SharpCap Timestamp accuracy

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SteveInNZ
Posts: 28
Joined: Tue Feb 14, 2017 6:56 pm

Re: SharpCap Timestamp accuracy

Post by SteveInNZ » Mon Dec 03, 2018 9:17 pm

Would AstroFlashTimer (https://sites.google.com/site/astroflashtimer/home) be of any use to you ? It's intended for occultations and has been tested against the IOTA VTI.

Steve.

Furgus
Posts: 16
Joined: Fri Mar 16, 2018 9:27 am

Re: SharpCap Timestamp accuracy

Post by Furgus » Sat Dec 08, 2018 5:22 pm

Thanks Dave,

Yes, I've thought about how things might run more reliably....I do indeed turn off wifi and bluetooth before every session.
I also change the priority (Task Manager, Details) in W10 to 'RealTime' for SharpCap (it defaults back to standard after a re-boot).
W10 generally manages time better than W7 I am told.
The NTP programmes seem to be RealTime priority anyway. (NTP from local GPS server that is, not internet!)
Thats a good point about the antivirus.

Having said that though.....there really is no problem with whats happening ie the stamping seems correct nearly all of the time. The mystery is why that should be so, as Robin has checked that the timestamp is allocated after the exposure is complete, not before! So there should be a one frame error time....which there is not! (see attachment).
I'd be happier knowing why this is working...but don't want it to change!

Furgus
Posts: 16
Joined: Fri Mar 16, 2018 9:27 am

Re: SharpCap Timestamp accuracy

Post by Furgus » Sat Dec 08, 2018 5:24 pm

Thanks Steve,
I'll have a look at Astro Flash timer.

Furgus
Posts: 16
Joined: Fri Mar 16, 2018 9:27 am

Re: SharpCap Timestamp accuracy

Post by Furgus » Mon Dec 10, 2018 11:12 am

A small clue, possibly, as to whats happening:
I find that when using a USB 2 cable, both ASI224 and ASI174 cameras produce frames that have a 'late' timecode, (very roughly 1 frame duration late).
When using USB 3 (which I always do).....the timestamps appear 'correct' nearly always (ie the timestamps match the 1PPS LED, within the limits of frame duration).
I can confirm that at least for long exposures (several seconds), that frames are given the timestamp value corresponding to the end of each exposure.
Its therefore very odd it appears correct at normal 'video' type frame rates!

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