For F in MHz and D in miles, free space path loss = 36.6 + 20 * log(D) + 20 * log(F)
for 2.4GHz and 10 miles, the free space path loss is 124dB. lets assume a 23dBm transmitter, -89dBm rx sensitivity @ 11Mbps and FER of 0.08, and 24dBi of gain at each end of the link. 23dBm + 24dBi + 24dBi + 89dBm = 160dBm of available link budget, less the 124dB of "free space" path loss, less the "about 30dBm of attenuation", and you're at 6dB of link margin, before you count other losses (connectors, coax, antenna pointing errors, etc, etc.) Those 200mW cards only have a -92 or -93 dBm rx sensitivity @ 1Mbps, so you're at perhaps 10dB of link margin before losses. If you established a link in these conditions, it couldn't have been solid, and there is no way you had "plenty of signal left over to make a link with a reasonable fade margin". Perhaps your 2 miles of trees/urban clutter/housing had < 30dB of attenuation? Jim Casey Halverson writes: > "NLOS" (i really hate that acronym) can be done with 802.11b gear, but its mainly a > hit or miss. > > For example, I had about a 10 mile path, 2 miles of which were solid tree/urban > clutter/housing/etc. all of that garbage caused about 30dB of attenuation, but I > had plenty of signal left over to make a link with a reasonable fade margin. This > is a story of a link that probably shouldnt have even worked that did. > > Next example, on a 2 mile shot, i cannot get through 30-50 feet of my apt with 24dBi > parabolics and 200mW radios. Here is a sad story of not being able to make it > through obstructions, no matter how little or insignificant i thought they were. > > It all depends on the materials in the path. Since we do not all possess magical > powers to determine path content, its hit and miss. > > We could paper link this path to death, or you could find someone with some gear and > try it yourself. Two 24dBi parabolics and a pair of 200mW radios are your best shot > if you want to use 802.11b. > > > > -----Original Message----- > From: George [mailto:[EMAIL PROTECTED] > Sent: Thursday, July 24, 2003 11:16 AM > To: 802.11B NEWS GROUP > Subject: [BAWUG] 802.11b Long Range non line of sight > Importance: High > > > Hi guys, > > I was wondering if anyone had came across with an 802.11b equipment that doesnt > need clear line of sight. > I am tasked of bridging a link for a10mile remote site. But Line Of sight is > not very clear. Can anyone please > suggest what can i possibly do to accomplish this. > > thanks in advance > > George > -- > general wireless list, a bawug thing <http://www.bawug.org/> > [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless > -- "Speed, it seems to me, provides the one genuinely modern pleasure." -- Aldous Huxley (1894 - 1963) -- general wireless list, a bawug thing <http://www.bawug.org/> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless
