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[DPRG] Did you test real distance of RF communication (BlueTooth, Wi-Fi, ZigBee)?

Subject: [DPRG] Did you test real distance of RF communication (BlueTooth, Wi-Fi, ZigBee)?
From: Randy M. Dumse rmd at newmicros.com
Date: Mon Sep 3 17:05:58 CDT 2007

In reinforcement of Tom Brusehaver's post, there is a Fresnel
Zone effect to things encrouching the transmission path.
MaxStream explains it on their site.

I made a reply on c.r.m. which is copied below:

On Sep 3, 5:09 am, RoboHobby <roboho... at gmail.com> wrote: 


> Have you ever done tests in the fields - how long is the
distance for 
> BlueTooh, Wi-Fi, ZigBee, etc.? 


I did rough tests on BlueTooth modules of both Class I and II. I
found 
the short range unit very crisply 10 meters of just less. The
higher 
power one seemed well over 30 meters, even through an
intervening 
concrete wall. 

I have tested the Pro XBee's from MaxStream. They are very much
as 
they describe them. They say up to a mile. We ran a test putting
one 
unit on a car, and the other 1) at chest level, 2) at ground
level. We 
captured the stream from a GPS module, and retransmitted it to a

recording laptop. Then we looked at the stream of data for the 
coordinates which were the farthest away, but with the
transmission 
still in tact. Then we used google earth to plot and thus
measure the 
distance. In the first case, we got a maximum distance of 1.2
miles. 
MaxStream claims up to 1 mile. In the second case we got .49
miles. 


You might want to look at the MaxStream web site. They explain
"the 
fresnel effect" about clearance of antenna from surrounding
objects. 
At 2.4GHz (frequency domain of all the items you listed) you
need 
about 3.5+ meters clearance (at both ends) from anything around
the 
antenna for maximum range. Probably the shorter range results
you 
experienced were due to this antenna placement. 


-- 
Randy M. Dumse 
www.newmicros.com 
Caution: Objects in mirror are more confused than they appear. 



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