Wifi channels


The Raspberry Pi3 has wifi built-in. Unfortunately, it cannot see my wifi network.

I am using my Mlais M52 phone as a wifi hotspot for Internet access. Running SNS (Simple Network Setup) in Quirky Xerus on the Pi3, a scan shows three neighbours wifi networks, but not mine.

This is very mysterious. I did encounter this problem with a friend's laptop when she visited my place, running Windows 7 or 8, a year or so ago -- never found out why.

I reported this on the Puppy Forum, and forum member 'pakt' replied that his Mlais M52 worked:
http://murga-linux.com/puppy/viewtopic.php?p=922692#922692

Frustrating! But note something in his post: his hotspot is using channel 11.

I am not the only one who has experienced this problem with the Pi3. This is a post, which also identifies the cause of the problem:
http://raspberrypi.stackexchange.com/questions/46626/rpi-3-doesnt-see-my-wifi

...channels 12 and 13 don't work!

I haven't checked yet, but it is highly likely that my hotspot is using channel 12 or 13. Now, I could change the channel on the phone, or I suppose that's possible, haven't looked into it yet.

However, the above link states that installing the 'crda' DEB package fixes the problem.

Here is a very useful link, that explains about crda, and how to set it up in Linux:
https://fitzcarraldoblog.wordpress.com/2013/01/20/setting-the-wireless-regulatory-domain-in-linux-on-your-laptop/

You need to tell Linux what country you are in, using crda (and you need the 'iw' package installed), so the wifi will use the channels allowed in your country.

Here is further information on the two-character country codes:
https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2

I think that what I need to do is add selection of the appropriate country-code somewhere, maybe in QuickSetup.

Note, the Linux kernel needs to be configured to support crda.


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