Fragmented Frames

Sequence Generator Sequencing
1

Hi,

Intermittently, I would encounter fragmented frames when acquiring subs at 2-3 mins per frame or flats that has a couple of secs in a sequence. I’m using the latest version of SGP Pro v4 64-bit and latest version of All-in-one QHY driver package for my QHY294C cooled camera. Statistically, the fragmented frames are usually less that 10% of the total images acquired. I have observed no high CPU contention during the sequence, other than having PHD2 and ZWO guide camera at the same time for guiding.

In the past, I have tried connecting direct USB 3 cable from camera to my laptop USB3 port, and now moved on to Pegasus Power Box, but the issue persisted before the power box, even with new USB 3 cables.

I have tried to uncheck the “Use High Speed Download (if available)” option even though I am aware that it does not apply to sequence, as expected, the issue persisted.

There is a USB Traffic setting from the QHY ASCOM driver that defaults to 0 (fastest download) but according to QHY Facebook post, for single frame, the driver will default to 0 regardless of any input attempted to slow down the transfer rate.

Any suggestions would be greatly appreciated.

C2.PNG
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2

If you upload one of these fragmented files to a file hoster and post the link here I can take a look whether they can be repaired.

Bernd

3

Hi,

Can try to download from this link.

Thanks.

4

@chonghaic

This is a commonly reported issue. This fragmentation is said to be caused by errors on the USB interface. Sometimes it is the USB cable itself and sometimes it is the hub. It is also suggested to set the USB interface speed (in the ASCOM interface) to 30. Since the QHY camera powers its electronics from the USB interface, a robust, powered USB3 hub is a must. The 12v power to the camera is used only by the TEC.

Charlie

5

I am sorry, but I cannot rescue the data. One observation catched my eye: QHY specifies an effective pixel area for the QHY294C of w = 4164 px and h = 2796 px whereas the FITS file has w = 4212 px and h = 2850 px. Is this also the case in not fragmented files?

Bernd

6

Thanks Bernd for the effort.

The good subs were also 4212 x 2850 px.

7

@chasmiller46

Thanks Charlie for emphasizing the need of a robust USB3 hub. I did not mention earlier that I had invested a few high quality USB3 cables and external powered USB3 Hubs, with the latest Pegasus Advanced Power Box v2 and expensive Pegasus power adapter that guarantees stable voltage and stable current (10A).

I will try setting the QHY ASCOM USB Traffic to 30 and see if it helps. If that doesn’t work, then I will try to get another laptop with USB-C interface bridging to the USB 3.1 hub.

Chong Hai

8

You may also be downloading the over scan area of the chip. This can be disabled in the QHY ASCOM setup dialog.

Charlie

9

Thanks Charlie, for the overscan suggestion.

I have tried setting the USBTraffic to 30 and removed the overscan but the issue still persist.

Guess will have to get another laptop to try it out.

QHY
QHY1217×892 158 KB

Chong Hai