Subject: (Huuva) Re (Itzikowitz) wireless computer network (fwd)
Date: Tue, 30 Mar 1999 083915 -0600 (CST)
From: "Roy L. Beavers" <rbeavers@llion.org>
To: emfguru <rbeavers@llion.org>
--------------------------------------------------
---------- Forwarded message ----------
Date: Tue, 30 Mar 1999 16:30:15 +0200
From: Adam Huuva
To: "Roy L. Beavers"
Subject: Re: (Itzikowitz) wireless computer network (fwd)
As it happens, I wrote something on this for a school project a while
ago. Strictly layman stuff though, I'm NOT an expert. I welcome the
experts on our list to comment on the stuff i wrote, should they bother.
I should have revised this by now; there are most certainly errors in
this text. I also had a strong bias towards the wireless-is-bad
direction in the text. But it is understandable because all wireless
applications were considered safe at the time. The few (including me)
who thought otherwise weren't taken too seriously. Looking at it now and
remembering the way things were just two years ago, I must say that the
general view on EMFs has changed quite a bit even in this time.
The project is on the net, here:
http://www.cdt.luth.se/~di-net/WaveLAN_Project/Pages/wl_11.html
Project base over here: http://www.cdt.luth.se/~di-net/WaveLAN_Project/
And for those without a browser handy, here is the text:
WaveLAN and your health
WaveLAN
The WaveLAN wireless local area network transmits at 2.4 GHz. This is
the same frequency as microwave ovens. Microwave ovens heat up the
water in food. The human body consists of 80% water. This fact certainly
makes one interested in the potential health hazards implied by wireless
LANs.
WaveLAN's own public WaveLAN Bulletin version 9/94 assures the reader
that the WaveLAN system is completely safe and that it complies
with the standards and recommendations set by NCRP Scientific Committee
53, IEEE Standards Co-ordinating Committee 28, IRPA/INIRC
and NRPB.
However, voices have been heard that the standards and recommendations
aren't what they ought to be. The standards and recommendations
are said to only look at the heat absorbing problem and mean levels.
WaveLAN, like other radio devices, emits radio frequency electromagnetic
energy. According to the creators of the WaveLAN system, Lucent
Technologies, extensive research on the safety of exposure to radio
frequency electromagnetic energy has been carried out for more than 4
decades. This research is said to be continually reviewed and
interpreted by committees of scientists who develop safe limits for
exposure.
Furthermore, only one transmitter is said to be active at any point in
time, so the radiated power of a total network even when it has 100
nodes
would actually be equivalent to the radiated power of a single
transmitter. WaveLAN transmitters operate at a powers from 0.1 (100
milliwatts)
watts to 0.6 (600 milliwatts) watts depending on the specific product in
use and the local regulations. WaveLAN uses a "bursty" type of
transmit/receive protocol, as opposed to connection oriented cellular
phones that transmit and receive constantly.
The WaveLAN bulletin gives an example: If a user would transfer data on
an average of 100 Mbytes per day, the WaveLAN transmitter would
be on the air for approximately 10 minutes. This certainly implies that
wireless networks are not at all as dangerous as cellular phones; an
issue
more and more frequently discussed.
The sceptical say that the LAN-sellers are only talking about mean
output levels. Patrick Lindahl, employee of a large Swedish
telecommunications firm, states: "If you get one snowball in your face
every five minutes it hurts, compared with the same amount of snow
falling
slowly during the same five minutes. It's still the same amount of snow!
You must know what the peak power is during transmission, it's the
transmission peaks that hurt!! 100 Mbytes a day is almost nothing in an
office today! I must be transmitting dozens of Gbytes every day!
(through
optical fibres!)"
The following is stated in the IEEE standard: "No verified reports exist
of injury to human beings who have been exposed to electromagnetic
fields within the limits of frequency and [specific absorption rate]
specified by previous ANSI standards, including ANSI C95.1-1982."
However, no verified reports exist of injury to human beings who have
been exposed to asbestos and X-rays either. Nevertheless, they are
considered dangerous today.
RangeLAN2, a competing product
The RangeLAN2 product uses FHSS technology, which is described
thoroughly above. FHSS technology frequency hopping seems to affect
medical electrical equipment less than DSSS technology. If they also
affect humans less is an open issue.
<"Roy L. Beavers" wrote:
>
> .......Does any one "out there" have some info on this subject?
> I don't recall that the question has come up before????......
>
> Roy Beavers (EMFguru)
> rbeavers@llion.org................
> ...It is better to light a single candle than to curse the darkness...
> .................PEOPLE ARE MORE IMPORTANT THAN PROFITS...............
>
> ---------- Forwarded message ----------
> Date: Tue, 30 Mar 1999 10:58:26 +0300
> From: Yakov itzikowitz
> To: rbeavers@llion.org
> Subject: wireless network
>
> Hi,
> do u have or know any information related to wireless computer networks
> in a schooling environmet?
> Thanks you for your time and attention.
>
> Jacob Itzikowitz
Archive provided courtesy of WaveGuide, http://www.wave-guide.org
Reprinted with permission of Roy Beavers, http://www.feb.se/EMF-L/EMF-L.html