Advanced Beacon concept

hal feinstein hfeinstein at
Sun Sep 2 09:38:29 CDT 2007

At taco a few of us have been batting around the idea of an advanced  
beacon design based on JT65.

A paper by Andrea  Dell'Immagine  IW5BHY suggests an advanced beacon  
using slow CW and a correlation
receiver. The receiver is, in some ways, similar to one of  Andre's  
( N4ICK) DS spread spectrum receivers, using
a disciplined time base derived from a broadcast station (RAI).  The  
signal is split  into I and Q channels that
are applied to a correlation stage. The LO is critical and must match  
frequency within a a few milliHERTZ (mHz)
The time base is used to create a precise LO frequency.  I and Q  
channels handle phase differences between the
signal and the LO.  Receiver performance yields signals recovery with  
SNR around -40dB.   Listening to a -40dB
signal by ear you can just about make out that a signal is probably  
present.  Its too weak to hear much else.

Toward the end of the paper is listed a few of the merits of a beacon  
receiver with this design

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