T chip and that tutorial is based on its capabilities. The other good chip is Elonics E4000 but they are actually more expensive ones.
deadbok7 months ago

Thanks for getting me started with GNU Radio. Great Instructable.

rtl-fm.grc.png
gwenhastings7 months ago

I keep getting error messages about source io size 8 doesnt match sink io size 4 for blocks_multiply_const and for the analog_wbfm_rcv0 with those messages reversed.. dont see a way to alter io size.. what am I doing wrong?

but thanx for an excellent tutorial... some clarification about how to connect block in the flowgraph would have been nice (I know afterwards its obvious but i didnt hunt a bit for a few moments.. for that)...

gwen

Eternal6611 months ago
It's seems cool!