[time-nuts] Re: ISS time standards and updates

[Lux, Jim]

On 5/26/21 4:45 PM, Ronald Held wrote:
> What is the main reference time on the ISS?  Is it a primary frequency
> standard? How is it updated?
>   

Others may weigh in with better info, but as of a few years ago, there 
wasn't anything like a "house 10 MHz" - most things were timed off the 
MIL-STD-1553B bus if they needed timing. There is Ethernet, but I don't 
know if there's an NTP server, or whether they've implemented anything 
like PTP.  For the most part, if you need good timing for your 
experiment, you fly your own reference (a GPSDO or a Rb or something).

Typically, you don't even know where you are in 3D space that accurately 
- there's a Broadcast Ancillary Data (BAD) stream with XYZ and rates, 
but it's generated as a predict by Goddard's Flight Dynamics Facility.  
For that matter, the entire structure (which is as large as a football 
stadium) flexes quite a bit (meters), so if you're looking for meter or 
nanosecond accuracy, you would need to ask "relative to where".

https://www.nasa.gov/mission_pages/station/research/quick-start-guide


https://www.nasa.gov/pdf/190373main_TP-2007-214768.pdf

http://large.stanford.edu/courses/2014/ph240/clark1/docs/np-2010-09-682-hq.pdf