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Starlink lacks the high precision atomic clocks on board of the satellites, that is also why Starlink needs a GPS fix to bootstrap itself.

by nomel10 hours ago|

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Maybe the starlink clocks could continuously calibrate from gps? Clock drift is usually a slow thing (like thermals). Their inter-satellite data links have all sorts of relative clocking info.

by numpad04 hours ago|

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IIUC, GPS picks one satellite and 3 more to establish time differences between the first one and the other 3. There's only one point in universe where the set of differences would match what was observed, given the broadcast orbital data of satellites, and that gives the location of the receiver. It's like you are provided radii and center coordinates of 3 circles on a paper that intersect at 1 point and you are to math that point.

So GPS-like systems need precise orbital data and coherent clock from each satellites, or otherwise the receiver cannot figure out those radii.

Presumably you can have each sats reflect a clock from the same master ground station but that's not how GPS is implemented currently.

by nomel1 hours ago|

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Coherency is a state. My question is if that state can be achieved by just tuning the individual clocks/locations based on GPS as a master. And, there's other tricks, with all the inter-satellite communication [1].

And, there's a contextual difference here between civilian GPS and military GPS. Much of the precision in the existing GPS satellites is to support the military use of GPS, with intentionally error injected into the civilian side.

And, by the nature of the hostile environment the military operates, military craft don't have as strong of a reliance on something that's ephemeral, like a GPS signal on a battlefield.

[1] https://arxiv.org/pdf/2501.05302

by skew-aberration34 minutes ago|

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What you describe is very normal in telecom and has been for a long time. 4G, 5G, etc are all totally dependent on every device syncing to the one higher up in the chain. These days typically a digital control loop is used to tune a high frequency voltage-controlled oscillator which feeds a counter. An event (like GPS PPS, or an ethernet frame arriving on the cable) is extracted from the signal and the counter generates a timestamp. The chips to do this are incredibly cheap and the performance is hard to comprehend.

https://www.ti.com/product-category/clocks-timing/clock-netw...

by himata41137 hours ago|

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We have starlink I am sure we can figure it out. Like... launch a better GPS system with one rocket?

by numpad04 hours ago|

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doesn't take sat swarms. what you need are some cash and bunch of educated and motivated smart people. that can be tricky sometimes