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Belyivulk
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400km + Link

Sat Mar 08, 2008 12:40 am

Hi All,

We plan to take a shot at making a link of 400km or more :) What we need! is a someone who can tell us, or give as a link to, a calculator that can work with links over 160km. We specifically need to know what elevation we will need at either end in order to make the link work (theoretically). I imagine that at 400km the curvature of the earth is quite a consideration more than anything else.

It is our intention for the vast majority of the link to be over water as well. What should we know that we dont already?

One end is likely to me 2000m above sealevel, and the other end anywhere from 400m -> 800m (is the highest point we have available).

**edit** I should probably mention we do have a fair amount of experience with shorter links (60 - 100km), and this 400km link is purely a test & a shot at the record :)

Cheers!
 
jonbrewer
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Re: 400km + Link

Sat Mar 08, 2008 9:59 am

Seeing as the EIRP limit on a P-P link in New Zealand is 200W, I somehow don't think you're going to make 400km.

An XR5 (28dBm) is not legal on anything higher than a 26dBi 600mm dish, unless you have a lot of cable loss in the system.

That said, if you post the coordinates (NZMG please) I'm happy to do the path study and post the results.
 
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Belyivulk
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Re: 400km + Link

Sat Mar 08, 2008 12:20 pm

i am aware of the limits. as stated there is no intention for the link to be perminant :) more just a 'what is possible'
 
danletkeman
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Re: 400km + Link

Tue May 06, 2008 6:08 am

What are the GPS locations and the antenna heights?
 
danletkeman
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Re: 400km + Link

Tue May 06, 2008 6:54 am

Just a quick look at the elevation data, it looks like there is a possibility of a 341km link (if those places are accessible).

Otherwise I don't see that there are any possible locations.
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RK
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Re: 400km + Link

Tue May 06, 2008 7:28 am

At a distance of 367 km, earth curvature is 2000m in the middle.
In short, you can't even get close to 400 km.
 
jonbrewer
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Re: 400km + Link

Wed May 07, 2008 1:49 pm

If you want to play at 400km, grab a Ubiquiti XR7 and try for troposcatter.
 
Tanker
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Re: 400km + Link

Wed May 07, 2008 2:00 pm

At a distance of 367 km, earth curvature is 2000m in the middle.
In short, you can't even get close to 400 km.

...... damn!!!!! - there I was thinking the earth was FLAT!!!!! :shock:
:D :D

Ah well... We'll just have to use "hoppers" and repeaters....

I don't want to even let my mind wonder into the relms of "visiting" - or repairing a BSS 400Km away from me!!
Our futhrest BSS is 140Km away and we have scheduled 3 days a year to "visit" it... so far so good.

T
 
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Belyivulk
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Re: 400km + Link

Wed May 07, 2008 11:21 pm

760-780mhz is used for UHF tv, or atleast, reserved for. I think we would get our asses handed to us if we started using that gear lol
 
WirelessRudy
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Re: 400km + Link

Sat May 10, 2008 1:29 am

If you want to play, consider this:

Use long wave radio. Long wave radio travels around the earth. You only need very long antenna's and/or high power.
Or medium radio frequencies (marine) can be used for ´bouncing´ around the earth. I can't remember the exact frequencies but in Shipping and amateur band 400 km is only medium distance.
I can remember some frequencies could only reach certain distances at certain times of the day. This is because the reflective layer around the earth varies in distance to earth surface depending on day or night (sun's energy).
Morse or later TOS (Telex over Radio) traveled around the world, and the data was analogue, although it looked a bit like the digital form we use today. (Morse was long and short beeps, like 0 and 1 in digital. TOS used even bits if I remember well)

So, find a free (amateur) radio wave as carrier for the digital data to be transport. I don´t know how, but can imagine it is possible. I know amateur radio users can transport digital data around the world. Speeds? Haven´t a clue, very low I presume.

May be here the new 801.xxx´n´ technologies could be used to use multi path for different bounces of the radio signals.
This way even ancient radio techniques could transport digital info much faster. I´m not an technician, more a fantast maybe!

Good luck!

Rudy

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