Remote Control Range

Here's my first report from the 2018 Nebraska Star Party. I realize it's now 2019, but better late than never, right?

In an earlier post I talked about exploring the ability to remote-control my imaging using a wireless router (the ASUS RT-N12) and Android tablet running TeamViewer. The theoretical range of this setup was 500m, and I posted a diagram showing a 250m radius around the anticipated imaging site:

This assumed I was going to set up on north end of the low hill north of the dinner shelter. I ended up imagining from a position further north (the blue dot in the diagram below):

The green dot is the location of the dinner shelter, from which one could see the setup point on the horizon. The signal there was strong enough to allow control of the imaging laptop. This is about 380m from the router. I did a little more exploring and found that at the yellow points there was good enough reception to be able to see the laptop display but not control it. The red dots indicate where the signal caused TeamViewer to give up.

I think it's fair to say if one can maintain a line-of-sight contact with the router the range of 500m is a fair estimate.

Modernizing my imaging setup

Yes, I'm finally going to move into the 21st Century by adding software mount control and plate solving! Along the way I'm consolidating all my cabling with both a 12V power hub and powered USB 3 hub.

I've resisted this move until now because it sounds really complicated and my imaging laptop wasn't up to running Astrotortilla. But the long winter gave me plenty of time and I've got a new laptop, too. And I have the motivation of doing something similar for the new imaging setup at the Minnesota Astronomical Society's Cherry Grove Observatory. (More about that in a coming post.)

What's New

• Power: My old wet lead-acid batteries have been replaced by smaller sealed AGM batteries, giving me a total of about 108Ah in the field (assuming an 80% discharge). This should be enough for four summer nights of imaging. The batteries can be connected in parallel.
• Software: BackyardEOS and PHD2 are now joined with StellariumScope, Stellarium, and Astrotortilla. ASCOM for everything, which permits me to do away with the cable from the guide camera to the mount! TeamViewer for remote monitoring and control.
• Cabling: A RIGRunner power hub and separate powered USB3 hub have been added. This means I only need to run one power cable to the mount, and one USB cable. All the cables now join securely using Anderson Powerpole connectors. A small DROK DC step down converter now acts as the power supply for my DSLR. This attaches to the power hub. 
• "Remote Control" via TeamViewer requires a wireless router for those times when the internet is available. I can control everything from my Android tablet.

ASCOM isn't nearly as difficult to implement as I had thought. Install the correct platform and drivers and you're good.

On the other hand, Astrotortilla has been a minor nightmare. The main problem has been the field of view that has to be specified. It really has to bracket* the FOV of your images. I have it solving now nice and fast, and working in conjunction with BYEOS and my mount.

*After running a lot of test cases I'm not so sure this is true. It seems like solving success mainly requires that the long axis of your image is slightly larger than the actual FOV. The short axis can be almost anything greater than zero and smaller than the long axis.

Almost 100%

Last night was just before full moon, which made it perfect for taking the "new" imaging system out and giving it a trial run. What makes it new? Here's a quick recap:

• New batteries connected in parallel
• A new DIY power hub and powered USB3 hub riding piggyback on the telescope along with the finder and autoguider
• A new laptop
• StellariumScope and Stellarium running the mount
• The latest version of PHD2
• Astrotortilla (AT) integrated with BYEOS
• ASCOM control of the mount and autoguider
• TeamViewer on the laptop to allow remote access to the desktop
• A Wireless router to allow connectivity for the remote access

Amazingly almost everything worked! Although AT was able to control the imaging camera correctly, no images were being passed to it by BYEOS (which did have its server mode on). I suspect some sort of interference between AT and Stellarium, so next time I will change my workflow.

I was able to take a first check of the router's range by carrying my tablet about 120m distant. I could still control the imaging laptop using it, and even snapped off a few pictures. I couldn't really walk any farther without adding obstructions to the signal, but given the imaging site was in a depression and not line-of-sight, I think 120m was a good start. It's almost got to be better at the Nebraska star party, where it will be broadcasting from atop a rise.

Remote Control of Imaging Laptop

It's still snowing here-15 inches last Saturday and Sunday, 2 to 4 more inches tomorrow. Naturally my thoughts have turned to Summer warmth. And where is the best summer warmth found? The Nebraska star party, of course!

Along with that warmth comes mosquitoes. They start coming out at dusk and can be pests the entire night. Your only options are hope for a good breeze, DEET up, or seek shelter. Breezes are not reliable, and DEET doesn't deter Nebraska mosquitoes from buzzing around your head. So option 3 is the most reliable, but how do you monitor your laptop while you're sitting in a vehicle or tent?

With TeamViewer you say! And you're correct, it's the remote access software of choice for many people in astrophotography. It's easy to use, powerful, and free for personal use. But it does come with one catch. As typically used it requires internet access. What do you do if you don't have that?

Conveniently, TeamViewer does permit a no-internet mode of operation. After you install it on your imaging laptop start the application and go to the menu's Extras / Options  dialog. Under "Network settings" change the Incoming LAN Connections to "accept exclusively," click OK and you're done!

(TeamViewer will now assume you're connecting to a LAN and will use the laptop's assigned IP address as "Your ID" on its main screen. Any other devices on the same router will now be able to connect with your laptop, even if the router isn't on the internet.)

Without the internet you need to set up some form of communication. I tried several methods to control my imaging laptop with my phone or tablet.

• Use the laptop as an access point, then have the controlling device connect to it. I couldn't get TeamViewer to work with this configuration.
• Use my tablet as an access point. Unfortunately my particular tablet couldn't do this.
• Use my phone as an access point. This worked, but turning on the capability required phone service to verify that it was allowed.  Since I don't have service at the Nebraska Star Party, this won't do for now. At other sites with service (like the Iowa Star Party) it may be the best option.
• Use a wireless router. This works perfectly. You don't need an expensive router for this, but there are a couple of considerations: the wi-fi bands used must be compatible with your devices; It should be reasonably waterproof on top to deal with dew, and you might want to look at the voltage requirement. I settled on the ASUS  RT-N12 ($20 from Amazon) that accepts 12V DC and can be powered directly from my batteries. The ASUS is found to consume a scant 2.3W which means it draws a tiny 0.2A.

The theoretical range of the ASUS is 500m, which would provide this coverage around my usual campsite (atop a very low rise) at NSP [CORRECTION: the red circle denotes a distance of 250m around the campsite, not 500m]:

ASUS Theoretical Range at NSP

Will it really be this good? I hope to do a little survey once I have it set up. if it allows me to see my laptop from Dob Row I'll be really pleased. If not, I'm quite confident it will easily reach my tent (maybe 3 to 5m away) and allow me to sit in mosquito-free comfort while imaging!