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Re: [TenTec] Orion II manual / firmware for 565 / 8P with Orion II

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] Orion II manual / firmware for 565 / 8P with Orion II
From: Sinisa Hristov <shristov@ptt.yu>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Thu, 16 Feb 2006 01:58:44 -0500
List-post: <mailto:tentec@contesting.com>
"Martin, AA6E" wrote:

> In any case, the same clock oscillator seems to be used for the Master
> and Sub CODEC in the Orion 1.

Yes, it's the same oscillator, but it's not used the same way.

On both receivers, the received frequency is a weighted sum
of two reference frequencies, but weighing factors are not the same:

  Fmain = k1main * REF1  +  k2main * REF2
  Fsub  = k1sub  * REF1  +  k2sub  * REF2


  REF1 = TCXO frequency
  REF2 = codec clock frequency

  k1main, k2main = main RX tuning factor  (k2main is constant for a given mode)
  k1sub,  k2sub  = sub  RX tuning factor  (k2sub * REF2  is tuned within 2.5 
kHz range)

Now look at condition for Fmain = Fsub:

  k1main * REF1  +  k2main * REF2  =  k1sub  * REF1  +  k2sub  * REF2


  (k1main - k1sub) * REF1  +  (k2main - k2sub) * REF2  =  0

With unlocked REF1 and REF2, as they are,
Fmain can be equal to Fsub if and only if:

  (k1main = k1sub)   and   (k2main = k2sub)

which happens only at a single point per 2.5 kHz tuning range.

At all other points, i.e. most of the time, k2main is different from k2sub,
preventing Fsub to be maintanied equal to Fmain.


Sinisa  YT1NT, VE3EA

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