After years of sleeping first in a tent and then in the back of my van at star parties and dark sky excursions, I finally decided to go in style with an RV. My plan is to sit inside my nice cozy RV with my laptop and control my telescope, cameras, etc. wirelessly with WiFi. I bought a Beelink U57 mini-pc which sits at the telescope and runs all my software while I remotely log into the mini-pc with my laptop inside the RV. The mini-pc is headless (i.e. has no display to suck power) and therefore draws an order of magnitude less power than the laptop would running the same software. I can use the laptop as a terminal inside the RV and, with proper shielding, be able to view images on the screen unfiltered without disturbing anyone else with the light from my computer. Also, if I need to conserve power I can let the laptop go to sleep as I only need it to check in on the mini-pc's progress if I am doing a long imaging run. If I am doing EAA (camera assisted viewing), I will to use the RV's power to keep the laptop running during a session.
Up till now I set up inside an EZ Up shelter with side curtains and with the pc shielded so that the light is minimized. I use a 32ft active USB3.0 cable between the scope and the laptop for connectivity. I could do the same with the RV running the cable through a partially open window but I want to minimize the use of cables which are easily tripped over in the dark. Instead I decided to find a portable wireless router which can provide a reliable connection throughout the night from inside my RV to my rig outside. And since I may not always be able to park right next to my scope, the longer the range of the router the better. The router needs to run on dc and require as little power as possible. So when I read about the GL.iNET GL-MT300N-V2 Wireless Mini Portable Travel Router for less than $20 ($27 these days) I decided to give it a try. At this price I figured there was not much to lose. This mini router is less than 2.5" square and about 1" tall with a bright mango yellow plastic case weighing less than 2 oz.. It has 2 Ethernet ports, 1 USB2.0 port, a Micro USB port for input power and 128Mb of RAM. It uses 5V/1A so it can easily be powered by one of the USB ports on my mini-pc and draws less than a couple of watts of power by my measurements. It comes with an Ethernet cable and a USB2.0 to Micro USB cable which connect to my mini-pc, a Beelink U57 with an Intel Core i5-5257u Processor. It has LED lights to show that it is powered and has a reset button and a mode switch. The GL-MT300N-V2 only supports the 2.4G band at 300Mbps and not the faster 5G band. It can function as a portable router, mobile hot spot, WiFi repeater bridge or range extender. I only need it to function as as a portable router to set up its own WiFi network which I can connect to from my laptop inside my RV. The setup was simple and straight forward with the included instructions. You simply apply power to the router and it begins broadcasting a WiFi signal. You connect to the WiFi with the default password printed on the bottom of the router which is simple to change once connected. To access the router settings you simply connect to the IP address in the instructions. This will take you through a screen to choose your language, a screen to change your Admin Password and finally to the main page with access to an Internet, Wireless, Clients, Firewall, etc. pages where you can change settings for each of those if desired. For my application using this as a wireless router, the only thing I needed to change was the password. Closing out the connection to the router I was set. Then I simply connected the router to my Beelink mini-pc with the Ethernet cable and powered up the router with the Micro USB cable also connected to the mini-pc. Now I could see the GL-MN300N-V2 WiFi signal on my laptop and connected to it using the password I had just created. To connect between my laptop and the mini-PC I use TeamViewer but you can use Remote Desktop or any other such software.
Since I do not have my RV yet, I set about to test the quality and stability of the wireless connection with the GL-MT300N-V2 connected to my Beelink mini-pc inside my observatory and my laptop setup in the back yard at different distances from the observatory testing the connection at successively longer distances. Once connected, I observed how long it was able to maintain the connection while performing a dummy astrophotography run with the telescope tracking and the camera taking exposures of 1 minute duration while watching progress on my laptop. The objective was to find the maximum distance that a a continuous connection could be confirmed for at least 8hrs. At 75 ft I could not get a connection at all. At 65 ft I could connect to the wireless network but the connection would drop repeatedly. I was able to maintain a solid connection at a distance of 60 ft to the Travel Router inside the observatory without dropping for in tests of up to 8 hours. I repeated this test two more times and satisfied myself that I could reliably maintain a connection through the observatory walls at a distance of 60 ft. In addition to maintaining a solid connection I tried opening files and changing settings in The Sky X (TSX) running on the Beelink mini-pc. At 60 ft I did not see any issues of a sluggish or poor connection. Keep in mind that the quality and stability of the connection depends both upon the Travel Router's wifi strength and also on the strength of the wifi hardware inside my laptop. Other laptops or pcs may support longer or shorter distances than mine. Also while the wooden walls of the observatory are not the same as the fiberglass and aluminum walls of my RV I expect that I will be able to connect reliably to my telescope out in the open at a similar distance. Encouraged by the 60 ft distance I tested the connection from inside my house on a straight line of sight through glass doors to the observatory only 40 ft away. While I could make a connection it would always drop within an hour or less so I deem this unreliable for a connection through a pair of walls or other multiple obstacles.
Although the GL-MT300N-V2 worked well for my application and I think it will serve my needs in the field I wanted to try a slightly more expensive router from the same company equipped with a pair of antennae to presumably provide greater distance capability along with 5G (433Mbps) for faster connection speed. The GL-AR750S-Ext travel router sells for $54.90 and comes with 3 Ethernet ports, a USB2.0 port and a micro USB port for power input. It also has LEDs for power, 2.4Ghz and 5Ghz WiFi signals, 128Mb of RAM, a reset button and a mode button, a micro SD card slot and 2 antennas which can be rotated from the compact travel position to 90 degrees during operation for better signal range. This router is also quite compact with dimensions of 3.9 x 2.7 x 0.9 inches with the antenna folded down and weighing only 3 ounces. It has over 1600 reviews on Amazon with 89% of them rated 4 or 5 and only 7% rated 1 or 2. Setup is the same as for the GL-MT300N-V2.
I performed the same tests as with the GL-MT300N-V2 above. In this case I could reliably connect at a distance of 100 ft from my observatory at 2.4G for repeated tests of 8 hours and longer. 100 ft is the maximum distance I can be from the observatory in my back yard so it is possible this will work at a longer distance. Using the faster 5G connection, although I was able to make and maintain a connection repeatedly at 100 ft for 6 hours or longer, several times I had trouble making the initial connection and multiple times the connection dropped around 6 hours. It is well known that the higher frequency of 5G does not have the range of the lower frequency 2.4G so this is not surprising. The higher frequency signal has more difficulty penetrating walls. Tests from inside my house confirmed that I could not obtain a reliable connection at 5G but could easily maintain a connection all day long at 2.4G. This is at a distance of about 50ft from inside my house to the router inside the observatory. So it is clear that the GL-AR750S-Ext can provide a wireless connection at a greater distance than the GL-MT300N-V2. This is not a surprise since that is obviously the point of the antenna. I did not test transfer speeds or other performance metrics as I merely want to be able to remotely control the mini-pc and keep an eye on an imaging run with the laptop remotely. I did test downloads of data which worked without a problem over this WiFi network but did not try downloading images as they are captured as that is not my objective. As I mentioned above, differences in the wifi antenna of the laptop or pc being used, local interference from neighboring wifi signals and even RF interference from electrical equipment like a microwave can change the distance at which a reliable connection can be made and/or cause connection disconnects. As far as my tests, I think either travel router will work well for my application with the GL-AR750S-Ext giving me a greater distance capability. I would recommend either so long as your situation is similar. Links are Amazon Associate links.
1 Comment
Bruce
3/14/2021 04:22:03 pm
With the Lithionics lithium phosphate batteries the recommendation of not having the batteries at more than 50% SOC is for situations where they will not be discharged for a period of more than 3 months. For storage of many months without use they recommend charging to 100% every 6 months and then discharge to LVC and then recharge it back to 50%. For astrophotographers it is not to be expected that a battery pack will sit for 3 or more months.
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