[Elecraft] Re: K3 Beta Firmware Release -- MCU Revision 2.15

[wayne burdick]

On Jul 9, 2008, at 6:41 PM, Leigh L. Klotz, Jr. wrote:

> Is this to minimize a constant frequency shift between TX and RX....

It's to ensure *no* frequency shift between the two (just in -S mode), 
which minimizes T/R delays because we don't have to switch crystal 
filters.

AMTOR and related modes can also be used without engaging SYNC DATA, 
assuming a suitable value of CONFIG:PLL RLS is set up. I'll expand on 
this topic in an application note when I get a chance.

73,
Wayne
N6KR

> wayne burdick wrote:
>> MCU 2.15 / DSP 1.84, 7-8-08
>> ...
>> * SYNC DATA: Selecting sync data or “-S” now ensures that the
>>   same crystal filter will be used for both RX and TX -- either 2.7 
>> or 2.8 kHz.
>>   (Sync data mode, enabled by assigning PF1 or PF2 to CONFIG:SYNC DT, 
>> can be
>>   used to minimize the error rate of AMTOR, PACTOR, ARQ, and similar 
>> modes.)
>>   While -S is in effect, the receive crystal filter cannot be changed 
>> with
>>   XFIL, and SHIFT/LOCUT/HICUT are unavailable. WIDTH can still be 
>> changed,
>>   but it will affect only the DSP IF, not the crystal filter. The RX
>>   and TX first I.F.s will thus remain identical, a requirement for -S 
>> operation.
>>
>
>

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