[GreenKeys] FSK on WABC

Wed Dec 2 22:09:13 EST 2009

I remember reading on one of the lists about FSK on WABC several years ago. About propagation to the Carribean
: As a child of maybe 7 or 8,our family took a holiday vacation on a tiny island called Harbour Island in the Bahamas just off the island of Eluthera. This would have been 1959 or 1960.As little tourist kids,my brothers and sisters and I wandered around the tiny town exploring the wonders of impoverishment.Well, on one ocassion we came across a bungalow and the folks gathered outside were listening to a table radio blasting WABC.This was in the morning and it was clear with no fading at all.We were all amazed ( at least the older three of us that actually new WABC since thats how we heard about our "snow days" back then). Asked Dad about it and he explained what he knew about propagation  and how we were in the Bermuda Triangle and strange things happen.I have many vivid recollections of that trip but the most imprinted one is of flying in the co-pilot seat of the Grumman Goose the took us from Nasau to Harbour Island.I remember flying over water so clear that you couldn't see it.The bottom of the sea looked like you were over land.It's no wonder those TBM's were lost.One certainly had to get used to the orientation/dis-orientation of flying over such clear flat shallow seas.
 No,I don't remember any radios on that plane,I had not yet built my Cub Scout crystal radio kit that got me started on this path.
 Jay

-----Original Message-----
From: David I. Emery <die at dieconsulting.com>
To: Richard Dillman <ddillman at igc.org>
Cc: greenkeys at mailman.qth.net
Sent: Tue, Dec 1, 2009 8:26 pm
Subject: Re: [GreenKeys] FSK on WABC

On Tue, Dec 01, 2009 at 12:44:23PM -0500, Richard Dillman wrote:
> One assumes it was for submarine communications but I wonder if anyone
 has any further details.
    I have read some comments - I believe including some
eclassified official document references - to a program involving
SKing of clear channel AM broadcast transmitters in the SE that put
ood signals into Cuba having been used by the CIA to communicate with
peratives inside Cuba around the time of the Bay of Pigs fiasco.  I did
ot see any particular technical details of the actual modulation
arameters - either analog or digital (eg baud rate and codes used).
    Apparently some US clear channel AM stations put walloping huge
ignal into parts of Cuba and someone came up with the idea of taking
dvantage of it... what they used for receivers in the field was not
iscussed either, however...
    I have also seen documents about the RTTY FSK being discussed
ere - I believe it was intended as a kind of short term quasi
evelopmental precursor to the GWEN LF ground wave network that was
mplemented widely across the US by sometime in the late 70 - or 80s and
ept around until it was mothballed after the  end of the cold war (and
hen some sites converted into DGPS stations rather than torn down).
    It was realized that ground wave propagation at LF and BC
requencies was pretty effective in a disturbed propagation environment
uch as might exist peri and post nuclear attack and might provide a
seful backup comms channel.   That certainly was the notion with the
WEN system (which used a higher data rate in a packet type format on LF
requencies around 170-190 KHz).
    I also remember actually noticing the FSKing of a couple of
owerful local AM stations back in the late 60s and attempting to copy
t - I have no recollection of being able to recover anything much in
he clear - it is possible I recovered a RYRY / FOX test once, not sure
 remember any other details - but I definitely was not able to get good
nough copy to find any regular actual traffic there and I know the
irst few times I heard it I though I was hearing problems with the
eceiver stability rather than something real.

- 
 Dave Emery N1PRE/AE, die at dieconsulting.com  DIE Consulting, Weston,
ass 02493 "An empty zombie mind with a forlorn barely readable
eatherbeaten 'For Rent' sign still vainly flapping outside on the weed
ncrusted pole - in  celebration of what could have been, but wasn't and
s not to be now either."
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