QHY 174 GPS time stamps

[wunni]

Hello,

The QHY 174 GPS is supposed to be the solution for any timing problem. But you have to know what time SharpCap outputs as a time stamp - shutter open or shutter closed, or something in between?
I didn't find anything in the SharpCap manual, the camera outputs what you want (or what is coded).
Trying to find out for myself with a 1PPS LED did not provide a conclusive answer.

Does anyone know for sure?

Speaking of the log file: How do you get SharpCap to additionally write every single timestamp (means shutter open AND shutter closed time) into the log file?

Thanks in advance!

Best regards,
-wunni

[admin]

Hi,

if you capture to FITS then every frame will have two time headers (for the start and end of the frame). The header comments explain which is which.

You can log all GPS info to file by turning on the option at the bottom of the first page of the settings. This creates a separate log file that is saved in the root capture folder.

Hope this helps,

Robin

[wunni]

Hi Robin,

thank you for your reply. FITS would be one way to find out what time (start, middle or end of frame) is written in a timestamp. I'm gonna do some experiments.
(For occultation work I perfer ser files.)

The GPS log is available from SharpCap 3.1 and higher. Unfortunately, it doesn't work properly with my camera, so I have to use v3.0.
(I think it is quite a joke if there are tools to get the microsecond when you don't even know what time the timestamp represents.)

Best regards,
-wunni

[admin]

Hi,

I'm a bit surprised that you aren't getting the GPS camera to work with the latest version of SharpCap – I use my GPS camera with a very latest SharpCap 3.2, and I know that the guys who do the occultation measurement for NASA also use the latest SharpCap with their GPS cameras. One thing that has caused other people problems is that newer versions of SharpCap may require you to install an updated Windows driver for your qhy camera.

If you choose to write to SER file then the frame timestamps will be the start of the frame according to the GPS information. Note that if the GPS is not locked or loses sync then the system clock is used for timestamps instead and in those cases the frame timestamp will actually be when the frame is handed over to SharpCap, which will be after the frame has ended and been transferred to the computer from the camera.

Cheers, Robin

[wunni]

Hello Robin,

thank you for your answer! It helps a lot.

Regarding ShapCap 3.2: I use the most recent system driver (as far I know) (on Windows 8.1).
I wonder: Since there are people who use the latest SharpCap with the 174 GPS, it must work, but what am I doing wrong?
On the CD supplied with the camera there is a program that probably patches SharpCap 3.0. Do I have to use it with SharpCap 3.2 too, do I need it at all or do I need another patch?
By the way: SC3.2 worked quite fine until I agreed to activate the Pro test version. Then it stopped reading the GPS and ran as if with the handbrake fully pulled. It stayed like that, even after a new installation; apparently I didn't reset everything.

Cheers,
-wunni

[admin]

Hi,

the program that comes on the CD should not be used any more for SharpCap 3.2 - it tries to update the version of the QHY SDK in SharpCap, but since the CD is now old it would actually be putting in an older version.

It sounds like maybe you need to adjust the 'USB Traffic' control if your camera is running very slowly (https://docs.sharpcap.co.uk/3.2/#QHY%20 ... 20Controls).

Robin

[wunni]

Hi Robin,

Mixing v3.0 and v3.2 certainly caused problems. Setting of USB-traffic is not the reason; I set it to 0 to get max. fps for testing.
Unfortunately, I will not be able to make further attempts until mid-January.

Best regards,
-wunni