[time-nuts] Trimble Tbolt temperature

[Bob kb8tq]

Hi

Again, since it’s a Kalman, even the people who designed it were a bit unclear
about just what was going on inside. Was 0.1C data useful vs 1C ?…. nobody
really knew. Based on many measurements of the TC of the DAC / Ref on the
TBolt, it could indeed use some “help” when in holdover. 

One would *guess* that when the lower resolution chips came along the units 
still passed the 100% holdover testing and they moved on. 

Bob

> On Dec 9, 2019, at 12:17 AM, Charles Steinmetz <csteinmetz at yandex.com> wrote:
> 
> Didier and Bob both suggested that perhaps the Tbolt's Kalman filter is better served by the "other corner of the board" temperature data supplied by the existing DS1620, and was designed to operate that way.
> 
> If this were true, we would expect Tbolts with newer DS1620 chips (chunky 1C temp data) or defective DS1620s (e.g., constant minimum temperature reporting, such as -55C) to perform *VERY* differently in holdover than Tbolts with properly operating, mC resolution DS1620s. But all indications are that there are no such differences (and there are reams and reams of historical data on this).
> 
> So, I remain convinced that the Tbolt's Kalman filter operates as I described in my last message (12/4).
> 
> Best regards,
> 
> Charles
> 
> 
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