Hello Jim, Tell that to the guys in Greece that managed to get links happening between the canary islands :)
I've heard 130km from a consume guy that gave a talk out here a month ago, and I saw an announcement for 70km a few months before that... 15dBm cards and 24dBi dishes... (no amps) I know for sure 10km is more then possible, and at 11Mbits, using a 180 8 slot slotted wave guide and a cantenna... across the bay here, across at least 1 runway at Sydney airport and there is also something in the vicinity of 120 access points located at Sydney airport... I found horizontal polarisation to be a lot more effective then vertical also... -- Best regards, evilbunny mailto:[EMAIL PROTECTED] http://www.cacert.org - Free Security Certificates http://www.nodedb.com - Think globally, network locally http://www.sydneywireless.com - Telecommunications Freedom Thursday, December 12, 2002, 7:52:58 AM, you wrote: JA> Concur with Tim's experience and the issues with doing this. JA> Additionally, Sprint Broadband Wireless engineers told me they have similar JA> difficulties trans-Bay from San Bruno (near Sign Hill) to Berkeley, JA> Oakland, etc. - visual line-of-site but several 'environmental' factors JA> involved - Bay Bridge, the Bay (waves are highly variable reflectors), the JA> distance and the marine layer. JA> Get two hams, two sets of 2.4 GHz gear with signal strength indications, JA> coordinate antenna alignment live. What we need is a good 100-500mW CW JA> beacon transmitter and a complimentary receiver with signal strength and JA> Sinad readouts as a test set...hmmmm.... JA> SF-Berkeley is the toughest shot, over water with the Bay Bridge clutter, JA> etc. - the rest would be easier from hilltop levels, but from ground or JA> even building top level - ooooooohhhh - tough call. JA> Stretching a 300 meter technology at these power level out to 10-30 km is JA> asking a bit much no matter which antenna, etc. you're using. JA> At 12:00 PM 12/11/2002, you wrote: >> 1. Re: Cross-Bay link (Tim Pozar) >> >>Message: 1 >>Date: Tue, 10 Dec 2002 11:59:57 -0800 >>From: Tim Pozar <[EMAIL PROTECTED]> >>To: "Robert R. Ballecer, SJ" <[EMAIL PROTECTED]> >>Cc: [EMAIL PROTECTED] >>Subject: Re: [BAWUG] Cross-Bay link >> >>On Sat, Dec 07, 2002 at 06:30:56PM -0800, Robert R. Ballecer, SJ wrote: >> > Has anybody had experience with shooting 802.11b across the bay? >> I ask >> > because my organization has properties Fremont, Berkeley, San Jose, Santa >> > Clara (University), Los Gatos, Los Altos and San Francisco. Each location >> > is high enough to be able to "see" at least two of the other sites >> through a >> > telescope. There are not many practical uses for the link at the moment >> > (each site already has broadband access) but it might be a nice project for >> > my free time. >> > >> > I was thinking about getting a few of those Senao 200mw cards and >> use them >> > in conjunction with some homebrew antennas. Anybody have the equations I >> > need to figure out how the distance will affect S/N? What says the FCC >> about >> > 200mw cards? >> >>We tried one 20 mile link with 250mW amplifiers from Sign Hill in >>South San Francisco to a house in Hayward. The antennas were 24dBi >>dishes. We were able to get both ends to associate and get some >>data back and forth, but not consistently. You can see the path >>profile at: >> >> http://www.lns.com/projects/sunsetwireless/paths/Matt2SignHill.pdf >> >>Some of the problems we ran into was antenna alignment. 802.11 >>radios do not update C/N data fast enough and the data tends to >>bounce around. We decided that in order to line up paths you really >>need to use different transmission gear for antenna alignment such >>as a carrier wave at the frequency you want and a spectrum analyzer. >>This also helps as you really have a hard time tracking SS signals >>on a spectrum analyzer. >> >>Of course there are a number of things you need to look at before >>you get to this point. Looking through a telescope will pass some >>some tests but you need to look at other things like "refraction" >>and "fresnel zones" to insure that the data will get from one >>transmitter to the other. I think there has been some discussion >>on the list before in "engineering" paths. If not, I can put >>together one. >> >>Tim JA> -- JA> general wireless list, a bawug thing <http://www.bawug.org/> JA> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless
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