Its estimated phase noise floor is around -171 dBc/Hz with +13dBm output (and input) in the noninverting 2x configuration with a 50 ohm load and a 50 ohm resistor in series with its output. Thats about 3dBc/Hz less noisy than the measured 10MHz phase noise floor of a OPA653 in the same configuration with the same input and output signal levels.

It sends a supplemental timing packet that contains an estimate of the quantization error in its pulse output. But the manual isn't clear on whether that applies to the next pulse or to the previous one.

One that has not been mentioned is to > check on the validity of your long term GPS time estimate Small errors > that accumulate can be a really nasty thing … > > If you live in the mainland US, there aren't a whole lot of alternatives > to WWVB. Propagation is a reality that no amount of wishing will > eliminate. HF isn't going to do you much good.

One candidate might be this: multiply the signal by an estimate of its phase one minute ago. The frames are very similar minute-to-minute, as can be seen above. The exceptions are the parity word, changes in the metadata, and rollovers in the time word involving large numbers of bits.

The E-9 is an estimate. I'm looking for a good way to measure it with simple tools. Plans: I will add features and sophistication one step at a time and I will try to document the process. Even as I add more my goal is still (1) an understandable design that anyone can build with no special tools or equipment and (2) cost.

The BTO jumps between different types of channels, so only R-channel is being used for estimates. This positioning problem isn't very complex, but is a good exercise as it is similar to the pseudo-range measurements and positioning from GPS. The doppler and time observations with some basic geometry gives most of it out.

In this case, the phase detector gives you a very good estimate of the delta between input and output in real time. The error trapping / shifting / multi this and that simply isn’t needed in this case. The solution is much easier than the GPSDO. Let the OCXO warm up for a day or two. Yes it could be a week. Adjust it with a pot to be close to frequency.

That is a questionable assumption at 100,000 seconds, but you need at least 1,000,000 seconds of data to make even a low accuracy estimate there. If the objective is simply looking at the GPS, a 53132 counter will probably do a fine job. Run the 1 pps out of the GPS and a 1 pps out of the Rb.

The phase data is averaged over may days to make a precision estimate. This works ok for a frequency based (think GPSDO) type system). For autonomous timing it’s not a practical solution.

Even if an L1/L2 receiver gives you better ionospheric estimates, the orbit uncertainties still need postprocessing to be corrected. The only other thing I can think of is using multiple Rb's as reference, measure their temperature, air pressure and drift against GPS.