And the message said "200mW"..
Greg DesBrisay writes:
>
> Oops! I responded too quickly to this message!
> You were responding to Casey Halverson's posting, not mine.
>
> Apologies,
>
> Greg
>
>
> On Fri, 2003-07-25 at 08:40, Greg DesBrisay wrote:
> >
> >
> > Jim,
> >
> > I specifically said this was a non-802.11a system.
> > The power was higher than 200 mW.
> >
> > Greg
> >
> >
> >
> > On Fri, 2003-07-25 at 00:14, Jim Thompson wrote:
> > >
> > > 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
> > > > --
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> > > >
> > >
> > > --
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> > > -- Aldous Huxley (1894 - 1963)
> > >
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> >
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>
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