Can I use ASIAIR+ without wi-fi?

dean

I am going to the Green Bank Star Quest held at the Green Bank Observatory in WV. The Observatory is part of the National Radio Astronomy Network located in the National Radio Quiet Zone. The observing field rules state "no wireless devices".

If I connect my iPad mini 6 to the ASIAIR+ ethernet port with the correct cable...RJ45 to USB-C

Will the ASIAIR work?
Does plugging in the ethernet cable deactivate the ASIAIR wi-fi signal?

Dean

wvreeven

dean

Not out of the box. The reason is that the ASIAir and the iPad need to be in the same IP range and you'll need to configure that on the ASIAir. This requires ssh access to the ASIAir. See https://gist.github.com/wvreeven/2ba0d935d46c2068ad9c85ce17e12478 for how to do all that.
No. I don't know how to disable the ASIAir WIFI network.

w7ay

dean The Observatory is part of the National Radio Astronomy Network located in the National Radio Quiet Zone. The observing field rules state "no wireless devices".

Which is funny, since I read that there are now homes in Arbovale with WiFi :-). But yeah, you should observe radio silence all the way to Sugar Grove, even though I don't think the Navy has any listening equipment there any longer -- a Sputnik era thing.

I was at NRAO Green Bank for the summers of 1968 and 1969, as an NSF Undergraduate Fellow.

The skies are truly wonderful; you should see the meteor showers. Except for the strip mining, the entire West Virginia state is really beautiful country too.

Back when I was there, gasoline cars (spark plugs!) were not allowed past the gate to the radio telescopes. The observatory had specially modified diesel Dodge Darts (I think they were Darts, it was so long ago), and even they had specially shielded electric cables.

If I connect my iPad mini 6 to the ASIAIR+ ethernet port with the correct cable...RJ45 to USB-C

Yes, this will work just fine (IMHO, the fastest way to connect an iPad to an ASIAIR box). You can do this with both Lightning and USB-C iPads (I use both). With USB-C iPads, one of the dongles that I use is this:

https://www.amazon.com/gp/product/B00ZZ6NW5E

Bring along a 6 ft to 15 ft Ethernet cable. Test before you leave home. To also minimize RFI, use a shielded CAT6 if you can.

Once you connect to the dongle, an item called Ethernet will appear in the left column of the iOS Settings window (right below the WiFi settings).

There is nothing else you need to do. Raspbian will automatically connect to the LAN port, and the ASIAIR app will see the ASIAIR. With mine, the ASIAIR connected to IP address 169.254.232.xxx on the iPad.

The easiest way to disable a third generation ASIAIR WiFi from radiating is to use one of these 50 ohm SMA terminations in place of the antenna:

https://www.amazon.com/gp/product/B0719C1T99

Make sure you don't buy a shorting cap by mistake. They must be 50 ohms terminators. Don't leave the SMA antenna connector complelely empty either. A short and an open both present an infinite VSWR to the transmitter and not healthy to the transmitter unless it has full VSWR protection.

I have the above terminator permanently on my 3rd generation ASIAIR. I stay away from WiFi whenever I could.

BTW, connecting directly to a fast iPad can be additive. You may never use any other methods (even connected through home network) anymore. Downloads are definitely in the "augenblick" category :-).

(You can still find one of my reports in the NRAO archives:

https://www.gb.nrao.edu/electronics/edir/edir79.pdf :-)

Say hello to the Reber (you can't miss it, small cute 31-footer, painted red, white and blue :-), and Jansky (Bruce curtain, looks like a square wave with a reflector :-) antennas for me :-) Check the NRAO site map for Hannah House. That was the farm house where the summer students lived.

Pleasant memories from a lifetime ago. I was a Purdue EE undergrad then. After the second summer, I went to grad school at Stanford, and joined the Radar Astronomy group.

Chen

dean

Thank you both for quick and informative responses. I have ordered the suggested gizmo's and am anxious to do a test session. I will report results here.

Chen, re: Green Bank, same rules apply about gasoline engines (including cell phones, FRS radios and digital cameras) not permitted past the gate. There is an old Checker painted Air Force blue with an International diesel engine on display at the visitor center that was used to transport folks to the radio telescopes. My last visit was in 2019 (the pandemic cancelled the 2020 and 2021 Star Quest) and there were still a couple of 1970's era Dodge diesel pick up trucks regularly moving around the site. Also painted (a now very faded) Air Force blue. I was fortunate to be able to snag a tour to the top of the GBT during the 2019 visit. Incredible experience. I know Reber, I know Jansky and will pass your greeting along.

I was also a regular visitor to Sugar Grove when it was active. I made many motorcycle touring trips to that part of WV in the 1990's. I am US Army retired so had access to the recreational facilities (really nice fully furnished cabins) on the Navy base. So strange to be driving in the mountains for hours then seeing a NAVY water tower. 😀

Dean

w7ay

dean So strange to be driving in the mountains for hours then seeing a NAVY water tower.

Dean, the Navy was also responsible for dirigibles. Don't need to be anywhere near water for them either :-).

I used to drive into the Navy's Moffet Field in the SF Bay Area to get to the NASA Ames Research Center that is sited within the base, past the old gigantic hangars that used to house the airships (oxymoron). It was a pain to return the bumper sticker when I changed car -- the remains that I scraped off my bumper were in small pieces that I had reconstituted on a cardboard :-). There was an entire car bumper hanging in their security office from some person who could not remove the sticker and had handed them the entire bumper :-).

By the way, Sugar Grove was infamous for a gigantic radio telescope that was never compeleted. In the middle of constructing it, they discovered that the main RA bearing was not going to be large enough to handle the entire telescope, so they scrapped the project and buried the bearing :-). What mil folks call a SNAFU :-).

But then, the civilian NRAO 300 foot transit radio telescope (can only be moved along the prime Meridian) also eventually came crashing down some years ago. That was one impressive telescope when it was tilted fully to the south, and you walk right to the edge of the dish.

By the way, Sebastian von Horener was one of the astronomers who designed the GBT. It was in the design stages when I was at Green Bank. I still remember how my undergraduate jaw dropped when I heard him describe how that telescope flexes. In the past, telescopes were built to be as stiff as possible, so that there is no flexure as you track an object across the sky. That made them heavy and expensive. The GBT is actually designed to flex. However, the dish surface flexes from one paraboloid into another paraboloid! The feed antenna position is programmed to change focus position depending on where the telescope is pointed, but the efficiency of the antenna did not change.

The next time you see the GBT, just imagine in your mind's eye that the entire mass is flexing!

We should mount our guide scopes so that they flex, but still pointed paraxial to the main OTA :-).

Chen

dean

Yay! Daytime test only so far but works perfectly with your recommended gizmo’s. Ready for ' Green Bank!
Again, thank you both for chiming in.
Dean