Following on from the "WIFI Extended coverage".......

[GymRatZ]

Having read with interest the high-gain (though illegal) parabolic network sharing kind of thing I got to thinking.

As there are plenty of knowledgeable types re: Microwave comms etc I thought about the viabillity(sp) of a homeshop link.

Might be flogging a dead horse but, here goes....

House is 80m ASL very close to the top of Hill but on the blind side so no line of sight. The hill rises to 110m within about 500m then drops off over the next couple of miles, with un-interupted path to shop. Shop is 3 storey with posibillity of farly tall mast on top so clear view to non-house side of hill.

Distance point to point is 8.5km

so... simple yes or no question....

With a high gain parabolic dish at each end on as much height as I can get, would the hill/houses obscuring Line Of Sight for a fairly short distance attenuate the signal too much to make the "experiment" even worth considering?

I appreciate the practice would fall well outside of the law, but even a

10Mb connection to the works network which has a 4MB cable hook-up would be a cracking utillitiy for the home office. :¬))

other alternative is 1Mb DSL at home connecting via VNC but limited to

348 Mb upstream from office.

Cheers Pete

[Ian Stirling]

With megawatts of power, maybe, otherwise basically not.

I suppose there is no possibility of a mast to give you LOS to top of hill, a box on the crest? Power to the box would be nice, but solar could be made to work.

[tony sayer]

In article , GymRatZ writes

From what you say this looks like a no hoper. If you can't see it then it ain't gonna go. If you are looking towards a hill that is some 110 and you are at 80 then even assuming that you add in your house, another

10 say that means you need an extra 20 metres above that to even see over the hill. At the distance your describing unless you go up some hundreds of metres at the shop end, this isn't going to fly!....

[GymRatZ]

It's already occupied by Portishead police "village" and a big comms tower. Don't think they'd give me mast space for a domestic illegal LAN extension.

:¬(

I did consider sighting up a suitablly positioned large building in S.Wales and reflecting the signal as both sites have a clear view across the River Severn.

I think it's just going to have to be VPN and a slow as old chips DSL connection. But that's missing the spirit of adventure. :¬)

Cheers.

Pete

[Mike]

Do you own the top of the hill ? If so it is possible to build a passive reflector that can send the signal down the other side, though how you go about designing one I don't know I'm afraid.

[Gordon Henderson]

The parabolic dishes, yagis, etc. aren't neccessarily illegal. The ones we I've used in the past certianly aren't.

The coms tower is unlikely to be owned by the police - look at the base if you can. A lot of them are owned by NTL, Crown Castle or Western Power (in the SW)

However, the price rises exponentially the higher you go - start at 4K pa for 10m off the ground...

Indeed.

You get problems with wave bounce in the fresnel zone.

Yes, but it does work... If you are going down this route, get the same make of router at each end... In theory, VPN protocolls are "standard" but I've had problems with one vendors interpretation of standards vs. another.

I've used Draytak Vigor routers to build multi-site VPNs recently with good results, but that aren't the cheapest. Some units do have phone sockets though, and although I haven't used them, I have a friend who has setup a set of small offices using them and he says it's works great and saves their phone bills...

Gordon

[The Natural Philosopher]

You may need special kit, and it gets expensive.

If you arer on the same exchange, get a copper circuit from BT and stick your own DSL kit on each end. This is the cheapest way to move about

1-2mBPS around a single telehopone exchange area.

Otherwise use ADSL and VPN.

I've done a bot of microwaving - its not cost effective really.

If you are in e.g. NTL cable areas, they may do you a nifty fiber limk.

[The Natural Philosopher]

They will rent you mast space for anything legal, but the cost is about

5 grand a year with rack space and power, plus they will charge you per antenna to install irt all.

Indeed.

[The Natural Philosopher]

Another thougfht. BT has a 'virtual ethernet' product that runs at around 8-Mbps, using latest DSL type technology.

[Ian Stirling]

The angle needs to be right of the building too, and the building needs to be reasonably (+-5cm) flat over large portions of its surface.

Can you get LOS to the top of the tower? Idly wondering. Big dish pointing at top of tower on either side. Hmm. If a router does omnidirectional to 100m, then for 8Km you need 80 times the range, or 640 times the directivity. This means you're looking at an antenna on the 8Km link of about 1/40th of a steradian, call it 1/7 of a radian. So, you need a dish of around 12cm*7 = 74cm, if you got an omni antenna router up the tower. Or with a 1.8m dish, the signal would be 5 times stronger than needed.

Now, if you're 500m from the tower, and want to hit it and put all the beam in a 5m diameter (assuming the tower has a 1m radius), you're looking at a dish of ... Hmm. I make it 12m. I think they might notice that.

You don't even need an active repeater - a couple of 60cm dishes wired back to back pointing in the right directions would make this so much easier.

Any nearby properties that might cut the corner for you, and also want a broadband link?

[John Rumm]

You need LOS or a cable (a single length go CAT5 can be 300m remember). You could possibly get LOS in more than one step...

As long as you are not tweaking up the power of the output stages you should be legal, high gain yagis etc. are only focussing the available power more accurately.

ISTR Bob Cringly describing a setup he built like this to get over a hill on a 20km trip to reach DSL. See if you can find it in the archive here:

other alternative is 1Mb DSL at home connecting via VNC but limited to

or several aggregated ones....