From: MarkusVester@aol.com
Message-ID: <94.ffdecc5.27b8a16f@aol.com>
Date: Sun, 11 Feb 2001 21:16:15 EST
Subject: LF: Very large adaptive rx array
To: rsgb_lf_group@blacksheep.org
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Hi group,

is there more you can do with that CW carrier-component than simply detect 
the presence of a signal without being able to decode it? Well, we could use 
it to guide a large adaptive array to regain the data rate:

- 100 receivers in different locations across Europe record audio files of a 
highly desired DX-station transmitting 3 s qrss, buried -10 dB in the noise,

- offline, we extract the frequency offset and phase of the DX carrier 
components in each file using low bandwidth (e.g. 3 mHz). We also estimate 
their signal-to-noise ratios;

- using this information as a phase reference, we convert each file to 
baseband (like in a synchronous AM-detector),

- then add up the baseband data from all files, weighted by their SNR. Using 
the carriers as pilots, we effectively have focused our large sparse array on 
a small area around the transmitter, gaining some 20 dB in signal to noise 
ratio,

- and we finally extract the information at full data rate in its original 
0.3 Hz bandwidth, saving a factor of 100 in time and transmitted energy.

Just a thought after a glass of wine, or maybe good for something?
 
73s de Markus, DF6NM