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Re: Reference of timestamp

Posted: Tue Jun 06, 2023 9:20 pm
by mcamilleri
Sorry, no. I wrote that poorly.

I meant the qhy174gps. ZWO has no GPS cameras (though I am sure they could make them if they wanted to)

Re: Reference of timestamp

Posted: Wed Jun 07, 2023 12:23 pm
by saci
Hello Michael, ;)
for the SERs in SharpCap the timestamped time is equivalent to the end of the exposure whereas with tangra the measured time is in the middle of the exposure for example with an integration time of 0.120s I will subtract 0.06s from my SER to get the exact time what tangra does.
karim saci

Re: Reference of timestamp

Posted: Wed Jun 07, 2023 2:27 pm
by saci
One thing that would be nice is to add the microseconds to the timestamp in SharpCap..

Re: Reference of timestamp

Posted: Thu Jun 08, 2023 2:02 pm
by admin
Hi,

I'm not sure that adding microseconds to the timestamp in the frame image would be very helpful - from the discussion above we know that for non-GPS cameras the timestamp that SharpCap applies is quite a number of milliseconds after the frame ends, so I think there is no real data in the microsecond figures - it's all noise...

cheers,

Robin

Re: Reference of timestamp

Posted: Thu Jun 08, 2023 9:59 pm
by saci
Hi
<<I'm not sure that adding microseconds to the timestamp in the frame image would be very helpful>>
For my part it would be useful in 50X50 format at 2250im/s to film a flash-led /PPS of a gps or for those who need it .. ;) also it is used to set the time offset of the pc with an app. knowing precisely when the led changes state and thus determines the start of the second by this method.
GIF 23 12 22 gps PPS.gif
GIF 23 12 22 gps PPS.gif (29.26 KiB) Viewed 3594 times

Re: Reference of timestamp

Posted: Sat Jun 10, 2023 11:26 am
by celkins
Hi, I hope you don’t mind me chiming in, but I think you’re missing Robin’s point, here: you can have arbitrary precision in the time reported, but Windows doesn’t provide for accurate timestamps at such precision… Windows internal timekeeping isn’t accurate below milliseconds, regardless of the precision reported.

Re: Reference of timestamp

Posted: Sat Jun 10, 2023 12:40 pm
by saci
Thank you for your answer if I understand correctly .. even a camera equipped with a gps or a time box under a windows pc will have millisecond precision but not better.

Re: Reference of timestamp

Posted: Sat Jun 10, 2023 2:05 pm
by admin
Hi,

the QHY 174GPS is accurate to the microsecond once calibrated properly. There are a couple of other QHY GPS models, but they use progressive scan sensors (unlike the global scan 174IMX), so different rows of pixels are exposed at different times. There is also a Moravian camera with GPS and getting the data from it read by SharpCap is on my todo list...

cheers,

Robin

Re: Reference of timestamp

Posted: Sat Jun 10, 2023 2:18 pm
by procyon12
Hi,

Robin is right. I would add the SWISS DVTI camera https://dvticam.com/product.

An example frame of the QHY174GPS:
qhy174gps.jpg
qhy174gps.jpg (390 KiB) Viewed 3526 times
There is also a Moravian camera with GPS and getting the data from it read by SharpCap is on my todo list...
Interesting, Robin - do you have a link?

Christian Weber

Re: Reference of timestamp

Posted: Sat Jun 10, 2023 2:48 pm
by admin
Hi Christian,

there is this page talking about options for GPS modules : https://www.gxccd.com/art?id=715&cat=1&lang=409

There is a forums user who obviously has one, since he was the one who asked me to add support : viewtopic.php?p=36188&hilit=moravian#p36188

cheers,

Robin