LOS required for short 802.11b link?

Gerry

Hi, I would be very grateful for any info on this. Basically I want to set up a link between 2 houses, they are under a kilometre apart ( perhaps 750 metres ). The problem is I may not have permission to put an aerial on the roof of one of the houses. So is there a way to get a signal say with a high powered antenna out the window, which may not have LOS to the other house? The other house can have a good rooftop antenna if necessary.

Magic Monkey

Hi Gerry,

LOS is important. You could put a flat panel aerial on a swivel-bracket on the wall facing the other house, and that should work. Best if you can get the card/cable/aerial to be as powerful as possible, say close to 20dBi.

You may have to move the Pc to a room with a window, that's facing the other house, or put the aerial on another side of the wall, face it towards the other house, and just lead the Coaxial cable into the window, or drill thru the wall.

As an aside, we've an omni up at ~20dBi, and can get the signal in a 1Km radius, just holding a flat panel (14dBi) aerial up overhead, testing with an iPaq. It should be cool.

P.S You in Maynooth BTW?

Gerry

Yeah basically I'm moving to maynooth next year, and want to connect 2 houses. Had a good look today, LOS may actually be possible, but its going to be a bitch to get an aerial up on the roof of the apartments. Failing that, is there any chance of getting connected to Peanut who is in celbridge? He was doubtful about it before I think.

Presumably when you are holding this flat panel up, it has good LOS to the omni?

Magic Monkey

Originally posted by Gerry
Yeah basically I'm moving to maynooth next year, and want to connect 2 houses. Had a good look today, LOS may actually be possible, but its going to be a bitch to get an aerial up on the roof of the apartments.

You might'nt need to get on the roof, maybe out the window on the second floor.

Failing that, is there any chance of getting connected to Peanut who is in celbridge? He was doubtful about it before I think.

I'm Peanuts brother - If there was an intermediary link somewhere in Celbridge, on the Maynooth road then it's possible. Other than that, it would be highly unlikely to get a direct connection to us.

Presumably when you are holding this flat panel up, it has good LOS to the omni?

Yep, pretty good. Although, some objects do block the signal (building, trees), so more height the better. Should be ok out the window of the apartment (is it on the second floor?).
I forget the SNR results, but you can definitely establish a link. Obviously, with a more powerful aerial, the better the link.

Gerry

its on the second from top floor, can't remember if that makes it the second or third from the bottom. That would barely be enough to get over the first line of trees, but we shall see.

NeverSayDie

Yeah, it's only 20-30ft above ground level. Dodgy, but given the short distance a decent antenna might be able to make it.

Anyone know what the story is with reflections/bouncing? I've heard you can sometimes use that to get a signal even without LOS. There's quite a few big buildings around the target building, so if the absorbtion wasn't too bad, maybe we could get a reflected signal?

topgold

We bounced an 802.11b signal out of a ground floor room, up four stories to another base station, then down the length of a 155m car park by using a directional antenna. We were trying to send the signal into a plate glass window at street level. But a large granite building next to the car park bounced our signal around and actually caused it to turn 90 degrees to itself. So if you've got polished granite facades along your line of sight, you could have an interesting time.

We're in the lobby of the Ormonde Hotel during the Kilkenny Arts Festival with the hotspot we set up from 11-18 August if you're interested in seeing our kit.