N. Thornton says...

Another question concerns spillage of gas: if youre yacking away its
much easier to spill fuel. I cant draw any conclusions but one has to
at least look at these factors.

Considering how many people refuel their cars each year and the
statistics for refueling fires (150 over the last 10 years) I
draw the conclusion that this isn't a significant problem. At
roughly 50,000 traffic fatalities per year, you are in much more
danger driving to and from the gas station.

As far as talking on your cell phone while driving goes, there is this...

|"Simons and Chabris showed participants a film of two basketball
|teams, one wearing black shirts and the other wearing white.
|These displays were created such that all of the actors were
|partially transparent and thus could simultaneously occupy
|the same locations.
|
|The researchers instructed participants to count how many times
|a basketball passed between members of one team, ignoring the
|other team. Just as Neisser had found two decades earlier,
|many participants didn't notice a woman who walked through
|the scene carrying an open umbrella, even though the woman
|was present for several seconds.
|
|Although Neisser's original findings were striking, they
|stimulated little further research - perhaps in part because
|the results were difficult to incorporate into the mainstream
|science of the time, suggests Ron Rensink, PhD, a psychologist
|and computer scientist at the University of British Columbia.
|
|'Back then, there was still a strong belief that we built
|up a visual representation of all the objects around us and
|held it in a big buffer,' Rensink notes. 'Neisser's work
|flew in the face of that -- people didn't quite know what
|to do with it. There seemed to be a general reluctance to
|pursue it.'
|
|Two decades later, Simons and Chabris's replication has
|received a more welcome reception. The team has now extended
|the original findings by showing that inattentional blindness
|also occurs in more natural displays, in which all of the
|actors are fully visible and opaque. Across a range of
|conditions, more than 25 percent of observers missed a fully
|visible and opaque 'umbrella woman.'
|
|In a particularly dramatic demonstration of the inattentional
|blindness effect, half of the observers failed to notice a
|person wearing a gorilla suit who walked into the middle of
|the basketball game, stopped to face the camera, thumped
|its chest and walked off the screen -- spending a total of
|nine seconds on screen."

Source: http://home.att.net/~jeff.dean/blind.htm




--
Guy Macon, Electronics Engineer & Project Manager for hire.
Remember Doc Brown from the _Back to the Future_ movies? Do you
have an "impossible" engineering project that only someone like
Doc Brown can solve? My resume is at http://www.guymacon.com/

Tim Auton tim.auton@uton.[groupSexWithoutTheY] wrote in
:

Jim Thompson wrote:

I was struck by a thought when I heard the latest Palestinian
terrorist trick is to send a kid through the border with a back-pack
bomb triggered by a cell phone....

The Israelis should get a telemarketer's speed dialer and constantly
dial away... boom... boom... boom...

You would have to have every phone in the nation ring every couple of
hours. They're not going to be stupid enough to have the phone both
switched on and connected to the bomb until the last minute.


Tim

Actually,they have to have it active before they enter 'enemy' territory,as
citizens there often notice some stranger fiddling with a package and then
leaving it behind;the common indicator a bomb has been placed.

--
Jim Yanik
jyanik-at-kua.net

On Thu, 18 Mar 2004 00:59:41 -0800, "CW"
wrote:

The countermeasure I think, is fairly simple. Every vulnerable public
place which may be targeted by terrorist bomb attacks, should install
cellphone signal blockers.

Not in the US. Intentional interference is illegal. It likely is in most
places.


Homeland security has done worse on civil liberty laws.

Compared to the cost and unfeliability of security personnel and
person-body checks surely a "cellphone safe" building, train or public
conveyance is acceptable. After all it wasn't that many years ago
(~10) when there were no cellphones. The what did emergency workers
do then? What happend when you are out of cellphone range? Have you
actually heard of anyone dying because the party called couldn't get
his/her cellphone page?

I would certainly feel a lot more comfortable if the building
advertises itself as a cellphone free location to a point where I
would prefer to shop there. A work around for emergency worker
phone access is for the emergency worker to tell a service provider
that he is at a particular cellphone free location. If he needs to be
contacted the service provider will phone that building(s) management
by landline who will then page the emergency worker. It will work
like a 911 line and is meant for emergencies only, not a mom looking
for a shopping mall crazy daughter. Outside these cellphone free
buildings any cellphone will work normally.

the show on discovery channel, mythbusters. debunked that myth,


"John Michael Williams" wrote in message
m...
Claims that people have started fires by using
their cell phone while refueling a car apparently
are false: See
http://www.snopes.com/autos/hazards/gasvapor.asp
and other sites.

However, the first radios transmitted
sparks, so in principle it should be possible to
transmit near a long wire separated by a small gap from
ground or another wire and get a small spark. So, I
decided to try an experiment.

I don't use a cell phone, so I assumed a CB radio
transceiver would be a reasonable substitute: The
power output of a nominal 5 W CB also is consistent
and nonadaptive, so a possible unknown (actual output
power) is avoided. Cell phones are adaptive and
not very consistent in power output, so power
should be monitored during a cell phone experiment.

5 W is considerably more than the 0.2 to 2 W typically
possible from a cell phone; the power should be the
important factor, although maybe someone should repeat this
experiment with a cell phone, which would operate at
a much higher frequency.

I used a Radio Shack TRC-231 handheld (stock #21-1675)
with xmit power on high and set on Channel 40.
The antenna was the one that came with it (about 25 cm
long). I set the volume to max and the squelch at min
to be able to detect anyone else trying to use the
channel; this was just to be sure that my brief, silent
transmissions would not interfere with anyone.

I used the CB indoors, in a mostly metal-shielded
room. Because CB wavelength is around 10 m, everything I
did was in the near field; however, the inverse square law
for power still holds, allowing that the CB antenna is more
of a line than a point source under my conditions below.


The first thing I noticed was that every time I keyed the
transmit button, the CB would switch the
light level of a nearby touch-dimmed lamp, and it
made a Microalert microwave detector scream. I unplugged
the lamp and turned off the Microalert.

Then, I tried to light a 120VAC indicator neon lamp attached
to two solid copper switchback wires totalling about 1 m
long, so the lamp was in the middle effectively of a dipole
antenna. I tested the lamp and found it would light with
10 microamps current. The CB had no effect, even if held
parallel to, and almost touching, the wires. Thus, the near
field of a 5 W CB radio can not supply about 90 V at even
10 uA, under these conditions.

I then attached a 1.2 m monopole antenna to an oscilloscope.
This antenna has a Schottky hot carrier diode and impedance
matching resistors builtin. It's home made, but it's probably
as good as any other wire about that long. I hooked
the antenna coax to an oscilloscope: With the CB transmitting,
and its antenna parallel and 1 m away from the monopole,
the amplitude was about 100 mV p-p, at 27 MHz or so. I could
not get more amplitude no matter how close I held the CB,
or at what angle. Touching the bare monopole wire increased
the amplitude by no more than 10%.

So, first conclusion: To get even a 1 V spark would take a
wire at least 9 m long, all somehow kept within 1 m of the
transmitter. Thus, it appears it is not feasible to create a
hazardous spark with a CB at a gas station.

Just to be sure, I taped a 1 m wire to a table top in the dark
and slowly brought it closer and closer to another wire
plugged into a wall socket 3rd wire ground (yes, I verified
that the socket was wired to ground first!). At each distance, I
briefly keyed the CB. I could not see any spark, even after
dark-adapting my eyes for 10 min and letting the wires touch.
I might have dark-adapted longer, but I don't know whether
I should have been able to see a 50 mV spark or not.

So, I think sliding over on a car seat, and thus generating a
possible static charge, would be more likely to ignite gasoline
vapor than talking on a cell phone while refueling. However, it
would be useful for someone to repeat this kind of test with an
actual cell phone, as opposed to a CB radio. The wires should
be shorter, for one thing . . ..

I'm cross posting to an antenna group, looking for criticism.

John

John Michael Williams

"KLM" wrote in message
...

Compared to the cost and unfeliability of security personnel and
person-body checks surely a "cellphone safe" building, train or public
conveyance is acceptable. After all it wasn't that many years ago
(~10) when there were no cellphones. The what did emergency workers
do then? What happend when you are out of cellphone range? Have you
actually heard of anyone dying because the party called couldn't get
his/her cellphone page?

I'm old enough to remember when doctors would register with security when
they went to a baseball game. There was always at least one announcement
per game - "Dr. 31, call your service."

You can try to ratioanlize it as much as you want. The willfull electronic
interference of a radio service is a crime. Did you read the part of my post
about signal blocking? I thought not. Go back and try again. If a terorist
is going to strike, he is going to strike. The Department of Homeland
Paranoia is not going to be able to do anything about it.


"KLM" wrote in message
...
On Thu, 18 Mar 2004 00:59:41 -0800, "CW"
wrote:

The countermeasure I think, is fairly simple. Every vulnerable public
place which may be targeted by terrorist bomb attacks, should install
cellphone signal blockers.

Not in the US. Intentional interference is illegal. It likely is in most
places.


Homeland security has done worse on civil liberty laws.

Compared to the cost and unfeliability of security personnel and
person-body checks surely a "cellphone safe" building, train or public
conveyance is acceptable. After all it wasn't that many years ago
(~10) when there were no cellphones. The what did emergency workers
do then? What happend when you are out of cellphone range? Have you
actually heard of anyone dying because the party called couldn't get
his/her cellphone page?

I would certainly feel a lot more comfortable if the building
advertises itself as a cellphone free location to a point where I
would prefer to shop there. A work around for emergency worker
phone access is for the emergency worker to tell a service provider
that he is at a particular cellphone free location. If he needs to be
contacted the service provider will phone that building(s) management
by landline who will then page the emergency worker. It will work
like a 911 line and is meant for emergencies only, not a mom looking
for a shopping mall crazy daughter. Outside these cellphone free
buildings any cellphone will work normally.

I read in sci.electronics.design that CW
wrote (in ) about 'Cellphones and
Bombs', on Thu, 18 Mar 2004:
You can try to ratioanlize it as much as you want. The willfull
electronic interference of a radio service is a crime. Did you read the
part of my post about signal blocking? I thought not. Go back and try
again. If a terorist is going to strike, he is going to strike. The
Department of Homeland Paranoia is not going to be able to do anything
about it.

I am ALMOST old enough to remember a similar idea held in UK and Europe
before WW2, that 'the bomber (aircraft) will always get through'. The
RAF pretty well disproved it.

There is a finite probability that an individual terrorist, acting
completely alone, might evade all the checks. But it's far more
difficult for members of a terrorist cell to evade detection.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

Terry Given wrote:

The current situation exists, time doesnt flow
backwards, and if a real solution is not found, the terrorism will not only
continue, but will coninue to get worse. Neither side seems interested in
moving forward though, they are caught up in an ever-escalating round of
murderous tit-for-tat.

OT, but I have to say I fully agree. This will also take away a lot of
the breeding grounds of war-mongering terrorist organizations that seek
islamic/arabic support.

If only...


Thomas

"John Woodgate" wrote in message
...
I read in sci.electronics.design that CW
wrote (in ) about 'Cellphones and
Bombs', on Thu, 18 Mar 2004:
You can try to ratioanlize it as much as you want. The willfull
electronic interference of a radio service is a crime. Did you read the
part of my post about signal blocking? I thought not. Go back and try
again. If a terorist is going to strike, he is going to strike. The
Department of Homeland Paranoia is not going to be able to do anything
about it.

I am ALMOST old enough to remember a similar idea held in UK and Europe
before WW2, that 'the bomber (aircraft) will always get through'. The
RAF pretty well disproved it.

They did not disprove it.
All they disproved is the notion that a war can be won by air power alone.

--
Dirk

The Consensus:-
The political party for the new millennium
http://www.theconsensus.org

On Thu, 18 Mar 2004 13:00:55 -0800, "CW"
wrote:

You can try to ratioanlize it as much as you want. The willfull electronic
interference of a radio service is a crime. Did you read the part of my post
about signal blocking? I thought not. Go back and try again. If a terorist
is going to strike, he is going to strike. The Department of Homeland
Paranoia is not going to be able to do anything about it.



And cellphone signal blocking is localized, short range, same as WiFi.
Put up a sign to that effect in your business premise. Those who feel
they must have their cellphone access 24/7 can always step outside
the door or avoid the place. That business will survive because there
are a miniscule number of 24/7 cellphone freaks.

Anyway the use of cellphones while driving is banned in many states in
the US and worldwide. What is so different in banning their use in
selected public places. The only difference is that signal blocking
is applied universally in that defined building area, and without
having intrusive checks being made on anyone to effect compliance.