The Cringely passive repeater path he (badly) describes here does not work. It mathamaticly cannot get a signal above -90dBm. In fact it comes out much lower.
As an example... If we had a 24 dBi antenna on both ends of a point-to-point link with the legal max power of .25 Watts (FCC 15.247) we would have a fade margin of 47.775 dB (with a 80 dBm RX threshold) over a 1 mile link. If we had a passive repeater connecting two 1 mile links we would have to multiply the pass loss of one link (104.2 dB) by 2 and the antenna gain (48 dBi) by 2. This would have a total path loss of 108.4 dB and would put the RX signal at -88.42 dBm. 8 dB below the -80 dBm needed for most cards. With this equipment, you really could only do about 1/2 mile on each link before you barely got above the RX threshold. Of course this is ignoring transmission line or connector loss/attenuation or any atmospherics. Passive repeaters have the disadvantage of having path loss on both paths that you need to make up with a really hot signal or amplification in the middle. Tim On Wed, May 29, 2002 at 10:21:29AM -0700, [EMAIL PROTECTED] wrote: > or you could stick a few pringles cans on his roof to act as passive > repeaters... > http://www.pbs.org/cringely/pulpit/pulpit20020207.html > -skip > > > On Wednesday, May 29, 2002, at 06:37 AM, w v.d.Bosch wrote: > > > Hi all, > > > > I'm relatively new to the wi-fi scene, so if my question sounds stupid, > > I apoligise.... > > > > I have a cable-modem at home, but a friend of mine who lives just a > > couple of houses away, can't get it due to bad-cabling and stuff... So > > we set out to establish a wireless link between his and my house but > > there are some obstructions in the way; > > > > a brick house.... > > > > The signal is sometimes able to penetrate this building but the > > link-quality is always 0. Do you guys think if I use a Yagi antenna on > > both ends I will be able to get a stable link?? How many wavelengths > > should this yagi be? Or is it just impossible to penetrate a brick > > house with 802.11b ?? > > > > Both the AP and client-card are transmitting at 100mw (used to be 30, > > but that increase in power didn't seem to improve the signal) > > > > Thanx in advance, > > Grtzz from Wilbert > > (the Netherlands) > > > > -- > > general wireless list, a bawug thing <http://www.bawug.org/> > > [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless > > -- > general wireless list, a bawug thing <http://www.bawug.org/> > [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless -- Snail: Tim Pozar / LNS / 1978 45th Ave / San Francisco CA 94116 / USA POTS: +1 415 665 3790 Radio: KC6GNJ / KAE6247 "It's a damn poor mind that can only think of one way to spell a word." - Andrew Jackson "What is wanted is not the will to believe, but the will to find out, which is the exact opposite." - Bertrand Russell, "Skeptical_Essays" -- general wireless list, a bawug thing <http://www.bawug.org/> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless
