As has been pointed out in these discussions, > Motorola reports an estimate of the error on the NEXT 1PPS tick. Slides > 21 and 22 show some of the pathological example we have seen on typical > receivers.

However it can estimate the resultant timing error with a resolution of 1ns (for the M12 GPS timing receiver and its derivatives). The resultant sawtooth error can either be corrected in hardware as in the CNSClockII or it can be corrected in software (if the PPS transition is time stamped with sufficient precision).

I specifically cautioned Ulrich from making Allan Deviation performance estimate from the frequency performence for this reason. The smoothing will make such rule-of-thumb comparisions much harder.

A crude way of estimating the propagation delay mismatch tempco for CMOS ICs is to assume that the propagation delay mismatch has the same tempco as the propagation delay itself or about +0.4%/C. e.g. if the propagation delay is say 10ns and the mismatch is 10% (1ns) then the delay mismatch tempco will be in the region of 4ps/C.

Even with a perfectly known aging, only a few oscillators would bother to estimate and correct it. This can never be perfectly done anyway, and there is only so many things you can bring into the model while keeping it economical. There is fairly good clues around. If all was included and handled, it would reduce the effects.

Bob -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of EWKehren@aol.com Sent: Thursday, January 12, 2012 10:43 AM To: time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A Mechanical Question Bringing out the C field in my estimation does not effect long or short term.

. > > A sine modulation of frequency and the way we can estimate > it's impact > on future time is quite different from that of inherent > noise sources. > Also, it doesn't scale to the white frequency noise. > > Similarly, other systematic effects should be separated out > of the data > before noise analysis. > > > Does this make sense?

Basic TDR/TDT doesn't need any additional software to get an estimate of the reflected impedance. But the iConnect software (which was developed by a small company which Tektronix purchased many years ago) allows much higher accuracy and removes most of the ambiguity of multiple reflections.

Enrico presented an approach to estimate the removed noise and simply add it back. Mike Driscoll discussed the potential of doing a different approach with mixers for higher amplitude level.

A copy of his paper: "Estimation of GPS Ionospheric Delay Using L1 Code and Carrier Phase Observables" https://apps.dtic.mil/sti/pdfs/ADA497270.pdf You'll see the Motorola Oncore VP mentioned in several places. He used a 5061B and a simple M/N PLL to give 3590 / 188 MHz = 19.0957 MHz. I don't recall any other papers describing a similar experiment.