Or the tree is no longer blocking multi-path interference. Jayson Baker wrote: > Multipath interference from the tree. > > On Mon, Oct 26, 2009 at 10:01 PM, John Vogel <jvo...@vogent.net> wrote: > > >> So... I have a customer, been on for a couple of years now. The CPE on >> their home quit working. I go to check it out, log into the CPE from >> their computer, everything looks good, except that a scan for AP's shows >> only the linksys router they have in the house. This is a MT411 with an >> R52 card in it, with a 14dB panel enclosure. I assume the radio card >> quit receiving or a bad pigtail, so I go retrieve the unit from the >> mount, which is about 15 feet AGL (mounted on the facia at the peak of >> the gabled end of the house). I have my bucket truck parked just below >> where the unit was mounted, so I am standing just about straight under >> where the CPE had been when I take it apart to check it out. >> >> First thing I notice when disassembling the unit is that the SMA >> connector was pretty loose, so just for kicks, I tighten it down and >> boot it up. I have my laptop right there at the back of the truck, so I >> am powering it off of the truck and can log into it standing right >> there. I can see the tower my AP's are on, just one lonely tree between >> me and it, about a half mile away and it doesn't have any leaves on it >> anymore (the tower is about 3 miles away). I can sometimes pick up the >> tower directly from my laptop, so this link is a piece of cake, right? >> So after tightening the SMA connector, and booting up the unit, I pick >> it up and point it in the general direction of the tower. It links up. >> -84 to -86 RSSI. So, even though I didn't really think the SMA >> connector being loose had been the problem, it must have been. So I >> re-mount the unit up where it had been. Log into it, and... nothing. >> Scans for AP's show nothing except the linksys. While I am up there, I >> can see about 80% of the water tower the AP's are on, that one lonely, >> straggly, leafless little tree is technically denying me LOS, but, this >> link worked all through the summer just fine, when that one tree had >> leaves on it. But, no AP's showing in the scan. >> >> Maybe I knocked something loose, or there is a problem with the power >> supply coming from the injector inside the house. So I grab my cable >> from the truck, and plug it in (powering the unit off the truck now) and >> try again. Still nothing. So I go back up, get the #...@! thing, and bring >> it back down to take it apart again. While coming back down, about >> halfway down I can see the laptop on the back of the truck, and winbox >> says that the radio (which isn't even pointing at the tower now) is >> associated to the tower. Go back up, and find that if I hold the radio >> at the exact elevation I had it mounted at, a scan won't even SEE the >> AP, much less associate to it. If I raise it about 18 inches, I get an >> -84, same thing with lowering it 18 inches. I get -84 to -86. Moving >> side to side, same thing. At the elevation the mount is at, nothing. >> higher or lower, no problem. >> >> BTW, there are actually 3 120 degree sectors on the tower, and under >> normal circumstances, I can pick up all three of them. Standing on the >> ground, I get two of them. Where the radio had been mounted, nothing. >> >> This isn't a LOS issue, so I start looking for interference. MT reports >> a noise floor of about -98, but I ask the customer if they have any >> wireless stuff they might have added recently. Nothing. There is a >> tractor and stock trailer parked across the yard, below LOS when the >> radio is up on the mount, and impeding LOS if I am standing on the >> ground. The stock trailer has a sheet-metal roof. Could that be >> reflecting signal somewhere? Customer says the stock trailer has been >> there all summer though. I think I remember it being there too. >> >> After spending an hour and a half pulling my hair out, it is starting to >> get dark, so I decide to temporarily set the radio on a tripod on the >> ground so they can have internet overnight and I'll come back tomorrow >> and try to figure this out. Interestingly enough, the best signal I can >> get with the radio on the tripod is when I move it to a point where the >> tractor and stock trailer are completely blocking LOS. I get -83 there. >> -85 when I move it to a point where I can actually see the tower. >> >> Anybody have a link to RF glasses? >> >> John >> >> >> >> -------------------------------------------------------------------------------- >> WISPA Wants You! Join today! >> http://signup.wispa.org/ >> >> -------------------------------------------------------------------------------- >> >> WISPA Wireless List: wireless@wispa.org >> >> Subscribe/Unsubscribe: >> http://lists.wispa.org/mailman/listinfo/wireless >> >> Archives: http://lists.wispa.org/pipermail/wireless/ >> >> > > > -------------------------------------------------------------------------------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > -------------------------------------------------------------------------------- > > WISPA Wireless List: wireless@wispa.org > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ > > ------------------------------------------------------------------------ > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 8.5.423 / Virus Database: 270.14.34/2462 - Release Date: 10/27/09 > 07:38:00 > >
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