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Archive for March, 2016
Posted by smoothvirus | Mar 05, 2016 @ 12:07 PM | 20,491 Views
So I have been flying FPV for going on three years now, and thought I understood what the Fresnel zone was, but as it turns out, I was completely wrong. I thought the FZ was something you "flew into", as in, flying behind a building on 5.8 would be "flying into the Fresnel zone." Alas, this is completely incorrect.

I was doing some web surfing on the FZ and stumbled across this illustration:

..and BANG! I realized I have been wrong all along about what the Fresnel zone is.

The definition from that site is this:
The Fresnel zone is a football-shaped space between two transceivers – the longer the distance and the lower the frequency, the further across the Fresnel zone is.
Of course, for our application, the FZ would be a football-shaped space between a transmitter and a receiver.

I found this site useful as well, for visualizing what is going on.

Since I tend to be a very visual person, I made a quick illustration of what I think it might look like if you could actually see the FZ from the point of view of your video receiving antenna. Please forgive the MS Paint cartoon version of my flying site, and I can't claim that it's completely scientifically accurate.

So, in my illustration there are two FPV aircraft flying at the same distance away from the receiver. One has a 1.3ghz VTX and the other has a 5.8ghz VTX. The FZ would probably look a bit more "swirly" if I was using CP...Continue Reading