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.

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
<p>I got FM to work fine, any tips on how to do AM? </p><p>I'm trying to listen to 640khz with a rtl-sdr and HamItUp/SpyVerter. The upconverter puts the RF at 125Mhz, so I tune the radio to 125.64e6 (125e6 + 640e3), then pass it to a low pass filter before demodulating and outputting to the sound card. Unfortunately, it doesn't work, any idea what could be wrong? </p><p><a href="http://imgur.com/a/BxBVQ" rel="nofollow">http://imgur.com/a/BxBVQ</a></p>
<p>Anyone know what the audio device path would be for the audio sink running on a raspberry pi?</p>
<p>Worked really nicely! The one thing to note is if you are tuning to an FM frequency, it's in MHz. Meaning 100.3 is really 100.3e6. Also I implemented this with QT GUI options (which is preferred with newer GNU Radio). </p>
<p>Great work... but I think in the Low Pass filter, transition width must be very less. you can choose in between 5k to 10k. Otherwise filtering will not work. </p><p></p><p>Check filter response... </p>
<p>I don't remember what I'd done to install gnuradio and driver for my cheap rtl-sdr device on my mbp, and effort to figure out blocks for version of gnuradio-companion on macport, but finally I can get it work :D </p>
<p>works like a charm, just had to check a couple things but we got 'er done, thanx!</p>
<p>Just a quick heads up: Texts like these are awesome, but they tend to outdate at some point. The official wiki of GNU Radio, <a href="https://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorials" rel="nofollow">www.gnuradio.org,</a> is the place where information on GNU Radio is gathered.<br><br>Generally, to get started, I recommend the continously updated, tested and supported Guided tutorials:<br><br><a href="https://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorials" rel="nofollow">https://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorials</a><br><br>They are not as centric on doing a specific thing with a specific piece of hardware, so this won't get you started as fast doing <em>something</em>, but it will explain the core concepts, so you can do <em><strong>anything</strong></em> pretty quickly!</p>
<p>https://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorial_Hardware_Considerations/62#A-Working-Software-Radio-Broadcast-FM-Receiver is an example FM radio setup from the GnuRadio site.</p>
<p>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?</p><p> 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)...</p><p> gwen</p>
<p>The error message is not meaningful, but it is happening since you have different data types. If you look at the pictures in the instructable above you will notice the &quot;in&quot; &amp; &quot;out&quot; tab colors are half blue and the other half is orange, these colors define the data type such as int, float, complex ...etc and you must match the type on the intput with the output.<br><br>So in your case you need to change the default setting for the rational resampler and multiply const blocks to &quot;float&quot; since the FM receiver output is float, and the audio sink input is also float.</p>
<p>Thanks for getting me started with GNU Radio. Great Instructable.</p>
It's seems cool!

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