Jim - Since you've had some experience using 5.8 GHz h/w - what do you think of these "upconverters" that are being sold - 2.4 802.11b goes in, and they mix it with an LO up to 5.8G and amplify it in one box, then downconvert on the other end. (this is for long haul backbone, not the original poster's community network install). Their advertising claim is to get you out of the 2.4G noise by using 5.8, but keep your existing 802.11b hardware, and save money in the end (I've yet to confirm that last part!)
It seems like a neat solution at first (keep your existing 802.11b hardware, just change frequencies, (which they structured to be done at the aplifier insertion point, conveniently enough). Some people will need new antennas if they didn't buy dual band to begin with, but i'm running parabolic dishes with log periodic feedhorns, so either band works fine. Have you had a chance to test these solutions? I've often thought about buying 2 of them and "dropping them in" to the existing backhaul link since the design permits that. The sad part is you don't get the benefit of all that extra spectrum into bandwidth! As you pointed out - the noise floor just keeps going up in the valley here. But there are some real life tricks to getting around that. As far as 802.11a - once intel abandoned it for 2.4 G b-g-bluetooth, you may feel it's got a future, but without intel's support, I see it as a bunch of nails in the coffin. Intel pretty much dictates what a motherboard looks like - when they say you'll have 802.11b and bluetooth, and next year you'll have b+g and bluetooth - they're doing it for a reason - parts commonality. Intel has put alot of research into designing combination b+g+bluetooth single solutions. 802.11a doesn't fit into that system. (Simply put, the 5.8 Ghz components are too pricy for the pc marketplace) Intel's customer satisfaction surveys showed people were satisfied with even the 5.5 Mbps each way for their laptops (reading mail, looking at spreadhseets and power point presentations in conference rooms, etc). The guys who want 50Mbps [and have a business need for it other than the cool factor] are a much smaller population. They'll buy a few 802.11a units, but the sales numbers just don't indicate an adoption trend for 802.11a. I still like 802.11a - and would love to see the price come down on a 1W version on the upper 100Mhz of bandwidth for long distance hauls - but it's just not happening fast enough to handle my growth. There are not enough system manufacturers. Plus china (team xerox) hasn't started coppying it yet. With regard to the 6 dbi ant. gain for 1000 mw - you must also take into account cable losses at 2.4 G when engineering the solution. That's why systems are engineered from components and not snapped together as amps and antenna combinations. (although some companies snap together amps, antennas and cables, but I prefer to use heliax instead of LMR400) Also while the FCC does limit transmit system gain, they do not place _any_ limit on receive antenna gain. You can use a 12' satellite dish if you want to, and run it into the 2nd port. Many cards allow you to route TX out one port and RX in the other. Place the two antennas on a colinear axis, and poof - you have increased the link budget while complying with ALL FCC rules. At the same time, you've narrowed your field of view to only a fraction of a degree (-3dB beamwidth) which cuts down the clutter of the valley floor. You can also leave out the receive preamp and its noise floor. 3 problems solved. and 802.11b lives on with link margin to spare. (If the FCC didn't make such lousy rules, you could run both tx and rx out the same narrow antenna, and not polute so much area with your high power transmitter, and realize gain from the larger antenna - but they don't understand even the simplest concepts like the summation of 4000 poletop transmitters each emitting 1W - sure each one is in compliance, but taken as a system, it eats up the entire 2400-2483 band in a metropolitan area. I cheered the day ricochet died, then yanked down all their transmitters left on top of the RF sites I managed and ran over them with my truck since they didn't come get them per their contract requirements.) Necessity is the mother of invention. Some people are just more creative with their solutions! Everett -- general wireless list, a bawug thing <http://www.bawug.org/> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless
