You're overestimating how precise the clocks in normal electronic devices are. A typical PC clock is +/-100ppm. After 1 hour that's 0.36s, which is roughly 100km in distance. A good electronic clock is a tenth that. An OCXO is in the 1ppm range, but that's still a kilometre per hour.
There's a reason GPS satellites are used as reference clock for PPS, PTP and NTP. A naval vessel you could carry a Rubidium clock on, I guess. But on ground vehicles or mobile receivers... nope.
[ed.: OCXOs aren't that large, 1cm^3 box ballpark, too large* for a smartphone or laptop but not a problem on larger quadcopters, cars or military radio equipment. And 1ppm is long term drift, you can try compensating a bit beyond that, so - I guess it's a question of spending the money and energy** on OCXOs.
* thick specifically, can't easily be made thin AFAIK
** the first O there is Oven - roughly 0.5W continuous draw.]
Yes, albeit 100ppm is bad/cheap crystals. 50-30ppm is normal.
The difference with a quartz watch is that it's factory calibrated with the load capacitance on the crystal, and that it's a 32768Hz tuning fork. For a variety of reasons, generating higher frequency clocks off 32768Hz is... "annoying" (huge PLL ratio, very slow feedback loop step), and typical crystals in the 10-100MHz range are just less precise and thermally stable. (Not sure why, I'm not an oscillator manufacturer...)
(NB: you can of course correct for initial deviation in software. The actual problem is stability over temperature.)
> benefits from being kept at constant-ish body temperature
Some people take off their watches every day before going to sleep.
These high-end quartz oscillators are probably too expensive to use in commodity computers. Still, the cost shouldn’t look too bad when compared to a price or an airplane, marine vessel, or most military equipment.
We're in agreement; 1ppm is 31.5s/yr so this lines up with OCXO performance / keeping the crystal at constant temperature. It's still 1km zone of spoofability per hour without resync.
I'm unaware of any technology between OCXOs and Rb standards. The latter have gotten smaller but not tiny and also need quite a bit of ongoing maintenance and calibration.
There's a reason GPS satellites are used as reference clock for PPS, PTP and NTP. A naval vessel you could carry a Rubidium clock on, I guess. But on ground vehicles or mobile receivers... nope.
[ed.: OCXOs aren't that large, 1cm^3 box ballpark, too large* for a smartphone or laptop but not a problem on larger quadcopters, cars or military radio equipment. And 1ppm is long term drift, you can try compensating a bit beyond that, so - I guess it's a question of spending the money and energy** on OCXOs.
* thick specifically, can't easily be made thin AFAIK
** the first O there is Oven - roughly 0.5W continuous draw.]