[time-nuts] Designing an embedded precision GPS time

Bob Martin aphid1 at comcast.net
Wed Nov 1 09:35:23 EDT 2017

One can minimize temperature change which affects things like 
regulated voltages, CMOS transition points for those converting
sine to TTL with gates, etc. in addition to the oscillators.

The November issue of Nuts and Volts Magazine has an article on an
Arduino based PID controller which might interest someone who wants 
to experiment with reducing temperature effects by controlling 

Bob M

On 10/31/2017 8:42 PM, jimlux wrote:
> On 10/31/17 1:47 PM, Bob kb8tq wrote:
>> HI
>> TCXO is a very loosely defined term. A part that does +/- 5 ppm 
>> -40 to +85C
>> is a TCXO. A part that does +/- 5x10^-9 over 0 to 50C may also be 
>> a TCXO.
>> Dividing the total deviation of either one by the temperature 
>> range to come
>> up with a “delta frequency per degree” number would be a mistake. You
>> would get a number that is much better than the real part exhibits.
>> Working all this back into a holdover spec in an unknown temperature
>> environment is not at all easy.
> Very much so - most of the TCXO curves I've seen tend to be "much" 
> better than the spec over the central part of the frequency range 
> (which makes sense, the underlying crystal is a cubic with temp, 
> most likely)
> Retrace and hysteresis might be your dominant uncertainty.
> I've attached a typical TCXO data plot for your viewing pleasure..
> (that's an expensive oscillator, because it's for space, but I don't 
> think space or not changes the underlying performance)
>> Bob
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