[Elecraft] The Old Days

[Sandy]

I was personally in military avionics during the days of the SCR-522 and 
ARC-3 (both VHF).  Later with the Collins ARC-27 and the RCA ARC-34 which 
were both UHF sets (225-400 Mhz.)
I know FM was proposed by some at one time and it was nixed due to the 
"capture effect" and SSB also proposed but nixed due to additional 
complications of tighter frequency stability.  They finally "split" the 
channeling to get more frequency space assignable by using smaller guard 
bands between channels.  I was gone from the military avionics when that 
happened.  In an Air National Guard group flying F-102A's at the time.  They 
are now flying F-15's!

That has been some time ago when everything was vacuum tubes!

73,

Sandy W5TVW

-----Original Message----- 
From: NZ0T
Sent: Tuesday, January 29, 2013 3:58 PM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] The Old Days


The conclusion here may well be part of it.  A coworker who worked in
avionics in a former life told me that the use of AM for aircraft
communications is indeed for the ease of tuning but also because a
weaker station can be heard under a stronger one unlike with FM and its
capture effect (likely true for digital).  AM allows an air controller
or other aircraft to hear an emergency call when another station is
transmitting.  Based on my experience, I have no reason to doubt his
conclusion.

73, de Nate, N0NB >>

Nate, that is exactly the reason AM is still used for aviation.

73 Bill NZ0T (old pilot).



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