The Telecom Digest for December 10, 2010
Volume 29 : Issue 333 : "text" Format
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Date: Thu, 9 Dec 2010 09:49:55 -0800 (PST)
From: Lisa or Jeff <firstname.lastname@example.org>
Subject: Re: Question about an old scrambler phone
On Dec 8, 7:38 am, bon...@host122.r-bonomi.com (Robert Bonomi) wrote:
> One of the simplest forms of a 'scrambler' simply frequency-inverted
> the audio input. basically, use the audio to AM modulate a circa
> 4kHz 'carrier', and send only the the lower sideband over the
When the Bell System introduced overseas communications via radio,
they included frequency shifting as a privacy measure. It was more
designed to prevent inadvertent evesdropping as opposed to stringent
security. They said a person with excellent hearing and skill could
listen the discern the conversation, and of course constructing a
descrambler would not be hard to do.
It's written up in the Bell Labs history.
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