Fwd: Tuesday Tech Net

[Nan and Sandy Sanders]

> From Hal WB3KDU
>
>
>
>Tuesday Tech*Net   8PM AMRAD repeater (21/81) and Echolink.
>======================================================
>
>Built in 1927 SAQ is VLF station operating on 17.2Khz  generating 
>its signal with a
>mechanical Alexandrian generator.  AMRAD members have been DXing SAQ for
>a number of years and some have been the repent of its special QSL which can
>only be obtained by copying accurately most of its transmission.  SAQ operates
>twice a year, Christmas Eve and the first Sunday of July which is 
>rapidly approaching.
>
>There are practical problems to receiving SAQ.  First you need a 
>receiver that
>covers 17.2Khz with adequate sensitivity.   Next, there is a large amount of
>noise to contend with - simple radio static, weather and man-made.  This
>requires a very narrow filter, usually around 50hz to limit the 
>noise. If the signal
>strength is not strong (this happens from time to time) you may be unable to
>hear the transmission or you may discern it but be unable to copy it because
>it is so weak.
>
>Attempts have been made to record and digitally process the signal attempting
>to apply DSP techniques to recover the station's audio.  This hasn't proved
>successful in the past due to various technical issues. However, it 
>might be worth
>trying this route if the signal is too weak to copy by ear.
>
>It also might be possible to have several stations record whatever 
>audio they can
>and then combine a number of recordings made by receiver in different parts
>of the country.  This could be done processing just the audio.   A 
>more ambitious
>idea is to record the RF baseband and combine and process it.   It 
>would require phase
>references to be recorded along with the signal.  It would involve some
>tricky DSP code too.
>
>http://en.wikipedia.org/wiki/Varberg_Radio_Station
>
>Besides SAQ we will have our usual exchange on digital modes and SDR.
>
>Should we sponsor a "Learn Verilog" project of some kind?  This is one
>of the popular languages for programming an FPGA.
>
>Last week we had a couple of station check in so attendance on the net,
>while still small is definitely up.
>
>======================================================
>Tech*Net meets Tuesday 8PM on the AMRAD repeater (21/81) and
>via Echolink on the W4CIA conference point.  WB5MMD is conference
>coordinator and net control.
>