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Re: [TowerTalk] Original Hygain/Military-Commercial Products

To: Pat Barthelow <>,Chris Pedder <>,,
Subject: Re: [TowerTalk] Original Hygain/Military-Commercial Products
From: Jim Lux <>
Reply-to: Jim Lux <>
Date: Mon, 31 Dec 2007 06:26:44 -0800 (GMT-08:00)
List-post: <>

-----Original Message-----
>From: Pat Barthelow <>
>Sent: Dec 31, 2007 5:57 AM
>To: Chris Pedder <>,, 
>Subject: Re: [TowerTalk] Original Hygain/Military-Commercial Products
>I have often wondered, if the LP design for Military/Embassies, was selected 
>for broadband capabilities, which might be needed if secure  HF comms 
>used/needed spread spectrum modulation, back in the "olden days" of  comms 
>over HF.

More likely, just that there's no need for tuning, and the fact that they can 
run extra power to  make up for the difference in gain over a narrow band 
Yagi-Uda type antenna.

HF spread spectrum systems using direct sequence spreading would typically not 
use a very huge spread bandwidth, because the ionospheric channel isn't all 
that wideband (i.e. if propagation only supports 7.3 to 7.6 kHz, there's not 
much point in transmitting a signal that goes from 4.5 to 10.1 kHz).  A spread 
bandwidth of a few hundred kHz would be typical. (And would still give you a 
process gain of 20dB or so)

A frequency hopper that hopped at, say, the symbol rate, would be moving too 
fast for an autotuner to keep up, so a broadband antenna would be useful there, 

>Someone once told me, that,  long before  Spread Spectrum became familiar in 
>the ham radio vernacular, that  the term "Spread Spectrum" was itself 
>classified, could not even be said openly, among the military/spook crowd.

Probably true, but that would have been 50s, perhaps 60s, era.   R.C.Dixon 
published Spread Spectrum Systems in 1976.  Lots of people were thinking about 
it and discussing it before then. About the time that PLL synthesizers  & 
microprocessors became common, it became possible to do FH fairly easily, and 
there were a number of "retrofit" FH radios around.

Jim, W6RMK

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