| William H. Magill on Tue, 11 Mar 2003 14:22:10 -0500 |
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I'm amazed by the range of your wireless system.
What is your basement like? Carpeting? Finished walls? Is the router below ground level? The building is a brick walled, 1870 structure with wood floors, horse-hair plaster and lath walls. Typical row-house construction of the period. The first floor is 3 steps up in the front, and 12 feet above ground in the rear -- typical sloped ground setup. The basement is accessed from the ground level in the rear. The front of the basement is 7 feet below ground 3 feet above (10 foot ceiling). The basement is mostly "unfinished," that is to say, it's a storage /workshop/ computer room / junk room with the furnace (hydronic heating), oil tank, hot water heater, beer fridge, cat litter, Christmas decoration storage, etc. The Airport Base station is near the rear, so it's more above ground than below (sort of), but still a full 30 some feet below the floor of the third floor (2x12+10) ... 12 foot ceilings on the first and second floors, remember. Being in an apartment, using a wireless router and a PCI card, I find that my signal strength is either highly attenuated or very weak to begin with. I tend to think the problem is caused by having the PCI card's antenna behind the PC and next to a wall, blocking the line-of-sight and the Fresnel zone with metal, furniture, and a wall. My cantenna solves the signal strength problem, partly by raising the antenna to clear obstacles and by focusing the signal. The issues are all RF. Wireless computing is about RF, not data. Do you get ghosts in your TV? but they go away if you move it to a different spot? "Fuzzy" sound on the radio that clears up if you rotate it? Same kinds of issues. It's all about building materials and support beams, antenna orientation and propagation patterns - RF "bounces," is absorbed, etc. Are you new construction? They did away with wood in partition walls about 10-15 years ago and now use metal studs to hang the dry-wall on! Do you live in a high-rise ... those big square/round columns in the corners tend to be "hiding" the Steel Risers used in the construction... Got a concrete floor (mine are wood)... bet-cha that it doubles as a pretty good Faraday screen. Technically, re-bar used in the construction of the poured concrete floor is bonded together and grounded -- usually to those steel risers, which are in-turn grounded. Cinderblock (even hollow block) or brick walls eat up the low-power RF signal emitted under FCC's part 15 (the reason you don't need a license for an 802.11 transmitter). ... I forgot to mention, the reason I get reception in the back yard is because the BaseStation is positioned "in front of a window." This means that if I can see the base station from the backyard I can use it 40-50 feet away (or more, I haven't tried.) But since the yard is "L" shaped (what in row-house terminology is called an "outside hallway"), and the BaseStation is at the top of the "L," and since a brick wall covers the bottom of the "L" and the length of it , there is a large "blind spot." Again, it's a simple RF propagation issue. Apartment buildings also suffer much more from RF interference from other non WiFI devices in the same band -- "microwave" ovens and cordless phones are the two most common -- not necessarily yours, but your neighbors. Most of my coordless phones are now 9mhz phones. (With a 12 room house on 4 floors, I've got some kind of phone in each room.) I also use channel 8, to avoid the "everybody defaults to 1" problem. T.T.F.N. William H. Magill # Beige G3 - Rev A motherboard - 768 Meg # Flat-panel iMac (2.1) 800MHz - Super Drive - 768 Meg # PWS433a [Alpha 21164 Rev 7.2 (EV56)- 64 Meg]- Tru64 5.1a magill@mcgillsociety.org magill@acm.org magill@mac.com _________________________________________________________________________ Philadelphia Linux Users Group -- http://www.phillylinux.org Announcements - http://lists.netisland.net/mailman/listinfo/plug-announce General Discussion -- http://lists.netisland.net/mailman/listinfo/plug
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