this post was submitted on 06 Oct 2024
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Fucking Time Propagation (lemm.ee)
submitted 2 months ago* (last edited 2 months ago) by [email protected] to c/[email protected]
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Just bought the GWM 5610U-1C. It was a tough decision choosing between the DW5600 and this, ended up choosing this because the atomic time keeping is cool.

However, I'm a tad annoyed that the time doesn't perfectly match with time.gov and time.is since the atomic sync doesn't account for time propagation, so there's like a fraction of a second delay that's noticeable. Other than that, the watch is fantastic and has most features I would want. (I wish it had barometer and altimeter stuff, maybe even compass, and dive rated so I can press buttons underwater)

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[–] [email protected] 3 points 2 months ago (1 children)

Wow this is a wonderful comment. Thank you so much. This is probably the best it's gonna get unless I get a bluetooth smartwatch type thing, which I'm not going to do.

However, could you explain why from my napkin calculations earlier today, where I used the the speed of radio waves, which from what I learned, is close to the speed of light, I got around .0045 seconds from colorado to the area of los Angeles. Yet from comparing my watch up against another screen with time.gov and time.is, I can visibly tell that it's much greater than that, something like maybe 1/4 of a second off. Is it because of interference? What could cause this big jump in numbers?

[–] Bach37strad 2 points 2 months ago* (last edited 2 months ago) (1 children)

Delays in network infrastructure. While most signals going between large nodes/hubs will be fiber optic, there's quite a few old school copper connections between you and the time server that will slow things down. My ping to my closest node, with all my fiber and cat5e connections is still 20ms.

You're probably better off using a cellphone time than a desktop computer to a website, since the cell network accounts for the difference in time dilation between us and the satellites (Einsteinien relativity amitright?) supposedly well enough for network infrastructure to work.

You're also getting to "is the processor in the watch fast enough" territory. That's a bit beyond me though.

[–] [email protected] 1 points 2 months ago

The watch would be radio controlled so the delay wouldn't be determined by the network infrastructure but by the interference in the air. The watch's stopwatch can do split second 1/100 so surely it is precise enough. I'm leaning towards this being an issue of interference.