[time-nuts] 10 MHz -> 16 MHz

Alex Pummer alex at pcscons.com
Sun Sep 30 13:46:08 EDT 2018


and what wold happen if you divide the 10MHz by 10 -- with any simple 
counter chip -- and injection lock a 16MHz crystal oscillator with that 
1MHz, since the jitter is not critical .... of course it does not hurt 
if you make the 1MHz pulses narrow, you could use the micro-controller's 
own oscillator circuit, plus that counter [freq divider chip ] it is 
simple and cheap enough?

73

KJ6UHN

Alex


On 9/30/2018 7:54 AM, jimlux wrote:
> On 9/29/18 8:57 PM, Tom Van Baak wrote:
>> What's a clever, simple, reliable (pick 2 of 3) way to get 16 MHz out 
>> of 10 MHz? Low phase noise isn't a big requirement and jitter doesn't 
>> need to be sub-nanosecond. The main requirement is perfect cycle 
>> count accuracy. This is for driving a 16 MHz microcontroller from a 
>> 10 MHz Rb/Cs/GPSDO. 10 MHz input is likely sine; 16 MHz output is 3v3 
>> or 5v CMOS.
>>
>> Thanks,
>> /tvb
>>
>>
>
> cycle counts over what interval?  5 and 8 cycles respectively? or 
> over, say,  1 second?
>
> Multiply by 8 divide by 5 seems a bit tricky (although any number of 
> off the shelf DDS will do it at fairly high power dissipation)
>
> You might be able to injection lock an 80MHz oscillator by coupling 
> the 10 MHz in on the Vcc or output.
>
> Then a divide by 5 down to 16.
>
> If the requirement is over 1 second, then you can play a game with 
> counting the first half of the second, and adjusting in the second by 
> dropping/adding cycles to make it come out right. THat sounds pretty 
> icky.
>
>
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