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Raspberry Pi wifi issues

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#1 astrokeith



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Posted 24 June 2021 - 08:20 AM

I was doing some testing today, and had the RPi4B sitting on a metal surface. It was only about a metre from my Nexus DSC, and it refused to connect. (RPi as client)


It was showing full strength signal from the Nexus, but wouldnt log-on. Went in a loop keep asking for password and then it gave up.

Tried it with some other wifi sources - all the same.


Tried another RPi, identical problem.


Both had previously connected to the Nexus countless times.


Moved the RPi off the metal surface - instant connection.


The metal surface wasnt in-between  the RPi & wifi source. The Pi is in a plastic case and just within about 5-8mm of the metal surface and the Nexus was way above the surface. The metal surface wasnt grounded.


I know the RPi wifi antenna is 'pants' and I usually only rely on 2-3m range. But this behaviour was a bit of a surprise (and explains a few things!)


Mounting a RPi on a metal telescope may degrade the wifi more than you would expect, even though it looks like full strength.

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#2 paul.ibbitson


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Posted 24 June 2021 - 08:37 AM

I found the perfect place for my PI last night.

It fits nice and tight in the red dot finder bracket. It stayed there for the whole imaging session and I had no connectivity issues at all.

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#3 NearVision


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Posted 24 June 2021 - 05:30 PM

A possible answer...


The metal surface will act to block signals and for WIFI to work the rPi and the Nexus DSC need to have a strong enough signal sending and receiving. When you check the signal strength it's only telling you how strong the signal that it's receiving is. If the rPi isn't getting enough signal you won't be able to maintain a solid connection. Try checking the signal strength on both devices. I've seen that with laptops trying to connect to a hotspot that's too far away. The hotspot is sending a very strong signal so I see a great connection on my laptop but my laptop isn't transmitting nearly as much power and the hotspot receiver isn't sensitive enough so the connection keeps dropping or never completes. If your rPi is in a metal case the signal can only get out through the holes in the case and the metal mounting plate could block some and create a very effective Faraday cage!


The wireless equipment in rPi's, their cousins (ASIAir, StellaMate, ETC), isn't the strongest. It works well within it's range but don't expect high performance just like you probably don't expect the rPi to do post processing on the photos. I've got a AZ-GTI mount that has a small WIFI setup builtin and the connection to my phone will drop pretty quickly as I move away or even to the other side of the mount.


One work-around is to get an external WIFI adapter with an antenna. The antenna is then outside of the rPi case and usually at right angles to the metal plate it's mounted on. Of course it's 1 more piece of equipment to carry around/setup/watch out for.

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