[time-nuts] 10 MHz -> 16 MHz

Dave B g8kbvdave at googlemail.com
Mon Oct 1 11:30:59 EDT 2018


Moot point with free running clock oscillators in the digitising sound
cards often used.  Some of the all in one cards with fast A/D's and
FPGA's etc can take an external frequency reference.

Some "adjustment" of the data can be done in software, to calibrate the
frequency domain.  Smoke and mirrors!

But yes, good point.

Dave B.

PS: Thanks to whoever mentioned the ICS525 or 527 IC's.  Oddly, I'd not
come across that family of chips before.  I'm currently messing with an
old-school MC145151 PLL chip, to lock a 20.48MHz VCXO to 10MHz.  I
"abuse" the IC by swapping the reference and VCXO inputs to get the
needed division ratios (for an 80kHz phase comparison frequency.)

That and referencing the tuning diode from the +supply so the loop
tuning is the right way around seems to work scarily well.

The ICS525 would be a better bet perhaps, if I had to manufacture dozens
of the things.  However, making PCB's is an issue for me (no creation
facilities nor experience with the needed layout software) so "dead bug"
construction is the way at the moment!   Fun times...

>><<


------------------------------------------------------------------------
On 30/09/18 17:00, time-nuts-request at lists.febo.com wrote:
> From: Pete Lancashire <pete at petelancashire.com>
>
>
> It surprises me how the SDR designers in 90% of the cases don't even allow
> for an external clock. It's like accuracy never came into thought.

-- 
Created on and sent from a Unix like PC running and using free and open source software.
::



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