Thanks, i'm glad someone has tried this before we did. I think I've underestimated path loss over water. My previous calculations came up with just over 120dB of free space loss.
The problem is we're working on a tight budget (this is a personal project after all, something to keep me occupied during the weekends). Which is why we have to really build our equipment from scratch. Any ideas? RF amplifiers are dreadfully hard to build, and so are parabolic antennas. I did do some research on large patch antenna arrays but got inconclusive figures. > -----Original Message----- > From: Orlando Andico [mailto:[EMAIL PROTECTED] > Sent: Thursday, May 29, 2003 2:20 PM > To: '[EMAIL PROTECTED]' > Subject: RE: [plug] OT: Cheap 802.11b AP's > > > On Thu, 29 May 2003, Chaves, Jan Amcil wrote: > .. > > A friend and I are coming up with specs for a really long > 802.11b link (some > > 20km, maybe more, over open ocean). The idea is to > minimize transmission > > You cannot do that with cheap AP's due to the low receive > sensitivity. For > example Linksys AP's only have -80dBm sensitivity at the > receiver @ 1Mbps. > > Contrast this with -91dBm for the Aironet 340 and -94dBm for > the Aironet > 350 (both by Cisco). > > We have a 10km overwater link between Cebu and Mactan. As you > well know, > path loss overwater is tremendous. We could only get 2Mbps > over that link > using Cisco 21dBi solid parabolics. Adding an amplifier to one end > (increased transmit power to 500mW and receive gain by 12dB) > increased > speed to 5.5Mbps. > > So for a 20km link overwater, forget about cheap AP's. Use > the best ones > you can get. And, on top of that, get yourself some > amplifiers. We use > antennas and amplifiers from Hyperlink > (www.hyperlinktech.com) -- Cisco > antennas cost too much. > > BTW we *do* have NTC licensing for the link I mentioned. > Don't think you > can get away with it unless you are on very good terms with > the local NTC. > > > --- > Orlando Andico <[EMAIL PROTECTED]> > Mosaic Communications, Inc. > > -- > Philippine Linux Users' Group (PLUG) Mailing List > [EMAIL PROTECTED] (#PLUG @ irc.free.net.ph) > Official Website: http://plug.linux.org.ph > Searchable Archives: http://marc.free.net.ph > . > To leave, go to http://lists.q-linux.com/mailman/listinfo/plug > . > Are you a Linux newbie? To join the newbie list, go to > http://lists.q-linux.com/mailman/listinfo/ph-linux-newbie > -- Philippine Linux Users' Group (PLUG) Mailing List [EMAIL PROTECTED] (#PLUG @ irc.free.net.ph) Official Website: http://plug.linux.org.ph Searchable Archives: http://marc.free.net.ph . To leave, go to http://lists.q-linux.com/mailman/listinfo/plug . Are you a Linux newbie? To join the newbie list, go to http://lists.q-linux.com/mailman/listinfo/ph-linux-newbie
