[FedCom] FBI Radio Systems Keyups?

[Tom Greenwood]

Thanks, Tom

That has been pretty much what I have observed here.  Various machines over
the year have been susceptible and notorious for doing this.  My suspicion
has been that they are most likely located at the various tower farms where
the background RF noise tend to be high.

It was very interesting in the 80's when the FBI decided that they were
going to reverse the input/output relationships all their repeaters.  One
machine would key up on the new output frequency which was the old input
frequency for repeaters elsewhere.  All the machines whose old input was the
same as the new output would then key up and would be transmitting their
output on the new input frequency.  The system would lock up for hours like
that.  Was quite interesting to hear feedback over a 25 to 50 mile path.
Eventually, all of the machines were retuned and the problem went away.

73's

Tom


-----Original Message-----
From: fedcom-bounces at mailman.qth.net
[mailto:fedcom-bounces at mailman.qth.net]On Behalf Of Tom ND5Y
Sent: Saturday, March 22, 2008 19:48
To: Discussion of Federal Government Communications
Subject: Re: [FedCom] FBI Radio Systems Keyups?


Yes. All I could see was the PL tone. In my area it appears that this is
 just some type of interference or noise that occasionally falses the
PL decoder, or something in whatever they use to link everything together.

Tom

Tom Greenwood wrote:
> Has anybody made any attempts at looking at the transmissions using an
audio
> spectrum analyzer such as the program Spectrogram to see if there are any
> subaudible data transmissions?  I have used this program in the past
looking
> at data transmissions with very interesting results.  As I recall, the old
> 414/419 links were rather revealing once looked at this way.
>
> 73's
> Tom, N1JQB
> Metro West Boston


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