Based on the noise estimate you get, and the calculations above, come up with a schedule. No need to get obsessive about it. All you are looking for is: read every day / every three days / once a week sort of spacing. Start logging your phase offset at what ever spacing makes sense. Take at least ten readings.

error 1 us, TAI offset 0 ntp_adjtime() returns code 0 (OK) modes 0x0 (), offset 72.469 us, frequency 143.112 ppm, interval 256 s, maximum error 6000 us, estimated error 1 us, status 0x2107 (PLL,PPSFREQ,PPSTIME,PPSSIGNAL,NANO), time constant 4, precision 0.001 us, tolerance 496 ppm, pps frequency 143.112 ppm, stability 0.234 ppm, jitter 0.663 us,

Hi Bruce You are absolute right that it is wise to put some time in the estimation of such effects as asynchronous Clocks. An iteration between thinking and building seems always to be necessary but we all have different capabilities for that. For the Arduino I came to an end with the interrupts as I am not good at uP´s.

But because of the conservative estimate it might 150 times to small to measure. So randomly delayed reads of the ADC will not matter. That said I'm sure we can do 100X better then the 63 uS estimate. On the other side, charging the cap. Let's say I mis-measured a wire and it is 1cm longer then I though.

Turns out that the details of how a particular vendor implements the frequency estimation and filtering can be devastating in getting comparable frequency measures, and thus loosing the observation precision needed to follow the aftermath properly.

The location estimate in NEMA is also heavily filtered and referenced to its utc time estimate (PPS). Conceivably could be filtered to a bandwidth of Fs/2, 500 milliHz.

Remember that there is typically an "approximate" estimate of the range, so if you look at the phase difference of the ranging tone, you can figure out where you are within the "cycle".

Do you know how they estimate the temperature? I checked almost every IC on the STAR4 PCB and was unable to find a temperature sensor. Is it possible to estimate the oven temperature from the current drawn? (for sure it is, but most likely it will be strongly dependent on the particular OCXO used, I think).

I don’t know of >>> any receiver that directly estimates Tropo delay. >> There is means to infer Tropo-delay with single receivers, but it is not >> very accurate that I've seen. However, the usual way is to use nearby >> receivers as reference.

In 2014, researchers published a study in the journal Supercomputing Frontiers and Innovations estimating the storage capacity of the Internet at 1e24 bytes, or 1 million exabytes. When I started working for Memorex, an IBM 2314 disk pack could store 29.2 million bytes.