[R-390] BPL used during WWII?

[John KA1XC]

I've heard of this WWII system but don't think BPL is an accurate term to
use in this instance as it did not transmit multi-megahertz data bandwidth
or use a  frequency hopping or spread spectrum system as does BPL.

John

----- Original Message ----- 
From: "Harry Joel" <hcjoel at direcpc.com>
To: <rbethman at comcast.net>; <r-390 at mailman.qth.net>
Sent: Sunday, July 11, 2004 1:03 PM
Subject: [R-390] BPL used during WWII?


> The ongoing discussion of BPL and its ramifications has intrigued me much.
It appears that the German equivalent (up to a point) of Homeland Security
had designed installed a warning system used during pending bombing attacks
by Allied airforces near the end of WWII. I have seen this system in
operation, but must admit that I have little information about what
frequencies were used. As all AM (no FM back then) stations went off the air
to prevent them to be used as beacons with RDF equipment aboard the bombers
and Pathfinders (ahead of the bomber squadrons) civilians had no early
warning system about what to expect and take to shelters as needed.
> The system transmitted voice messages via power lines to anyone using a
free decoder box placed near an AM receiver. The decoder box received voice
data from the wall outlet. A map came with the decoder box. The alerts
always refered to a set of co-ordinates on these maps wich covered a few
hundred miles in each direction from home base.
> A typical transmission would go like this:
> "Approximate 400 planes in A-5 heading southwest" and may be a shortly
after
> "Turning  west and entering B-4"
> Quite often these alerts kept track of more than one array of bombers. The
turns were often an attempt to disguise the ultimate target.
> I have done a Google search but could not locate any reference to this
early BPL system used by the Germans.
> I also read the info on
http://www.arrl.org/tis/info/HTML/plc/bpl-deployment.html
> to gain some insight for a possible comparison.