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Fast exposure / fps capture over gigabit possible?

Posted: Mon Jan 13, 2020 8:56 pm
by markm75
Anyone have any experience on using sharpcap to capture usb 3.0 over gigabit with higher exposure planetary targets (IE: the bright moon for instance)?

Its my experience it really cant be done, as many frames get dropped over the course of say 500 or more frames even.

Curious if there might be a trick or way of buffering this to be possible however

Thanks in advance

Re: Fast exposure / fps capture over gigabit possible?

Posted: Tue Jan 14, 2020 1:58 am
by BlackWikkett
It's possible to use gigabit Ethernet with with a USB to Ethernet adapter but gigabit Ethernet has no where near the data transmission capacity to accomplish high speed imaging. Gigabit Ethernet maximum through put using TCP/IP without jumbo frames is about 120 MB/sec. The USB 3 through put is 640 MB/sec. Now most camera's will never push 640 MB/sec but you can easily reach close 200 MB/sec if you lower ROI on a typical camera. You could always limit the frame rate not to go past Ethernet's capacity but this is not reliable. USB is a finicky beast even if you stay within the lanes it was designed to operate in it. Just have a search of SC forums for USB issues. You'll get much better performance and reliable connection using a computer at the scope and remote to this computer if you want to have long range access and control.

-Chris

Re: Fast exposure / fps capture over gigabit possible?

Posted: Tue Jan 14, 2020 6:58 pm
by admin
Hi,

As Chris says, you are much better off keeping the computer close to the USB3 device and then remote controlling the computer. I have seen cameras running at around 300 to 350 MB per second of video data (ZWO174MC, QHY5III-178 for instance), which is way more than the bandwidth of gigabit ethernet. In fact for some cameras and add in USB3 card can be a problem because these add-in cards typically only use a single PCIe lane and the camera bandwidth can exceed the bandwidth of the PCIe lane.

Cheers, Robin

Re: Fast exposure / fps capture over gigabit possible?

Posted: Tue Jan 14, 2020 7:56 pm
by turfpit
If you are trying to extend USB and get it to work then have a look at:
https://www.startech.com/uk/Cables/USB- ... B3AAEXT10M
Cost is £135 for a cable and 2 can be daisy-chained to give 20m extension. The extender needs mains power, provided via the supplied AC adapter.

As suggested above (twice), the conventional way is to have a capture PC/laptop at the scope/camera and use a remote connection via another PC/laptop to manage the capture program. Software commonly used to achieve this would be Remote Desktop (Professional version of Windows) together with Remote Desktop Connection (look up RDP Server & RDP Client), TeamViewer or VNC.

VNC Server/Viewer software here https://www.realvnc.com/en/connect/download/vnc/.

Dave

Re: Fast exposure / fps capture over gigabit possible?

Posted: Tue Jan 14, 2020 8:41 pm
by markm75
Thanks all for the replies.

No i was hoping there was a hack to make this work if even via buffer, but honestly, i'm probably just as well off doing everything on the local mini pc (ssd D drive) in the nexdome at least for highspeed planetary.

I have 3 gigabit runs going to the dome, one goes to the mini pc. As of now all DSO and even some "slower" planetary was working fine over gigabit.

For nina and dso there is no issue, i can continue to send everything to my server location as before. But i guess for sharpcap ill just point that to the local d drive and run a push to the network as needed.

Re: Fast exposure / fps capture over gigabit possible?

Posted: Fri Jan 12, 2024 10:58 am
by Hibou
USB-3 extension cables mentioned by turfpit in 2020 have decreased in price in 2024. I tested the deleyCON 10m active USB 3.2 extension https://www.amazon.fr/gp/product/B0BMGSN7JS/ with the uncooled ASI432mm and ASI533mm cameras and was able to achieve the full 120 fps rate for the ASI432mm with full frame 1600x1100 8-bit pixels over 10+ meters without the need for additional 5V power, which is also possible with this cable, via an extra USB-A plug. This corresponds to ~1.7 Gbps, and seems perfectly stable - in my lab, not the field :-). 20 fps (2.5 Gbps) was achieved with the higher resolution 3000x3000 14-bit ASI533mm. The advertised throughput of this cable, limited by the USB A-type sockets, is 5 Gbps, though the real-life limit will be lower. This 10m cable is essentially two 5m cables with two amplifiers, and chaining two 10m USB 3.0 cables should also be possible. Tests were with an inexpensive NUC6CAYH celeron mini-computer with USB 3.0 type-A ports.

I have used FLIR (Point Grey) GigE POE cameras over very long distances, so I will explore usb3-ethernet adapters further. I have also used Rasberry-Pi front ends for ethernet cabling, and of course a simple front-end NUC PC. My requirement is simple, reliable long distance control and transmission, not necessarily high speed.