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by tejtm 880 days ago
can we not now use fiberoptic cables to provide a common timestamp signal well above the shannon limit of the emmission lines that would need to be reassembled
2 comments

Another interesting possibility is to use GPS for a clock. [1] Apparently 1 microsecond accuracy. Maybe useful if you want to make the distance really far. Someone has an article [2] Would be cool if you could pool the resources of multiple amateur rigs over a great distance in ad hoc antenna arrays.

[1] https://digitaldisplay.com/network-clock/master-clock/gps-vs....

[2]https://destevez.net/2022/03/timing-sdr-recordings-with-gps/

Yeah GPS is a good tool to sychronize over very long distances. Locally locked clocks might still be better for an array not far away from each other if done properly. GPS might be easier to implement for amateurs though.
Imagine every amateur radio astronomer pointing their dishes at the same thing. If they all upload their data with accurate enough GPS position & timing, it could probably be used.
We just need a standard file format that incorporates the thing being observed and some GPS time sync info (or other time sync source). Anything else? I'm game.
I think this would be amazing to ttack movements but the combined images would be extremely noisy wouldn't it?
Short answer is: no. The long answer is: Speed of light on glass is not so different than electromagnetic signal speed in copper, approximately 0.66C. Considering clock sources output electrical signals, using a coax cable instead of fibre optic has several advantages: simpler signal chain means lower delay, and avoiding highly noisy optical-electrical conversion means less jitter.

Fun fact: RF signals in air travel faster than light in glass fibre (0.8C instead of 0.66C).

A belated Thank You! for your excelent reply.