[time-nuts] 10 MHz -> 16 MHz

Bob kb8tq kb8tq at n1k.org
Sun Sep 30 16:05:32 EDT 2018


If (as originally specified) noise and jitter are not a big deal - there are a lot 
of chips out there like the ICS570. They are designed to do weird ratio frequency
conversions so 10 to 12 or 10 to 16 are trivial for them. The Clockblock board was
one way to get it all put together. 


> On Sep 30, 2018, at 12:05 PM, Gerhard Hoffmann <dk4xp at arcor.de> wrote:
> Am 30.09.2018 um 16:49 schrieb Attila Kinali:
>> The simplest way I can think of is the following:
>> Use a 74LV8154 to divide the 10MHz down to 152.587890625Hz.
>> Use the capture timer unit of the uC to measure the phase of the
>> pulse. Use any kind of DAC (internal, external, PWM,...) to steer
>> the 16MHz VCO. Depending on how fast the timer unit runs, this
>> will give you something in the order of 10-200ns dead-band.
>> By choosing the right frequency for the timer unit, one can
>> get it to "dither" a bit and then use averaging.
>> For lower jitter, use one half of a Nutt interpolator
>> to get the timing difference between the 152Hz signal
>> and the 16MHz (ie similar to what the SRS FS740 does).
>> Use something akin Nick Sayer's time-to-amplitude converter
>> for the fine measurement.
>> Same works equally well for 12MHz.
> Wow. That's truly a Rube Goldberg design.
> There is a simpler way.  IDT ICS570. Digikey 800-1073-5-ND
> Solder time less than 10 minutes.
> I had the 3V3-Version in the parts drawers, officially it takes the 5V
> version to generate the 160 MHz, but the 3V3 version happened to work, too.
> The difference between 120 and 160 MHz is just a GND wire on pin 6 (vs. open)
> Divide by 10 is left as an exercise.
> regards,
> Gerhard
> (But then, some like to build and tune multiplier chains and mixers.)
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