Dan Andersson wrote:

Mike wrote:


Hello,
has anyone come across any projects or info on building your own DAB
radio.

This is my (limited) understanding:

How it's sent: The audio (or whatever) signal is split and sent using
Quadrature Amplitude Modulation over many narrow band carriers (each
carrier at a different frequency): Ie it's spread spectrum. Error
correction Coding is also used, etc.
To decode it: This is where I'm confused; Can I build a receiver which
will receive the whole collection of narrow band carriers, then feed it
into a computer that will do some FFT?

Not really sure how to move forward; any ideas would be fantastic.

Thankyou all!

(PS It's good to see there's a newsgroup on this topic).

Mike Smith




Mike,

Look at the converter boards suitable for GnuRadio (DRM). They use fast
chips from Analog Devices and you can see the whole design and schematics.

This will give you a good hint on what's needed. Remember that darned Mr
Nyquist! You really need the speed!

A good way forward while building the conversion block is to initially use
GnuRadio for verification before you start coding with a PIC.

DRM uses a significantly lower bandwidth than the spec the OP linked to.
In fact, you can implement a DRM demodulator in software on a PC. I
wouldn't take anything that works with DRM as an indicator for what
hardware you'd need for the DAB format he's interested in.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com