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From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: How does a mixer work?
References: <email@example.com> <firstname.lastname@example.org>
Date: Wed, 23 Oct 2002 00:18:13 GMT
NNTP-Posting-Date: Tue, 22 Oct 2002 17:18:13 PDT
> John fields posted:
> << I don't know if it's old hat, but a method I worked out in the '60's
> was to send a 1kHz signal and then have the far receiver tune its
> VFO until the radio's audio output was precisely 1kHz. >>
> I'm sure some operators probably did that manually. I am still surprised that
> using reduced carrier level did not gain general favor. Under most received
> signal conditions, a carrier attenuated by 20 dB or so would have been usable
> for sync in a ssb system even with 1950's technology..
Why bother when you can synthesize the transmitted frequency and the
receiver can synthesize the LO and the carrier to reinsert all quite
easily. This was old technology when I encountered it in 1966. If you
can easily agree with the distant end and have a channel by means of
which this agreement can be reached, there is no point in a carrier. Of
course, HF communication run in this way has all but vanished but at one
time, it was the most important stategic communication system that the
US military had available. It used perhaps a hundred stations having 10s
of high power transmitters each. The site I worked at had 65 such
transmitters some 50 or so of which would be in operation at one time.
(We were a delite to local oil companies because of the insatiable
appetite of the power plant for diesel fuel. 2.5 megawatts or so takes a
little oil to produce 24/7.)
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons email@example.com
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