[BC] GWEN system...

[Broadcast List]

The GWEN (Ground Wave Emergency Network) station at WXTR (FM) in  
Waldorf, MD had two equipment shelters on the WXTR property, one  
containing the radio and computer equipment, and one containing a  
generator, and a 406 MHz corner reflector about 100 feet up the (old)  
tower pointing to Andrews Air Force Base.  That link was AX.25 using  
a simple UHF FM transmitter.  It wasn't very active.  The VLF antenna  
was maybe 1/4 mile away on someone else's land.  It was fed from the  
equipment shelter via 1-5/8" coax in buried in conduit.  The tower  
lighting ran in another duct in the same conduit.  A wide piece of  
strap was buried along side the conduit.  When I built the new tower  
the foundation was very near the conduit, so we hand dug to the strap  
and bonded to it.  I think that is why that tower takes many repeated  
lightning hits and never has any problems.  In fact, I later  
discovered that "tourists" sit in the driveway to watch lightning hit  
the towers.  Amazingly, lightning would bypass the tall tower and hit  
the smaller ones about 1/3 of the time.

To not answer the second question, while the UHF link used 1200 BAUDS  
AX.25, I have no idea what the VLF link used.  I understand it was  
incredibly slow.  The network was configured so that one VLF station  
would link to the next, then that one to the next and so on.  It was  
never envisioned that any of the stations would fail, or be taken  
out, so there was no plan for longer range links.  The technicians  
found that the system would bypass intermediate stations, halving the  
time it took to send a message.  They called this "skip" even though  
it was still ground-wave.

I had a funny experience with their inept maintenance technicians.   
One smelled of Bourbon, but a call to the Corps of Engineers put an  
end to that.  He never bothered to spin the combinations on the locks  
-- idiot.  None of them seemed to be able to fix anything.  I had one  
ask for a tour of the FM transmitter site.  Sure.  But, he would not  
let me see his stuff.  He said it was classified.  Funny thing was  
that when he was unable to fix something he was more than willing to  
let me in.  Very sad.

On Oct 1, 2007, at 5:26 PM, broadcast-request at radiolists.net wrote:

> Message: 5
> Date: Mon, 1 Oct 2007 06:42:57 -0600
> From: "Gary Peterson" <kzerocx at rap.midco.net>
> Subject: [BC] GWEN system...
> To: <broadcast at radiolists.net>
> Message-ID: <000501c80428$9824ca50$c86e5ef0$@midco.net>
> Content-Type: text/plain;	charset="iso-8859-1"
>
> " FWIW, back in the 80's we used to lease land at the old WXTR-FM  
> tx site
> in Waldorf, MD to the Army for a GWEN station.  Maybe Eddie or Chip  
> have
> photos to share.  All my stuff is boxed up in storage.
> Wonder what its status is today?
> G "
>
> While listening for signals in the experimenters' band, back  
> sometime in the
> 80s, I remember hearing very strong signals on VLF.  They sounded like
> several mechanics dueling with air hoses in a large garage.  The S  
> meter
> would kick way up and the speaker would emit a loud hiss, then  
> silence, then
> another hiss with a different signal strength and a different  
> timbre, then
> another hiss, sometimes overlapping a previous hiss.  I surmised it  
> was
> digital data of some sort coming from multiple sources.  Many  
> others in the
> area heard the same signals.  Someone suggested it might be  
> something called
> "GWEN."  Does this sound like the type of modulation that was used  
> by GWEN
> VLF stations?  I haven't heard it for many years now.
>
> Gary, KØCX
> CE KFXS, KOUT, KKMK, KRCS, KKLS & KBHB
> Rapid City, SD