QHY 174 GPS Calibration LED issue // USB Traffic weirdness

[SteveInNZ]

Robin,
We both have early release versions of this camera and I wondered if you ever managed to get good GPS data when imaging in 16 bit mode ?

Steve.

[admin]

Hi Steve

The early cameras need a firmware update on two different components inside the camera before the GPS will work in 16 bit mode. I have the parts needed to do the firmware update on my camera, but so far I haven't worked up either the courage or the time required to try it out!

Without the firmware update then the output in 16 bit mode is just junk I'm afraid.

Cheers, Robin

[SteveInNZ]

Thanks Robin. It's no longer that important to me. More of a loose end that would be nice to tidy up.
I might pursue it further when I run out of things to tidy up.

Steve.

[denisgre]

Hi there,

I've been struggling with my QHY 174M GPS for over a year now and have yet to have a successful imaging run with it.

The latest error is "BadCalibrationReduceEndPos" which appears in the status section. Any ideas what would be causing this or how to correct?

I'm generally seeing the GPS work intermittently for a few seconds at best before it freezes and a hard camera restart is needed.

My PC has 8GB of memory and an i7 processor running at 2.70 GHz / Windows 7 Pro. The USB ports are 2.0. If the problem is that "your computer is inadequate" then that is a valid response. I really want to be able to turn out for an occultation and be up and running quickly and reliably - so far no joy.

Thanks for any assistance.

Denis Grey
Toronto, Canada

[procyon12]

Hi Denis,

Yes, the QHY174GPS can be very difficult...

But in principle it should work also with your computer. However, the main problem there is the USB2 port. To fully utilize the potential of the QHY174GPS camera, USB3 is strongly required. For occultation work USB2 will be not sufficient.

But for testing, with a small ROI (640x480) and a low FPS (0.5), you should be able to get it working also with USB2. "BadCalibrationReduceEndPos" means that you do not have calibrated (right). How to do this you can find here: https://www.iota-es.de/qhy174gps_workshop.html, especially here (chapter 2.2): https://www.iota-es.de/qhy_workshop/part2_advanced.pdf . In your case you must reduce the values at the bottom of GPS controls until the LED goes ON.

To get it stable, your GPS antenna needs an unobstructed view to the sky.

I hope this can help.

Christian

[denisgre]

Hi Christian,

Thanks again for your help with this. I just wanted to report that I've upgraded my laptop to a faster machine with native USB 3 support. I've been able to get "Locked" and have it carry on for several hours at a time. After futzing around with this for 18 months this was very encouraging!

My last observation seems to be that when you switch the camera from "occultation mode" with short exposures to "picture mode" with longer exposures that the GPS gets confused and gives up. I think that can be lived with as having accurate time stamps on 5 or 30 second exposures is not really useful.

In any case I'm going to configure the recommended profiles to see if I can get some working instances for my next occultation event (which will likely be in 2022 now that my equipment is working

Best,

Denis Grey

[admin]

Hi Dennis,

Good to hear that you have a system that works now. I must admit that I don't usually test the GPS functionality with exposures longer than about a second – I wonder if it is an issue with the calibration being difficult at long exposures or something else in the camera that makes it unhappy at longer exposures. Has anybody here had any success with longer exposure images working with the GPS functionality?


One last thing to note is that unless you have the latest model camera with updated firmware, the GPS does not work in 16 bit mode, so if you are switching your camera to a higher bit depth for longer exposures that could be the cause of the problem.

Cheers, Robin

[procyon12]

Hi Denis and Robin,

Congratulations that it works now, Denis.

Regarding longer exposures I've made a test, only with 1 set of parameters and with the SC default calibration values, no fine tuning.

[QHY174M]
Output Format=FITS files (*.fits)
Binning=1x1
Capture Area=480x300
Colour Space=MONO16
Pan=744
Tilt=420
Force Still Mode=Off
Enable Live Broadcast=Off
USB Traffic=3
Offset=20
Amp Noise Reduction=Off
Frame Rate Limit=Maximum
Gain=480
Exposure=13000
Calibration End Pos Adjust=975006827
Calibration Start Pos Adjust=9661
GPS Calibration LED=On
GPS Freq Stabilization=On
GPS=On
Timestamp Frames=On
Contrast=0
Brightness=0
Gamma=1
Temperature=35
Target Temperature=0
Cooler Power=255(Auto)
Banding Threshold=35
Banding Suppression=0
Apply Flat=None
Subtract Dark=None
#Black Point
Display Black Point=0
#MidTone Point
Display MidTone Point=0,5
#White Point
Display White Point=1
Notes=
TimeStamp=2020-06-11T15:28:07.1576502Z
SharpCapVersion=3.2.6356.0

I increased the exposure from 10 to 13 sec, all went O.K. More than 13 sec were not possible because the Calibration End Position reached the maximum, see the screenshot. However, for occultation work there are no problems.

Christian

[admin]

Hi,

I can adjust this maximum up by about another factor of four and then we run out of adjustment in the Qhy SDK. I think that would get you to about 57 seconds maximum.

Thanks for checking out the cause.

Cheers, Robin

[procyon12]

I can adjust this maximum ...

Good idea, Robin.

Christian