Text 31499, 65 rader
Skriven 2007-04-23 10:25:00 av GORDON HUFF (1:123/140)
     Kommentar till en text av CHARLES SCAGLIONE
Ärende: Re: IBM PC
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-=> TOM WALKER wrote to CHARLES SCAGLIONE <=-

 TW> True. Wireless operates under special rules and has a maximum power
 TW> output limited to 100 Milliwats. Thet fact alone severly restricts the
 TW> range. 

True - we have elaborate rules for radio devices in the US.
However, "range" in a radio system is just that - a system
problem.

100 mW (+20 dBm) is a substantial signal. In addition, 
minimum atmospheric noise occurs near 3 gHz and a
802.11 radio (with "spread-spectrum") has a lot of
"process gain."

You can confirm this on the internet. There is a Utah 
state park with unlicensed 802.11 connectivity over a
17 mile path. There is a Las Vegas wireless convention
that has a range contest ... last time I looked I saw
a 42 mile path claimed 9(from the Las Vegas hotel 
parking lot.) There are wireless ISPs that use 
unlicensed spectrum (same frequency you and I use) 
and get 5-10 mile ranges.

For many years, the microwave ham DX record for 
3.3 gHz was 214 miles. This was done wth 20 mW
and vacuum tubes (but a nice antenna I must admit!)

For that matter, look into the power levels of
1.9 gHz cell phones. In a metropolitan area,
this is -30 to -40 dBm ...sometimes as low as 
-60 dBm (!) (The phones are spec'd for 26 dBm
max -- but is rarely needed.)

The real problem is the 802.11 receivers are deaf.
The 802.11 radios use "Starved Local Oscillators"
to reduce power drain. I understand that a 
"standard" LO improves receiver sensitivity 
10-13 dB (!) This is as much benefit as a good antenna.

 TW> And by the way most of the High Gain antennas, Particualrly Yaga
 TW> and Pringle Can Wave guide types are technical illegal.

Petifogey. *ANY* modification to atype accepted radio is
illegal. I would tell you that changing an antenna on a 
standard connector is permitted by "Part 15."

 TW> But in some lucky cases one can get an occasional good connect.
 TW> Then of course you have the Moral delema of STEALING what soneone else
 TW> is paying for. :-)

Dunno -- many places *give away* internet access. 
Might not be *stealing*.

 CS>Very unlikely someone in an assisted living home would have a wireless
 CS>connection setup to piggy back on.  Not knowing exactly what kind of

The "home" might have one for their staff already. If a few 
clients ask for it, they might do it as an amenity, like
cable TV.

Regards, Gordon
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