Camera connection speed requirements

[sophiecentaur]

I was having some problems with my ZWO ASI290MC connection to my MacBook Pro and suspected a cable fault. So that was why I contacted ZWO and asked about how I should actually be connecting my kit to the computer.   I wanted some helpful advice about a reliable adaptor to connect my ZWO usb3 B to the Thunderbolt sockets.  Also, how to connect to somewhere warm, indoors. They recommended using their own ASIAIR wifi system, having told me that they would not recommend  more than 2m of cable link.  (That's pretty impractical for most people, without an Obbo.) I'm sure they could do better than that, with appropriate data coding, despite their HD imaging requirement.

I don't  know about experiences of other members but home wifi can be very problematical. I really don't want to invest in a wifi hub for the garden if I can't be sure that it will actually do the job. I have two options for a control base. One is the nearby shed which should need a bit over 3m of cable and the conservatory, which is more like 10m away but would be much more cosy and comfy. 

A 10m USB cable (or perhaps more than one) would be ideal but the probable performance would be predictably poor - wifi would be an unknown quantity. (USB repeater?)

I would love to know what other members use for longish connections. Images and movies can present high data rate demands.

[symmetal]

The maximum data transfer rate for USB3 is much faster than can be achieved using Wi-Fi or even wired ethernet. USB3 is 5Gb/s while gigabit ethernet is 1Gb/s. These are theoretical maximum speeds and you won't normally achieve them in real life. 3m of good quality USB3 cable is generally accepted as the maximum length to allow its maximum speed.

You can get active extenders, up to 15m or so, to get USB3 to work over longer distances but these greatly reduce the actual data speed, even though they claim speeds 'up to 5 Gb/s'. A member here did tests with 5m and 15m active extenders, and they both limited the speed when transferring hard disk data to the same value of 60MB/s. This is 480Mb/s, 1/10 the speed of USB3 limit and the same as the upper limit of USB2.

For normal imaging, and not planetary using video, this is not too much of a problem and works fine. For planetary imaging this will be a bottleneck and limit your maximum framerate. In your case you could do normal imaging from the conservatory, and planetary imaging from the shed. 🙂

Having a small computer at the scope, like the ASIair or a mini PC, to do the imaging, connected via Wi-Fi or ethernet to your indoors computer removes these imaging data transfer constraints, as the scope computer can record at full speed and transfer the data to the indoors computer later, at a slower speed, when required.

Alan

Edited October 30, 2020 by symmetal

[sophiecentaur]

On 30/10/2020 at 16:16, symmetal said:

Having a small computer at the scope, like the ASIair or a mini PC, to do the imaging, connected via Wi-Fi or ethernet to your indoors computer removes these imaging data transfer constraints, as the scope computer can record at full speed and transfer the data to the indoors computer later, at a slower speed, when required.

Alan

That's not a bad idea and I could  use team viewer to control it (from the cosy conservatory). There seems to be no easy way to do astrphotograpy. Doing it electronically needs (a minimum of)  four separate data connections needed for mount, images, filter and focus plus my system could need to use two (or at least one and a half) computers, connected by wifi or some cable arrangement. Then there are the other basic problems that all telescopes encounter and, in an automatic system, you could go away and come back in a couple of hours and find that you got only 30s worth of usable data. All that's fine if you have 'professional' resources and budget but, on a shoe string -- yoy yoy yoy.

"The maximum data transfer rate for USB3 is much faster than can be achieved using Wi-Fi or even wired ethernet. USB3 is 5Gb/s while gigabit ethernet is 1Gb/s.

Also true. USB is only fast when you are using devices that are almost as close to the computer as the internal ones! Data transfer speeds is a subject like HiFi, that has more promise than delivery.

[symmetal]

5 hours ago, sophiecentaur said:

That's not a bad idea and I could  use team viewer to control it (from the cosy conservatory).

Yes, I have a mini PC and power interface mounted next to the scope so they move around with the scope and almost all the cables attached to the scope and accessories don't need to dangle down to a box attached to the mount and possibly get entangled. Just the main DC power cable and an ethernet cable goto a small interface box fixed to the mount which I connect to, along with an EQDirect cable from the scope PC to the mount. 🙂

I use Windows Remote Desktop to connect from indoors or there are several other ways to do it, like TeamViewer as you say, though some people have had the Teamviewer free connection option disabled as it was suspected it was being used for commercial purposes. 😒. I also use TightVNC for remote control of those PCs not using Win 10 Pro.

The ASiair uses a Raspberry Pi running Linux so is a bit more involved controlling it from a Windows PC, but several here do that and can give you more information if you need it.

Alan

[sophiecentaur]

17 hours ago, symmetal said:

Yes, I have a mini PC and power interface mounted next to the scope so they move around with the scope and almost all the cables attached to the scope and accessories don't need to dangle down to a box attached to the mount and possibly get entangled. Just the main DC power cable and an ethernet cable goto a small interface box fixed to the mount which I connect to, along with an EQDirect cable from the scope PC to the mount. 🙂

I use Windows Remote Desktop to connect from indoors or there are several other ways to do it, like TeamViewer as you say, though some people have had the Teamviewer free connection option disabled as it was suspected it was being used for commercial purposes. 😒. I also use TightVNC for remote control of those PCs not using Win 10 Pro.Alan

I was going through all the available options for me - that are cheap or free. I then realised that, with Apple, you have Screen Share which is universal and free!!!! So I have already managed to use my nice big screen iMac to control the macBook. And again, I have an elderly Mac mini (2011), which would fit right on the mount. The only question is whether its usb2 ports on the mini are quick enough. But there is another possibility in the form of an Apple Thunderbolt outlet on the mini which, they say, give fast connectivity to a range of (fast USB) peripherals. It may be worth getting hold of an adaptor and just trying that out. It would be a cool solution, requiring only a memory upgrade for the mini. 8GB should do it for less than £30. 

Having been moaning about using Windows and the far from friendly ZWO ASIstudio etc. it was such a nice experience just to 'enable screen sharing' on a Mac and to connect the other Mac via the normal Network display. There was the other screen, visible  and everything worked as if I was using the remote machine. 

An yet people 'hate Macs'. I can agree that a developer can get on far easier with a PC but it's 'users' who object to Apple. It's big endians and little endians all over again. (See Gulliver's travels)

[symmetal]

32 minutes ago, sophiecentaur said:

I was going through all the available options for me - that are cheap or free. I then realised that, with Apple, you have Screen Share which is universal and free!!!! So I have already managed to use my nice big screen iMac to control the macBook. And again, I have an elderly Mac mini (2011), which would fit right on the mount. The only question is whether its usb2 ports on the mini are quick enough. But there is another possibility in the form of an Apple Thunderbolt outlet on the mini which, they say, give fast connectivity to a range of (fast USB) peripherals. It may be worth getting hold of an adaptor and just trying that out. It would be a cool solution, requiring only a memory upgrade for the mini. 8GB should do it for less than £30. 

I should have realised you had a Mac when you mentioned Thunderbolt in your first post. 😀  The USB2 ports will be OK for normal imaging,  just a slower image download time, the frame buffers in the newest ZWO cameras sorted the USB2 transfer issues. For video of course they will be limiting the frame rate quite a lot with a sizeable ROI. A thunderbolt to USB3 hub should work fine I imagine, though I have no experience of using one. Hopefully someone else who has one can confirm.  Your solution otherwise looks good. 🙂

Alan

Edited November 2, 2020 by symmetal