QHY174 GPS calibration: Cause of Start/End Pos scale change

[Kai Getrost]

Another question on QHY174 GPS calibration: the SharpCap interface for setting Start and End Pos has changed over time. As I recall, in 3.2.6062, Start Pos was settable 0-15K and defaulted 0, End Pos was settable 1-20K, defaulting to 1K. In 3.2.6226 or thereabouts, both changed to a range of 0 - ~1B, and defaulted to a dynamic auto-preset empirically computed from Binning, Exposure, and other factors. (And there were some intermediate interfaces as well, I recall.)

What precipitated this change? Was it any/all of the following:

1) The underlying QHY API for setting Start/End Pos changed at some point. Perhaps taking a different range of numbers? If not, what exactly changed?
2) SharpCap changed how it maps the GUI Start/End Pos values to QHY API Start/End Pos sent to the camera; i.e. maybe it used to multiply by e.g. 1000 to avoid large numbers in the GUI, but now sends the values as-is. Perhaps to allow more fine control over Start/End Pos in the GUI?

Or something else? Or perhaps both 1 and 2? Thanks.

-Kai

[admin]

Hi,

I think it was mostly option 1 - when I first had the GPS camera it seemed that the values in the initial smaller range would give good calibration – perhaps the SDK has changed or perhaps the fact that I was less experienced in the use the camera back then has a role to play. Coming back to the camera later to try to add more features I discovered that the small range was just not sufficient to get good calibration and had to change things around considerably.

Cheers, Robin

[Kai Getrost]

I think it was mostly option 1 - when I first had the GPS camera it seemed that the values in the initial smaller range would give good calibration ...

Thanks. And to clarify -- were/are the SharpCap GUI-set Start/End Pos numeric values ever manipulated (scaled, offset, etc.) before being sent to the QHY SDK, in any version of SharpCap? E.g. in 3.2.6062 the GUI range was like 0-20K: were the GUI values scaled x1000 or something to more broadly cover the QHY SDK range? Or were they left as 0-20K when passed to QHY, and that just worked at the time? Thanks.

-Kai

[admin]

Hi,

no, they were never scaled up even when they had the smaller range. The values were just passed straight through to the SDK.

Cheers, Robin