Problems with connection to remote camera

[mhalford]

Hello. I wasn't sure of the correct place in the forum to post this, but I work at a university and we are trying to control telescopes and cameras on a rooftop terrace from a classroom in the building below. We would like to do this using USB to Cat6 extenders, which we have been testing. This works well for mount and electronic focuser, but not for the cameras, which we are controlling using SharpCap: ZWO ASI183MM Pro and ZWO ASI178MC. We are struggling with the delay caused by the extender, which can be 4-5 seconds when images are taken at full resolution. It appears that frames are sometimes dropped mid-exposure and we're not sure why this is occurring. We also don't know why the delay is so long, since a USB2 connection should be faster than that. One person on our team suggested that it may be a USB handshake issue between SharpCap and the cameras. The issue is not unique to SharpCap and happens with the camera manufacturer's capture software as well, but we were hoping the issue could be addressed from the software side. Does anyone have any suggestions for how to address this or at least figure out what is going wrong? Thank you.

[admin]

Hi,

to be honest, I think the most reliable way to deal with a problem like this is to put a small form factor PC at the side of the telescope to control the camera and then to control that PC via the network over a Remote Desktop connection. Depending on what sort of imaging you intend to do, something like an Intel i5 or i7 NUC would probably be suitable.

I suspect the very low frame rates may be related to the handshake time being greatly increased between the two ends of the extended USB connection – every time another packet of image data needs to be transferred you have to wait for the round-trip time. Why it would also become unreliable is unclear, but unfortunately these means of extending USB range have always been a bit hit and miss – some people get good results and others run into issues. It may depend on the exact brand and model of USB/ethernet extension cables that you use - perhaps some other forum members have had good experience with these and would be able to share their tips.

Unfortunately this isn't something I can do anything about in SharpCap - the problems are occurring at a lower level inside the camer SDK and driver.

One thing to try would be to turn down the 'Turbo USB' setting to minimum to see if that helps with stability.

Cheers, Robin

[mhalford]

Thank you for the quick response - Intel NUCs at the telescope side is actually my preferred solution (and is comparable in price to the USB extenders) but I think that university IT is concerned about that setup from an information security standpoint, plus there would be additional time involved for the teaching assistants to set up the NUCs for each lab, since they are not weatherproof and cannot be left outside. I will pass that information along, though, and perhaps convince the others that it is the best solution.