RTL-SDR: Quick Guide to Software Defined Radio on Mac OS X Yosemite

Today another little package from China waited in my inbox: a DVB-T+FM Tuner. So far not that exciting. Except that this package for $10.99 is capable of receiving a huge spectrum of 24-1766MHz thanks to the powerful tuner inside.

The keyword for making this hardware useful is Software Defined Radio or short SDR. And since the hardware is based on the Realtek Chip RTL2832U the software supporting it is called RTL-SDR.

I kind of expected an annoying process of getting it to run on Mac OS X Yosemite (10.10) but it turns out it was very easy. Just follow these steps.

1. Get the Hardware

I ordered mine from Banggood and it arrived in about 3 Weeks from China to Europe. You can of course buy it anywhere. Just make sure that the device contains a RTL2832U chip.

2. Install the Software

Because I’m a Mac user I will show you how to install GQRX, an excellent software running on Linux and Mac OS X. But you can also easily find excellent software for Windows. I hear that SDR# is a very nice tool, but I didn’t have the chance to use it yet.

Install the latest version of MacPorts from here. If you are not a coder you will probably also have to install XCode from the AppStore
When the installation has finished, open a new terminal window and execute
```
sudo port install gqrx
```

Warning: this might take I while. On my not-so-young MacBook Pro it took about an hour…
After the installation has finished, plug in the tuner and test it by executing:

rtl_test -t

Giving me this this output:

Found 1 device(s):
  0:  Realtek, RTL2838UHIDIR, SN: 00000001

Using device 0: Generic RTL2832U OEM
Found Rafael Micro R820T tuner
Supported gain values (29): 0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6 
Sampling at 2048000 S/s.
No E4000 tuner found, aborting.

which looks good!

3. Run GQRX

Now that you hopefully have a running gqrx. Execute it from the command line:

gqrx

In the following screenshot I’m tuning in on my garage door opener:

gqrx on Mac OS X Yosemite Tuned in
on a Garage Door Opener

Summary

With just a few steps and the right hardware you can get a powerful tool to listen to all kinds of radio frequencies. You can for instance also find software that can read out the transponder data of commercial airplanes, a protocol called ADS-B. This will be one of my next experiments with RTL-SDR