RTL2832U based software defined radios


RTL2832U-based DVB-T dongles are now supported by Gqrx SDR, see this announcement!


You may have noticed the recent buzz on the internet about using cheap DVB-T dongles as software defined radio receivers. It all started on this mailing list when V4L/DVB kernel developer Antti Palosaari discovered that the ezcap EzTV 668 DVB-T/FM/DAB USB dongle, which is based on the RTL2832U chip, can be used to stream raw I/Q samples to the host computer. It is in fact the way the device supports FM and DAB reception; raw I/Q is sent to the host where the application does the demodulation.

Once this was discovered it didn’t take long before Steve Markgraf of OsmoSDR created the rtl-sdr package that could be used to tune the dongle and dump I/Q data do a file for post processing. A few weeks late later Balint Seeber could announce the existence of an rtl_source_c GNU Radio block in his gr-baz package.

Obviously, I had to get one myself.

I followed the link on the OsmocomSDR page and ordered a few pieces from Dealextreme. I got an email on March 22 saying that order has been created and payment confirmed but nothing since then. Anyway, since I have a natural born suspicion against sites with such bombastic names, I decided not to rely on a single source and tried to order a dongle from another place. Thanks to @uhf_satcom I found out that CosyCave also sells the EzTV 666 and at £9.50 incl. VAT it is even cheaper than the $20, to which I will have to add about 150% duties and VAT. Okay, I admit that a web shop that sells herbs, medicine and a DVB-T dongle is not much less fishy than something called Dealextreme… but I can tell you now that they shipped very fast and since it came from the UK I have received it within 4 working days.

EzTV 666 USB DVB-T dongle

It is really amazing how much crap you get for £9.50: A DVB-T dongle, antenna, remote control and even a CD with software:

EzTV 666 package contents

Finally, a few close-ups of the dongle:

EzTV 666 close-up

EzTV 666 close-up

EzTV 666 close-up

As you can see the EzTV 666 comes with the Elonics E4000 tuner chip. As you can see there is not much info about this tuner besides some basic properties and a generic block diagram of a direct conversion I/Q demodulator.

E4000 block diagram

The RTL2832U seems to be more common than one would think. About a year ago I bought a DVB-T dongle in a local supermarket here in Denmark. The brand is called AGK and it worked well on windows but I never got it to work under Linux so I threw it in a drawer where it has been until now. I decided to open it up and take a look at what is inside.

AGK DVB-T dongle

Surprise, surprise! An RTL2832U chip:

AGK DVB-T dongle also uses RTL2832

The tuner, however, is something called FC2580 from a Korean company called FCI:

AGK DVB-T dongle used FC2580 tuner

As with the E4000, there is not much data available but is appears to support similar frequency range, i.e. cover both VHF and UHF up to 1.7 GHz. Once I get my EzTV 666 (and 668?) working, I will also try this one. It does look like I am not the only linux hacker interested in the RTL2832U+FC2580 combination, see for example this repository on Github.

In the meantime there is a compatibility list in progress over at Reddit.