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Computers & Hardware => Networking => Topic started by: tickmike on December 18, 2015, 10:34:54 PM

Title: Animation showing how wifi travels.
Post by: tickmike on December 18, 2015, 10:34:54 PM
Animation showing how wifi travels.

https://media.giphy.com/media/1QEug4vpG5CCs/giphy.gif
Title: Re: Animation showing how wifi travels.
Post by: ryan2390 on January 21, 2016, 01:34:35 AM
Very clever and probably quite accurate.

Whilst I don't know much about propagation at those frequencies my own experience with VHF and UHF as a radio amateur have shown that things like this do not always behave as they should.

If I had the know how I'd love to see just how far wifi will actually go. Same power levels but with directional antennas. A future experiment maybe?
Title: Re: Animation showing how wifi travels.
Post by: JGO on January 21, 2016, 10:16:12 AM
Very clever and probably quite accurate.

Whilst I don't know much about propagation at those frequencies my own experience with VHF and UHF as a radio amateur have shown that things like this do not always behave as they should.

Suggest that this should be "  don't always behave as elementary student textbooks say they should The laws of nature are not derived from books, it is the other way round ! 

Since there seems to be little or no metal in the walls of the example it seems to be battery powered equipment in a log cabin  ? Even then cutlery is big enough to act as a reflector !

Title: Re: Animation showing how wifi travels.
Post by: jelv on January 21, 2016, 11:41:27 AM
If I had the know how I'd love to see just how far wifi will actually go. Same power levels but with directional antennas. A future experiment maybe?

It's been done - look up cantenna. People have achieved a range of over a mile.
Title: Re: Animation showing how wifi travels.
Post by: tickmike on January 21, 2016, 02:28:28 PM
I had a WiFi link to the local village school some years ago and that was about 1Kl using two WiFi dongles mounted in old satellite dishes and worked very well so I could do remote network maintenance.  ;D
Title: Re: Animation showing how wifi travels.
Post by: sevenlayermuddle on January 21, 2016, 02:31:36 PM
It is very hard to predict, IMO, the long range 'fringe' propagation range of any radio device, and risky to assume that what works one day will work the next.

As a kid in the 70s, I had an old dual-standard TV set that I'd modified to operate on 625 lines at VHF, the opposite of UK, but as used then by most European countries.  At the right times, using just a normal set-top antenna, I could get a good and stable picture from as far afield as Russia and Spain.  The trick to wait for a transient phenomenon called 'sporadic E', which is efficient reflection from the ionosphere.    Five minutes later of course, the signal had usually evaporated into noise - but I still have a few trophy photos I took of foreign test cards.  :)
Title: Re: Animation showing how wifi travels.
Post by: ryan2390 on January 30, 2016, 02:00:42 AM
It is very hard to predict, IMO, the long range 'fringe' propagation range of any radio device, and risky to assume that what works one day will work the next.

As a kid in the 70s, I had an old dual-standard TV set that I'd modified to operate on 625 lines at VHF, the opposite of UK, but as used then by most European countries.  At the right times, using just a normal set-top antenna, I could get a good and stable picture from as far afield as Russia and Spain.  The trick to wait for a transient phenomenon called 'sporadic E', which is efficient reflection from the ionosphere.    Five minutes later of course, the signal had usually evaporated into noise - but I still have a few trophy photos I took of foreign test cards.  :)

There is still some analogue TV Somewhere around 40-48MHz I believe. One of the guys from my radio club still has an old set and a VCR connected just in case. Sporadic-E is a brilliant phenomenon. Speaking to British radio amateurs with a directional antenna pointing towards Europe on 50MHz is an experience I will never forget