"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
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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