[linux-audio-dev] Re: Radio receiver.

[fons adriaensen]

On Sat, Nov 05, 2005 at 09:23:05PM +0200, Juhana Sadeharju wrote:
> 
> Thanks for the tip on "diversity reception". Yes, I got the
> idea from astronomer's systems.

Normally 'diversity reception' means to combine the signals from
2 or more receivers to obtain a result that has a better S/N ratio
(or less missing data) than either of the inputs.

What the astronomers are doing is even more tricky. They combine
signals from distant receivers not to get a better signal but to
improve the angular resolution of the antenna, by 'synthesising'
the effect of a very big one. It's called 'interferometry' and
can get quite complicated.

> My test plan was to record the same music station at two cities
> (apart 200km). Then timescale and align the digitized (1 or 2 hours)
> recordings manually. And then do the thing.

If both recordings are complete and have about the same quality, the
best you can obtain is a 3 dB gain in S/N (for analog transmissions -
for digital the picture is more complicated).

-- 
FA