Our great sponsors
-
InfluxDB
Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
This is a great project! I was expecting a run-of-the-mill GPSDO, but this is way better.
I've been looking for more time sources to add to my own GPS clock: https://github.com/jrockway/beaglebone-gps-clock (which is one of those boring ones that everyone has).
I have been thinking about buying a rubidium oscillator from eBay for fun, but basically anticipated the problem the author had -- they have been mistreated for years before finally landing on eBay, and aren't any good. GPS is my only frequency reference, so I wouldn't really be able to fix it; I'm at the mercy of my very obstructed view of the sky.
I'd like to be able to measure how badly out of sync I get when I fall down from 16 satellites to 4 satellite throughout the day. I can sort of intuit that from the data I get right now (I send "chronyc sourcestats" to influxdb every 30 seconds, and you can see that when the GPS signal gets bad, the frequency error in my system clock also gets bad.), but I'd like to measure it conclusively. Will probably spend a bunch of money on the problem and become even more unsure which way is up ;)
The link to the "time to digital converter": https://www.ti.com/lit/ds/symlink/tdc7200.pdf is very interesting, and I totally forgot that I should be measuring AC powerline cycles to see how they're doing relative to GPS.
(In the past, I also incorporated a WWVB receiver, but get such a terrible signal in New York that I didn't get any usable data out of it. I then dropped the ceramic antenna and that was the end of that project. I have since realized that I can buy a phase-modulation receiver inside of a clock, throw away the clock, and try that, however. Ordering one right now, actually! Thanks HN!)