It was recently discovered that several cheap DVB-T usb dongles could be configured to be used as cheap ham radio receivers. 
Follow along with the discussions here: http://www.reddit.com/r/rtlsdr or find some of the useful software here: http://sdr.osmocom.org/trac/wiki/rtl-sdr

 picked up one of the compatible receivers from ali-express:

and will document here the steps I took to set it up with gnuradio on ubuntu 12.04.

There are a few things that I won't cover in this instructable, because they deserve an instructable of their own. These include:

1) using the Ubuntu command line (terminal)
2) cloning a git repository
3) building software from source on Ubuntu (especially with cmake)

If anyone has links to stellar, class A++ quality tutorials on any of these things, please add them to the comment and I will link them here.

Step 1: Install Gnu-radio

It looks like there are two options for installing an up-to-date gnuradio on ubuntu:

1) use an install script
2) install from source

Don't ask me why, but I tried the second option (probably the harder). After a first attempt that failed, I went for the first (and recommended option) to much success! So... lesson learned. Note to self, follow advice of program developers when installing software.

My advice, use the install script. 

Step 2: Install Rtl-sdr Tools

Next, you want to install any missing rtl-sdr specific tools from here:

Again, rather than duplicating instructions, follow the steps outlined here to install the rtlsdr library & capture tool: git://git.osmocom.org/rtl-sdr.git

Although this page also mentions a gnu radio module (git://git.osmocom.org/gr-osmosdr) I was unable to get it to work. Instead, I installed:

as recommended from here: http://2h2o.tumblr.com/

the basic steps are:

git clone https://github.com/balint256/gr-baz
cd gr-baz
sh bootstrap
sudo make install
sudo ldconfig

Now you should have all the necessary software to communicate with the DVB-T dongle using gnuradio.

Step 3: Setup Udev Rules

Next, you need to add some udev rules to make the dongle available for the non-root users. First you want to find the vendor id and product id for your dongle.

The way I did this was to run:


The last line was the Realtek dongle:
Bus 001 Device 008: ID 0bda:2838 Realtek Semiconductor Corp.

The important parts are "0bda" (the vendor id) and "2838" (the product id).

Create a new file as root named /etc/udev/rules.d/20.rtlsdr.rules that contains the following line:

SUBSYSTEM=="usb", ATTRS{idVendor}=="0bda", ATTRS{idProduct}=="2838", GROUP="adm", MODE="0666", SYMLINK+="rtl_sdr"

With the vendor and product ids for your particular dongle. This should make the dongle accessible to any user in the adm group. and add a /dev/rtl_sdr symlink when the dongle is attached.

It's probably a good idea to unplug the dongle, restart udev (sudo restart udev) and re-plug in the dongle at this point.

Step 4: Test It Out

Now, plug in the dongle and run the following command to test out rtl-sdr:

rtl_sdr capture.bin -s 1.8e6 -f 392e6

Ctrl-C the program after a second or so. If you saw no errors, you should see a file named capture.bin in your current directory. If the program complains about not being able to open the device, try sudo-ing the command. If that helps, the udev rules are probably incorrect.

If all is still going well, try out the attached rtl.grc gnu-radio graph by downloading it and opening it with:

gnuradio-companion ~/Downloads/rtl.grc

It is a modification of the graph from http://2h2o.tumblr.com/ to use a pulse audio (Ubuntu default) rather than an ALSA audio sink.

If you've reached this point with no errors, you are now as far as I am :)

Enjoy! and please add any resources you have on using gnuradio to the comments.
<p>As of Ubuntu xenial (16.04LTS) gnuradio has made it in to the APT repositories. This makes it a little easier to install in Ubuntu. Use the following command line: sudo apt-get install gnuradio</p>
<p>While installing the GNU radio from the script it does not go ahead of &quot;Done checking packages&quot; message. what can I do about this?</p>
There's a nice Ubuntu remaster called &quot;Skywave Linux&quot; with plug and play RTL-SDR support.<br><br>http://skywavelinux.com<br><br>It has some other apps as well, but CubicSDR runs right out of the box, and the dreaded kernel driver dvb_usb_rtl28xxu is blacklisted by default.
<p>when i run the command sh bootstrap i get an error sh: 0: Can't open bootstrap. pls suggest me a solution?</p>
I'm new to SDR radio (Software Defined Radio) and have no idea what &quot;RTL&quot; is and have no idea what &quot;gnuradio&quot; is too. <br> <br>OK, I went digging and found this: <br>http://en.wikipedia.org/wiki/GNU_Radio <br> <br>Is RTL a reference to the Realtex USB DVB-T receiver?
<p>Yes, that is the one. Is just a cheap receiver up to 2.1 GHz. </p>
Correct! <br> <br>It comes from the part name. See here: <br>http://sdr.osmocom.org/trac/wiki/rtl-sdr
Thanks for that website, it is packed with information. I found a Realek DVB-T for only $20 and I've got the software now. Thanks for your assistance.
<p>Great tutorial, thanks for sharing it. I have two comments that might make it easier for others. <br><br>First, I had some problems, like you had, installing gr-osmosdr, but I found out that you can install it by just doing &quot;sudo apt-get install gr-osmosdr&quot; I think is easier to install than gr-baz if you don't have npm or any of the other framework dependencies.<br><br>Second, I added a WX GUI Text Box to your rtl.grc to set the frequency so you can tune to other FM stations without stopping the application. Basically you give it a name to the Text Box and instead of typing a number in the Frequency field in the RTL-SDR Source you type the name of the Text Box</p>
Great instruction I'we allmost made it,<br> <br> I was able to come to step four in braingram's instruction and with success test out the rtl-sdr with &ldquo; rtl_sdr capture.bin -s 1.8e6 -f 392e6 &ldquo; . Continuing stresses my limited Linux capabilities.<br> <br> The instruction is : &ldquo; If all is still going well, try out the attached rtl.grc gnu-radio graph by downloading it and opening it with: gnuradio-companion ~/Downloads/rtl.grc &ldquo;<br> <br> I have three problems:<br> 1) Downloading. I can see the attachment (rtl.grc 9KB) but trying to copy/paste it into downloads gives no result.<br> 2) Opening. I can open the attachment by clicking it but it opens as a text file.<br> 3) Finding. Searched the file system but cannot find anything that resembles &ldquo;gnu-radio-companion ~/Downloads/rtl.grc&rdquo;.<br> <br> Would greatly appreciate if someone knowledgeable could give me a friendly push in the right direction.<br> <br> RolfV
On Ubuntu 12.10 64-bit, I get the error below, but gnuradio-core seems to be not available for 12.10. <br> <br>Tips? <br> <br> <br> <br>checking for GNURADIO_CORE... configure: error: Package requirements (gnuradio-core &gt;= 3) were not met: <br> <br>No package 'gnuradio-core' found <br> <br>
Thanks for these instructions. The auto build script didn't work for me. I think I might have confused the git checkout with some other directories in the same dir. <br> <br>I have to say, setting up sdrsharp (sdr#) on win32 was a lot easier, though it did involve copying over the rtl-sdr library as well. <br> <br>Now I'm searching for a scanner than can go through all the frequencies automatically, <br>or an interface for linux as simple as sdr#, which I think might be linrad. <br> <br>Note that ettus has binaries of just the gnuradio bit dev version and I think now those will support rtl-sdr too if you want to speed up the process.
If you need a real guide for setting this up... http://www.thepowerbase.com/2012/06/getting-started-with-rtl-sdr/
Thanks for sharing this. I have been having the build-gnuradio script barf with the error &quot;you do not appear to have the 'rtl-sdr' directory. <br> <br>Do I just move on to step 2 of your instructions since that also appears to involve rtl-sdr tools?
Cool. <br>

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