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New OSD from RangeVideo


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#21 W3FJW-Ron

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Posted 12 July 2008 - 01:06 PM

I think most JR receivers are single conversion but I've never heard any problems with range. Mine is much farther than I can see the plane however I have no Idea what the max range is. I'm on 72 and know when the band conditions are right the range can be in the thousands of miles (not too helpful though. Just to give an idea of how the sig can be affected). A mmic could be used as an RF amp for the Rx with a little construction time....
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Ron

#22 apocza

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Posted 17 July 2008 - 12:11 AM

Hi,

Well my plan is to just use longer antennas...I live on top of a hill and have clear line of sight for quite some distance...just a few trees on the one side im worried will cause a problem...so What about a long aerial on the roof? I will only fly from the roof so dont need it to be portable..I saw the patch antenna from Rangevideo I might get for the rc cam, but for the radio control Might be able to just use a long aerial from a radioshack shop? Or am I way off here? If you have straight line of sight, at what est. distance should you lose control of the plane? With a standard JR 2610 radio?

Edited by apocza, 17 July 2008 - 12:12 AM.


#23 W3FJW-Ron

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Posted 17 July 2008 - 04:24 AM

It sure does sound like you have a great place to take off from... The trees won't bother you unless of course, you let them get between you and the plane. Then the signal from the plane will be absorbed by the trees and vice versa. Long pieces of wire for the Rx are fine but if used for the Tx you will have a problem. The Tx has to be matched reasonably well to the antenna or you'll have standing waves that will be reflected back to the Tx and will probably cause it to heat up and kill it. I don't think any of these transmitter modules have any sort of protection against high SWR (Standing Wave Reflection).

Can't give an estimate of distance. If the JR is on the 72mhz band, you will lose your video before you lose control of the plane given that your video Tx works on a frequency above 1ghc. There are too many variables such as humidity, rain, the sun, possible multipathing, power output of Tx, etc. A FPV won't be of any use at that point. The only thing that could save the plane would be an automatic GPS based system to return to home on signal (72mhz) loss. Some Amateur Radio Operators in Georgia have gotten over 30 mile point to point (mountain top) ranges on wifi equipment without modification to the units except for antennas. I would imagine they used parabolic dishes as the wifi signal is in the 2.4 ghc band also.
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I think I might just go into the antenna building/selling business. I've never understood why a patch antenna should cost as much as they do. I think half of what they are selling for or even a little less would be a fair price. The profit most certainly is a few hundred percent.

I hope this helps you understand some of the basics that pertain to radio frequencies, specificaly 2.4ghc. Good luch with your project. It most certainly rewarding when you can see it working.....
73
Ron