Multiple Raspberry Pis and VirtualHere for Remote Observing

[badgerchap]

Just thought I'd share my experiences of trying to put together a remote setup, which I'm implementing to keep my tootsies warm as winter approaches. The main reason I'm writing this down is so that others can see my setup in case they're looking for a similar implementation.

 

So I'd heard that people had tried using a Raspberry Pi as a server running VirtualHere to control their mounts and cameras from the warmth of their living rooms. There were two main problems that I'd seen, as follows:

1. The RPi isn't really quick enough to handle the traffic for the entire setup

2. VirtualHere only allows the connection of a single device without purchasing a licence.

 

Well, I decided to kill two birds with one stone - multiple Pis!

Each Pi acts as a VirtualHere server and as such, shows up as an individual USB hub in the VH client (which I'm running in Windows on boot camp on an iMac - three OS's is one day, yay!) This means that you may use one device on each Pi without needing a license.

 

Now obviously this is only useful if you have spare RPis hanging around - otherwise you might as well just buy an RPi 3 (quicker than earlier models) and a VirtualHere licence.

 

Each Pi used will require its own power source, so be ready for some spaghetti. You also need to be aware of the range limitation on the Pi3's wifi adapter - I had to move mine a few inches closer so that the connection was stable. I do have a more powerful dongle adapter on the way which should help with this.

You also need to be aware of latency when taking images - I set the DSLR imager to store the images on its own SD card rather than transferring to the Pi, but the latency is still noticeable. However, APT (which I was using for capture) just waits a bit longer between images. TBH this is quite useful as it gives the setup a chance to settle down from any mirror related vibrations!

 

As for guiding, I can't tell you the results yet as it's a full moon tonight, so I haven't tried anything DSOey yet. That will come. However, tracking and GoTo functioned well, so I think Autoguiding should be OK - I've connected the camera (QHY5v) in the daytime and I got a moderate frame rate which I suspect will be sufficient for PHD.

 

The big limitation in my design is the lack of an electric focuser, so until I can buy one of them, I have to run outside and tweak repeatedly until it comes right. My plan is to drive the focuser via the RPi's GPIO pins. I might build this myself but the only steppers I have are salvaged from an EQ3 and are really very slow.

I will most likely buy a VH licence soon, but whether or not that will then allow sufficient data transfer and control speeds through a single RPi 3 remains to be seen.

 

Anyway, hope this proves useful to someone somewhere. I'll update it when I test the autoguiding and (hopefully) the focuser.

[safaritn]

Hi badgerchap,

I'm very interested of your idea, but one question : how to connect to multiple Raspebbry Pi ? If there is multiple Wi-Fi connection, which one must we use ? I think that is one Wi-Fi network and the Raspberry Pi are connected with LAN wires !!!

Your sincerely,

Hedi