[Scan-DC] Russian Numbers station broadcasting spike

[sdaitch at kuw.ibb.gov]

There is one explanation which may or may not fit the 
situation for which you are asking.

Many years ago, the VOA facility at Greenville had several
Kahn and a few home built modulation systems which allowed
exactly that modulation scheme.  We used them with the 
no-longer installed Gates HF-50C transmitters (GA-7 through
GA-9 and GB-7 through GB-9), so we could operate these AM
transmitters in the utility frequencies.  

Apparently we could not use the utility frequencies for 
standard AM, but we could suppress one sideband and still
transmit full carrer and one sideband.  The irony is we could
use ISB on the utility frequencies, which was the same 
bandwidth as an AM signal.  

We were using the ISB transmitters and the few scheduled
Kahn system operations for program feeder service for our
overseas transmitter stations, before we converted the feed
network from HF to a satellite based distribution network.

We had need for more feeder circuits than we had available
with the two TMC ISB transmitters at each site.

This might be one technical article on the equipment:

http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F10933%2F4065481%2F04065497.pdf%3Farnumber%3D4065497&authDecision=-203

I am not an IEEE member, so I can't look at it, but the timeframe
seems appropriate, as VOA was using the Kahn equipment into the
late 1970s.

73
Sheldon
WA4MZZ


----- Original Message -----
From: Blair Thompson <b_thom at juno.com>
Date: Friday, December 17, 2010 5:47 pm
Subject: Re: [Scan-DC] Russian Numbers station broadcasting spike

> What's the point of AM suppressed lower sideband? You still have 
> to waste power on sending the carrier? The bandwidth is narrower, 
> but why not just send USB? Are listeners not able to provide 
> synchronous detection?
> 
> Maybe there is no explanation. Thanks.
>