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Wireless switch 700 foot range  XML
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tictoc



Joined: 03/02/2015 13:42:39
Messages: 2
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Ok,

I was pointed to this site by stevech.

What recommendations of parts for a simple pressure switch to turn on a
pump relay circuit 700 foot distance.

Thank you

andy
stevech



Joined: 07/07/2014 18:07:27
Messages: 91
Offline

can you get line of sight or nearly so? How obstructed might the path be for practical antenna heights (say, 15 ft)?
tictoc



Joined: 03/02/2015 13:42:39
Messages: 2
Offline

Thanks for the reply stevech,

Yes I can easily get line of sight heights on both ends.
One concern is how much cable length I can run from transceiver to antenna.

thanks,
andy
stevech



Joined: 07/07/2014 18:07:27
Messages: 91
Offline

It's all about frequency and choice of coax cable.

The very best solution is for radio and antenna to be collocated. A weatherproof box on top of the mast. Low voltage cable with DC power up the mast (or tree or rooftop). Coax is 1 ft long. Or 0 ft. if you can get away with a "rubber ducky" antenna's gain.

At 900MHz RG8 coax is normally used to connect to a small omni antenna or yagii. Short coax. Pre-made cable w/connectors.
At 2.4GHz, 6 inches or so of LMR400 or some such. But most often, in a point to point bridge link, one uses a 1 ft. square weatherproof box that is on one side, a patch antenna and the radio is inside, with cat5 or some such cable down.

The first thing to do is a link budget. Simple math.
Need site survey...
Path length to 10%. Can use Google Earth or other means.
Verify clear line of sight visually - binoculars. If not clear, photo and description- terrain vs. trees vs. man-made structures.
We then choose the required antenna heights at each end.

Now the math and prediction
Then we do path loss calculation with a spreadsheet that has embedded formulas. I have such. Do for two freq. bands.
Then we choose some radio products for one or both bands. Plug into the spreadsheet their transmitter power and receiver signal strength required for your goal data speed.
We then see how much extra antenna gain is needed, if any.
We include at least 10dB margin for fading and link reliability.

At 700 ft. it'll be pretty easy.

Glad to help with this if you can provide the site survey info as above.
 
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