In article , David
Buttery  scribeth thus
>furnessvale  wrote in
>news:1400e400-2e40-4965-b72c-9167cd3eb0a4@e10g2000prf.googlegroups.com: 
>
>>> But how would you know? Recently I heard a man on a train ring
>>> someone and spend the first minute so saying that they were on the
>>> train and that it was raining a little bit. Prattle, yes. After that,
>>> he asked how his daughter was doing, and the implication was that she
>>> was quite ill in hospital. Not prattle. I wouldn't have liked to have
>>> cut him off because of that unpromising first minute!
>
>> Sounds like he had decided his priorities for himself.
>
>I think that's unfair. Not so long ago I had to make a phone call about a 
>very serious situation involving someone close to me. I found that a bit of 
>gentle, undemanding chat first was the only way I could settle my mind 
>enough to do the next bit of the talk, which it was extremely important I 
>got right. I reckon I spent longer than a minute on the "prattle" phase.
>

Point is that you can make a call on a mobile in a normal voiced
discreet manner, but there are a LOT who can't and have to shout think
their sooo bloody important!....
-- 
Tony Sayer

Alasdair  wrote:

> On Tue, 4 Dec 2007 14:44:03 +0000 (UTC), Mike Civil
>  wrote:
> 
> >I suspect the devices are pretty indiscriminate. After all they're
> >unregulated and presumably designed to be multi-frequency so that they
> >can affect any mobile phone in any country regardless of what frequency
> >band(s) they happen to be using.

> I wonder what the penalty is if one is found using one of those
> jammers?

How stupidly would you have to use it to get caught?

You're in a moving train, switching it on for a second or two at a
time, and the prattlers just think it's a network problem when they
get cut off. There's no way the "authorities" would pin it down.

"Nomen Nescio"  wrote in message 
news:c01cb116262e514280f35c7563d0085e@dizum.com...
.
>
>> I wonder what the penalty is if one is found using one of those
>> jammers?
>
> How stupidly would you have to use it to get caught?
>
> You're in a moving train, switching it on for a second or two at a
> time, and the prattlers just think it's a network problem when they
> get cut off. There's no way the "authorities" would pin it down.
>

Can anyone advise whether these devices are legal to possess? I know they 
are illegal to use but am unsure about possession.

From what I understand the range of these devices is rather limited - only 
around a radius of 5 metres or so, and are not always reliable against some 
phones/networks. You'd need one of the more powerful mains powered ones to 
silence an entire train carriage I would have thought.

The tempation to use these devices to silence the inane babblers on the 
train or bus is rather strong I admit. I notice with horror that they are 
looking at introducing the use of mobile phones on aircraft - Sheesh!

-- 
Peter <X-Files fan>

On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
 wrote:

> I notice with horror that they are 
>looking at introducing the use of mobile phones on aircraft - Sheesh!

If this does happen, I imagine the phones will be special ones
supplied by the airline and calls will cost an arm and a leg.  

The argument for prohibiting the use of mobiles in aircraft has always
been that the radio transmissions could affect the electronics of the
aircraft and could be dangerous.  Are they now saying that we have
been conned all along and mobiles are quite safe if used in flight.

-- 
Alasdair.

On Sat, 08 Dec 2007 02:19:41 +0000, Alasdair 
wrote:

>On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
> wrote:
>
>> I notice with horror that they are 
>>looking at introducing the use of mobile phones on aircraft - Sheesh!
>
>If this does happen, I imagine the phones will be special ones
>supplied by the airline and calls will cost an arm and a leg.  

They've already got those.

>The argument for prohibiting the use of mobiles in aircraft has always
>been that the radio transmissions could affect the electronics of the
>aircraft and could be dangerous.  Are they now saying that we have
>been conned all along and mobiles are quite safe if used in flight.

Christopher A.Lee wrote:

>> The argument for prohibiting the use of mobiles in aircraft has always
>> been that the radio transmissions could affect the electronics of the
>> aircraft and could be dangerous.  Are they now saying that we have
>> been conned all along and mobiles are quite safe if used in flight.

The plan involves a very low powered base station actually inside the 
aircraft, linked to a satellite channel to allow calls while in flight. 
There will, naturally, be a premium rate charged for calls. This will be 
turned on when the plane is at cruising height, & turned off when landing.

The problem has been that cellphones don't work inside aircraft without 
cranking the transmit power up all the way, which can potentially 
interfere with the signals used for glidepath control while landing, as 
well as GPS signals, especially when you have a couple of hundred phones 
all shouting as loud as they can to find a cell to use. They also stop 
working on flights over water once you get more than a few miles from 
land. Another problem is that they can't lock onto the channel if 
they're moving at more than about 300 mph relative to the base station 
due to the doppler effect.

The proposed system means that the transmit power on the phones will be 
minimal & under the control of the aircrew. They could also potentially 
transmit a "System not working" signal to stop phones from transmitting 
at dangerous points of the flight.

-- 
Tciao for Now!

John.

In message 
          Alasdair  wrote:

> On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
>  wrote:
> 
> > I notice with horror that they are 
> >looking at introducing the use of mobile phones on aircraft - Sheesh!
> 
> If this does happen, I imagine the phones will be special ones
> supplied by the airline and calls will cost an arm and a leg.  

They've existed for some years now, and yes they do cost an arm and a leg.

> 
> The argument for prohibiting the use of mobiles in aircraft has always
> been that the radio transmissions could affect the electronics of the
> aircraft and could be dangerous.  Are they now saying that we have
> been conned all along and mobiles are quite safe if used in flight.
> 

The ones fitted are properly screened.

-- 
Graeme Wall
This address is not read, substitute trains for rail.
Transport Miscellany at <http://www.greywall.demon.co.uk/rail/index.html>

On Sat, 08 Dec 2007 02:19:41 +0000, Alasdair 
wrote:


>The argument for prohibiting the use of mobiles in aircraft has always
>been that the radio transmissions could affect the electronics of the
>aircraft and could be dangerous.  Are they now saying that we have
>been conned all along and mobiles are quite safe if used in flight.

you always have been - never a single instance of petrol stations
exploding or planes crashing due to mobile use. 

True they do produce interference but it is only significant (even
then tiny) at close range. I would suggest that the audio interference
from their use by owners is more of a liability - there are loads of
instances of planes being endangered by air-rage.

feebo wrote:

> never a single instance of petrol stations
> exploding or planes crashing due to mobile use.

However, they can cause havoc in hospitals. I was talking to a
rheumatologist who said that the mobiles interfere with quite a wide
range of medical equipment, and she demonstrated it for me with one of
those doppler scanners that measures blood flow.
-- 
http://gallery120232.fotopic.net/p9628976.html
(08 609 at Leicester, 3 Sep 1979)

Graeme Wall wrote:

> 
> The ones fitted are properly screened.
> 

I doubt that it was ever really a screening issue, other than a very 
minor risk.

The first problem was that GSM is effectively pulsed, which makes 
EMC much more of a problem.

The second issue is that, when run in a tin can, the handset will 
crank up its power to maximum.

The third issue, again because it is being operated in a tin can, is 
that you can get standing waves set up inside the cabin which 
effective increase to power levels significantly above those 
measured in an open-field site. This can take the localised power 
levels way above those envisaged by the standards.

regards, Ian

In message <4b02gg851j9c.1t6osceq5mt86$.dlg@40tude.net>
          Chris  Tolley  wrote:

> feebo wrote:
> 
> > never a single instance of petrol stations
> > exploding or planes crashing due to mobile use.
> 
> However, they can cause havoc in hospitals. I was talking to a
> rheumatologist who said that the mobiles interfere with quite a wide
> range of medical equipment, and she demonstrated it for me with one of
> those doppler scanners that measures blood flow.

On the other hand I've been in operating theatres[1] where the surgeon has
used a mobile phone during the prodedure.  Also hospitals are quite happy to
rent out roof space for cellphone masts.

[1] Cardiac Catheter labs that are full of high-tech electronic equipment.

-- 
Graeme Wall
This address is not read, substitute trains for rail.
Transport Miscellany at <http://www.greywall.demon.co.uk/rail/index.html>

"Graeme Wall"  wrote in message 
news:ff4ce34d4f%Rail@greywall.demon.co.uk...
> In message 
>          Alasdair  wrote:
>
>> On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
>>  wrote:
>>
>> > I notice with horror that they are
>> >looking at introducing the use of mobile phones on aircraft - 
>> >Sheesh!
>>
>> If this does happen, I imagine the phones will be special ones
>> supplied by the airline and calls will cost an arm and a leg.
>
> They've existed for some years now, and yes they do cost an arm and a 
> leg.
>
>>
>> The argument for prohibiting the use of mobiles in aircraft has 
>> always
>> been that the radio transmissions could affect the electronics of the
>> aircraft and could be dangerous.  Are they now saying that we have
>> been conned all along and mobiles are quite safe if used in flight.
>>
>
> The ones fitted are properly screened.


I assume you mean the aircraft (electronics) has proper screening? Why 
screen a mobile - it is designed to radiate?

Having said that I read recently that mp3 players generate many times 
more RFI than either a mobile phone or a laptop, although I don't own a 
mp3 player so I can't test the validity.


-- 
Woody

harrogate three at ntlworld dot com

tony sayer wrote:

<Cellphones travelling fast>

Another problem is that they can't lock onto the channel if
>> they're moving at more than about 300 mph relative to the base station 
>> due to the doppler effect.
> 
> Not quite true.. If your sideways on to a BST the relative speed will be
> much less;)...
> 
As I said "relative speed" ;-)

I maybe should have said "with a radial velocity relative to the 
transceiving antenna", which would be more accurate.

Another slight problem would be that the radiation from the base station 
antennae is very reduced once you get out of the horizontal plane 
relative to the antenna. There's quite a high gain on the designs 
normally used, giving a much tighter vertical pattern than a standard 
dipole.

> However you will also interfere with a lot of base stations using the
> same channel..

Modern cellphones use channel sharing anyway. IIRC. Either CDMA or TDMA, 
though I can't remember which is used where. The overall network design 
should be tolerant of such errors, though. Things like not re-using the 
same channel set within a biggish group of cells, for instance.

>> The proposed system means that the transmit power on the phones will be 
>> minimal & under the control of the aircrew. They could also potentially 
>> transmit a "System not working" signal to stop phones from transmitting 
>> at dangerous points of the flight.
>>
> Or if it gets too noisy;))

That'll not be the crew deciding that. After all, each person yammering 
is a revenue earner for the carrier :-)

-- 
Tciao for Now!

John.

Woody wrote:

>> The ones fitted are properly screened.
> 
> 
> I assume you mean the aircraft (electronics) has proper screening? Why 
> screen a mobile - it is designed to radiate?
> 
Aircraft electronics is *very* well shielded at the point of origin of 
any potential interference, (Things like ferrite beads on all leads 
passing through the casing, properly bonded joints where metal plates 
join for access plates & so on)& any antennae are shielded from internal 
interference by being on the outside of the metal fuselage, usually as 
far away as possible from interference generation on the manufacturer's 
fitted equipment.

To get the type approval for the phones currently used in aircraft cost 
a fortune, & the test program for the new cellphone units is still in 
progress with a budget of millions of pounds so far. Flight testing 
using a 747 isn't cheap, & separate approval has to be given for every 
individual aircraft design. The new airbus designs are going to be even 
harder to certify, as they use a non-conducting fuselage material.

Non type-approved transmitters, transmitting variable frequencies at 
varying power from random locations in & around the airframe are a 
*very* hard to shield effectively from, & there are limits imposed by 
weight considerations. It's easier & cheaper, not to mention a lot safer 
just to ban them altogether. There are a number of recorded incidents of 
aircraft having to miss a landing & go around, with all the risks & cost 
that involves, due to somebody making a cellphone call while the plane 
was on final approach.

> Having said that I read recently that mp3 players generate many times 
> more RFI than either a mobile phone or a laptop, although I don't own a 
> mp3 player so I can't test the validity.
> 
It would depend enormously on the design. I've got one that's built in 
what amounts to a faraday cage, with a metallic coating on the inside of 
the case, I've got another with no shielding, just the plastic case.

Mobile phones & laptops are more expensive units, so I would think less 
corners are cut during design & manufacture. MP3 players run their 
processor more slowly, so the interference would occur starting lower in 
the spectrum than mobile phones & laptops, with closer spacing of the 
harmonics. On the other side of the problem is the fact that MP3 players 
use the lowest possible power consumption processors available, while 
mobiles & laptops use the circuits that give the best results with 
reasonable power consumption, so there's more power being switched than 
in an MP3 player.

There are tests which they're all supposed to pass regarding RFI 
generation to get approval for sale in various territories, but how many 
of the cheaper units are even tested, or would pass if they were is a 
moot point. The approval mark is very easily reproduced for a casual 
buyer/ non-suspicious customs officer, especially if there is a decent 
quality forged certificate of compliance with the shipment.

I've not got the gear to check properly for myself, but I note that 
neither of the MP3 players or the laptop I'm typing on interfere with 
the FM receiver I'm listening to at the moment, but the GPRS datacard in 
the laptop sometimes does, even when it's just changing cells.

Toss a coin, would you, please. ;-)

-- 
Tciao for Now!

John.

In message 
          tony sayer  wrote:

> In article <64cef54d4f%Rail@greywall.demon.co.uk>, Graeme Wall
>  scribeth thus
> >In message <4b02gg851j9c.1t6osceq5mt86$.dlg@40tude.net>
> >          Chris  Tolley  wrote:
> >
> >> feebo wrote:
> >> 
> >> > never a single instance of petrol stations
> >> > exploding or planes crashing due to mobile use.
> >> 
> >> However, they can cause havoc in hospitals. I was talking to a
> >> rheumatologist who said that the mobiles interfere with quite a wide
> >> range of medical equipment, and she demonstrated it for me with one of
> >> those doppler scanners that measures blood flow.
> > 
> > On the other hand I've been in operating theatres[1] where the surgeon
> > has used a mobile phone during the prodedure.  Also hospitals are quite
> > happy to rent out roof space for cellphone masts.
> 
> Subtle difference there Graeme the panel aerials in use at these sites
> direct the radiated field in a controlled fashion away from the site.
> The intensity is in line with the centre of the aerial and not a lot
> gets directed downwards at the site or upwards for that matter...

But will get directed at the building across the compound...

> 
> Course there will be some reflections around the area but the
> intensities will be much less then a mobile at short rages i.e. in a
> room...
> 
> >
> >[1] Cardiac Catheter labs that are full of high-tech electronic equipment.
> >
> 

-- 
Graeme Wall
This address is not read, substitute trains for rail.
Transport Miscellany at <http://www.greywall.demon.co.uk/rail/index.html>

On Sat, 8 Dec 2007 11:30:39 +0000, tony sayer 
wrote:

>No give them their due the aircraft environment is a very sensitive one
>and is very safety conscious. If there was the slightest risk then they
>should not be allowed but its taken some time to get that far.

Given that just about every flight these days has one or two mobiles
that their owner has forgotten to turn off (I've done it), and that we
haven't heard of any accident relating to one, I think you can be
reasonably sure they aren't a big risk.

Neil

-- 
Neil Williams
Put my first name before the at to reply.

"Neil Williams"  wrote in
message news:475b0e54.633337741@news.individual.net
: : On Sat, 8 Dec 2007 11:30:39 +0000, tony sayer
: :  wrote:
: :
: : : No give them their due the aircraft environment is a
: : : very sensitive one and is very safety conscious. If
: : : there was the slightest risk then they should not be
: : : allowed but its taken some time to get that far.
: :
: : Given that just about every flight these days has one
: : or two mobiles that their owner has forgotten to turn
: : off (I've done it), and that we haven't heard of any
: : accident relating to one, I think you can be reasonably
: : sure they aren't a big risk.

How do you forget to turn it off once the flight crew have told you to do 
so before takeoff..?

Ivor

On Sat, 8 Dec 2007 22:41:01 -0000, "Ivor Jones"
<ivor@despammed.invalid> wrote:

>How do you forget to turn it off once the flight crew have told you to do 
>so before takeoff..?

Because I normally put all my electrical gubbins in the side of my
carry-on bag in order to speed passage through security[1], and
because the seats are so damn narrow it tends to stay there for the
flight rather than going back in my pocket.

Before putting it in said bag, I turn off said electrical gubbins.
However, on one occasion I forgot.  The bag is shoved up in the
overhead by the time the above announcement is made, so a quick check
isn't practical if I'm in a window seat (which is my usual choice), so
I would rely on my turn-off-before-putting-in-bag ritual, which worked
every time but one.

I am by no means the only one who's forgotten, though. My guess is
that at least one on any given 737-sized flight is on.

[1] I'm thinking here specifically of Schiphol, where security is at
the gate, and thus I'm not likely to want or need use of said
electrical gubbins between security and the plane as this is normally
a period of no more than about 5-10 minutes.

Neil

-- 
Neil Williams
Put my first name before the at to reply.

"tony sayer"  wrote in message 
news:410tDyEyLqWHFwT3@bancom.co.uk...
> In article <64cef54d4f%Rail@greywall.demon.co.uk>, Graeme Wall
>  scribeth thus
>>In message <4b02gg851j9c.1t6osceq5mt86$.dlg@40tude.net>
>>          Chris  Tolley  wrote:
>>
>>> feebo wrote:
>>>
>>> > never a single instance of petrol stations
>>> > exploding or planes crashing due to mobile use.
>>>
>>> However, they can cause havoc in hospitals. I was talking to a
>>> rheumatologist who said that the mobiles interfere with quite a wide
>>> range of medical equipment, and she demonstrated it for me with one of
>>> those doppler scanners that measures blood flow.
>>
>>On the other hand I've been in operating theatres[1] where the surgeon has
>>used a mobile phone during the prodedure.  Also hospitals are quite happy 
>>to
>>rent out roof space for cellphone masts.
>
> Subtle difference there Graeme the panel aerials in use at these sites
> direct the radiated field in a controlled fashion away from the site.
> The intensity is in line with the centre of the aerial and not a lot
> gets directed downwards at the site or upwards for that matter...
>
> Course there will be some reflections around the area but the
> intensities will be much less then a mobile at short rages i.e. in a
> room...
>

I'm not so sure about this...I use a wireless cycle computer / heart rate 
monitor.  Part of my normal ride takes me past a mobile mast adjacent to, 
would you believe it, a petrol station.  9 times out of 10, when I cycle by 
the mast, both I and my bike die (i.e. zero heart beat, zero measured speed) 
for about a tenth of a mile.   The mast is set back probably 15 feet from 
the road.

Kevin the Lurker.

On Sat, 08 Dec 2007 11:55:11 +0000, Graeme Wall
 wrote:

>In message <4b02gg851j9c.1t6osceq5mt86$.dlg@40tude.net>
>          Chris  Tolley  wrote:
>
>> feebo wrote:
>> 
>> > never a single instance of petrol stations
>> > exploding or planes crashing due to mobile use.
>> 
>> However, they can cause havoc in hospitals. I was talking to a
>> rheumatologist who said that the mobiles interfere with quite a wide
>> range of medical equipment, and she demonstrated it for me with one of
>> those doppler scanners that measures blood flow.
>
>On the other hand I've been in operating theatres[1] where the surgeon has
>used a mobile phone during the prodedure.  Also hospitals are quite happy to
>rent out roof space for cellphone masts.
>
>[1] Cardiac Catheter labs that are full of high-tech electronic equipment.

damn! beaten to it.

While I agree with What Chris said, I spent most of august and
september in ICUs around Oxford and the equipment was labelled up for
"no mobiles within 2 metres" so there seems to be some relaxation.

I always remember the hypocrisy of Wisbech Hospital demanding that no
mobiles were switched on even in their grounds and yet they had a
cellsite right on their roof! Several kilo-watts had no effect on
their estate, but <5 watts from a mobile did??? Phenomenon.

On Sat, 8 Dec 2007 13:58:10 +0000, tony sayer 
wrote:

>In article <64cef54d4f%Rail@greywall.demon.co.uk>, Graeme Wall
> scribeth thus
>>In message <4b02gg851j9c.1t6osceq5mt86$.dlg@40tude.net>
>>          Chris  Tolley  wrote:
>>
>>> feebo wrote:
>>> 
>>> > never a single instance of petrol stations
>>> > exploding or planes crashing due to mobile use.
>>> 
>>> However, they can cause havoc in hospitals. I was talking to a
>>> rheumatologist who said that the mobiles interfere with quite a wide
>>> range of medical equipment, and she demonstrated it for me with one of
>>> those doppler scanners that measures blood flow.
>>
>>On the other hand I've been in operating theatres[1] where the surgeon has
>>used a mobile phone during the prodedure.  Also hospitals are quite happy to
>>rent out roof space for cellphone masts.
>
>Subtle difference there Graeme the panel aerials in use at these sites
>direct the radiated field in a controlled fashion away from the site.
>The intensity is in line with the centre of the aerial and not a lot
>gets directed downwards at the site or upwards for that matter...
>
>Course there will be some reflections around the area but the
>intensities will be much less then a mobile at short rages i.e. in a
>room...

not really - local reflections can be very high - remember radio waves
behave just like light in this respect - if you stood on the roof with
a searchlight and shone it at a house 100ys away, you would see it -
the light reflecting back would be weak Unless you found a well
aligned window - more common than you think) because of the poor
reflectivity of the materials used but still good - remembering that
most metallic surfaces will work like a mirror to RF you will get
reflected power very much greater than "a mobile in a room"

On Sat, 08 Dec 2007 10:57:33 GMT, Chris  Tolley 
wrote:

>feebo wrote:
>
>> never a single instance of petrol stations
>> exploding or planes crashing due to mobile use.
>
>However, they can cause havoc in hospitals. I was talking to a
>rheumatologist who said that the mobiles interfere with quite a wide
>range of medical equipment, and she demonstrated it for me with one of
>those doppler scanners that measures blood flow.

forgot to mention also, that easyjet allow passengers to use mobiles
while the plane is taxying between the terminal and runway, so
research has obviously shown there isn't that much problem with the
electronics just they aren't taking the chance at 5 miles up.

Up there they aren't keen on you using much and when the plane is in
between cruise and ground, they like you to turn everything off - even
a GPS unit being used to monitor progress... prolly this is more down
to you paying attention during this most tricky part of the flight.

On Sat, 8 Dec 2007 22:41:01 -0000, "Ivor Jones"
<ivor@despammed.invalid> wrote:

>
>
>"Neil Williams"  wrote in
>message news:475b0e54.633337741@news.individual.net
>: : On Sat, 8 Dec 2007 11:30:39 +0000, tony sayer
>: :  wrote:
>: :
>: : : No give them their due the aircraft environment is a
>: : : very sensitive one and is very safety conscious. If
>: : : there was the slightest risk then they should not be
>: : : allowed but its taken some time to get that far.
>: :
>: : Given that just about every flight these days has one
>: : or two mobiles that their owner has forgotten to turn
>: : off (I've done it), and that we haven't heard of any
>: : accident relating to one, I think you can be reasonably
>: : sure they aren't a big risk.
>
>How do you forget to turn it off once the flight crew have told you to do 
>so before takeoff..?
>
>Ivor


how many people listen to these after the first few times you have
flown - it is easilly done and often ignored.

On Sat, 08 Dec 2007 10:57:33 GMT, Chris  Tolley 
wrote:

>However, they can cause havoc in hospitals. I was talking to a
>rheumatologist who said that the mobiles interfere with quite a wide
>range of medical equipment, and she demonstrated it for me with one of
>those doppler scanners that measures blood flow.

Hmmm... I had to spend a night in hospital a while back. I noticed a
couple of things there:
1. Consultants who'd quite happily use their mobile phones, completely
ignoring the blanket prohibition imposed on patients.
2. Charges for using a phone provided by the hospital were
spectacularly high.

I also remember a former girlfriend, an experienced electronic
engineer whose job was the maintenance of a major hospital's
electronic equipment, telling me that mobile phones posed no real
threat to anything or anyone in the hospital.

Now call me a cynic if you will, but I believe that the only reason
patients are banned from using their phones is to increase the
hospital's profits from the phones which they provide.

If I thought I could obtain a jammer and use it without getting
caught, I would happily do so. Mobile phones are the bane of my life.

Of course, by far the best solution would be to construct all trains
and buses as Faraday cages. Just the quiet coach would be a start, but
there are too many trains that don't have designated quiet coaches.

Peter.

On Sun, 9 Dec 2007 13:21:26 +0000, tony sayer 
wrote:

>No not if their not being used. Yes they do have the odd exchange with
>their net from time to time but a few short duration bursts?..

If they don't have a signal, they attempt to find one using full power
tranmsission a lot more often than they "ping" the network if they do
see one.

Neil

-- 
Neil Williams
Put my first name before the at to reply.

On Sun, 09 Dec 2007 14:19:19 +0000, Peter
 wrote:

>Now call me a cynic if you will, but I believe that the only reason
>patients are banned from using their phones is to increase the
>hospital's profits from the phones which they provide.

I suspect it started off as "don't know what effect it would have, but
don't want to take the risk" but as the risk has become better
understood it's become the latter.

In aviation's case, it's most probably because that industry has (for
very good reason) a culture of safety above all, and that being the
case you really need to *know* it is safe with plenty of testing.
There are, of course, the highly expensive air-phones, but these tend
to be on long-distance flights when you wouldn't get a signal anyway.

There's also another thing to bring into the debate, namely that the
FCC in the US has also banned their use on planes, but not because of
the aircraft itself - rather that they think that a phone moving that
quickly between different cells might cause problems to the mobile
phone networks.

Neil

-- 
Neil Williams
Put my first name before the at to reply.

Neil Williams wrote:
> On Sun, 9 Dec 2007 13:21:26 +0000, tony sayer 
> wrote:
> 
>> No not if their not being used. Yes they do have the odd exchange with
>> their net from time to time but a few short duration bursts?..
> 
> If they don't have a signal, they attempt to find one using full power
> tranmsission a lot more often than they "ping" the network if they do
> see one.

You do not "find" a network by transmitting you find one by receiving -
scanning several channels. Only when you have found one do you transmit.

-- 
Adrian Kennard, on his Mac...
Andrews & Arnold Ltd. Communications specialists.  www.aaisp.net.uk
New UK Wide 03 phone numbers available now.

On Dec 9, 1:21 pm, tony sayer  wrote:
> In article , Neil Williams
>  scribeth thus
>
> >On Sat, 8 Dec 2007 11:30:39 +0000, tony sayer 
> >wrote:
>
> >>No give them their due the aircraft environment is a very sensitive one
> >>and is very safety conscious. If there was the slightest risk then they
> >>should not be allowed but its taken some time to get that far.
>
> >Given that just about every flight these days has one or two mobiles
> >that their owner has forgotten to turn off (I've done it), and that we
> >haven't heard of any accident relating to one, I think you can be
> >reasonably sure they aren't a big risk.
>
> No not if their not being used. Yes they do have the odd exchange with
> their net from time to time but a few short duration bursts?..
>
> Aviation has an excellent safety record, lets keep it that way:))
>
> >Neil
>
> --
> Tony Sayer

Aircraft systems are well shielded but I have personally witnessed the
effect a mobile phone can have when used within 30 feet of a live
cockpit.
1. Radio signals between the controller and the crew are subjected to
a constant rythmic bleeping accompanied by a steady buzz.
2. On a  Jersey European BAE 146 in 2000 (now Flybe) with old style
cockpit using dials. Instrument lights flickered and some dials had
indicators moving rapidly   from side to side. Not by a great deal but
it was described as distracting.
3.  On a much newer CRJ 50 seater using a modern "glass" cockpit the
effect was not noticeable but the radio interference remained.

The basic fact is nobody can guarantee that every type of mobile phone
electronic signature will not in some way affect the many different
types of system on an aircraft. With hundreds of different types of
phone and more appearing almost weekly, who will take responsibility
for EMC testing them against every type of passenger carrying
aircraft? Easier not to take the risk.

On Sat, 08 Dec 2007 10:57:33 GMT someone who may be Chris  Tolley
 wrote this:-

>feebo wrote:
>
>> never a single instance of petrol stations
>> exploding or planes crashing due to mobile use.
>
>However, they can cause havoc in hospitals. I was talking to a
>rheumatologist who said that the mobiles interfere with quite a wide
>range of medical equipment, and she demonstrated it for me with one of
>those doppler scanners that measures blood flow.

Then hospitals have bought badly designed and built equipment. They
probably paid a lot of money for it too.

Many moons ago I occasionally visited a location where mobile
telephones and some other sorts of electrical/electronic equipment
were prohibited, in case they caused a crater in the countryside.
However, the police who enforced these rules were happy to wander
around the site nattering in standard radios, so the rules were
about being seen to do something.


-- 
  David Hansen, Edinburgh 
 I will *always* explain revoked encryption keys, unless RIP prevents me
 http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On Sun, 9 Dec 2007 13:14:30 +0000, tony sayer 
wrote:

>In article , feebo <?@?.?>
>scribeth thus
>>On Sat, 8 Dec 2007 13:58:10 +0000, tony sayer 
>>wrote:
>>
>>>In article <64cef54d4f%Rail@greywall.demon.co.uk>, Graeme Wall
>>> scribeth thus
>>>>In message <4b02gg851j9c.1t6osceq5mt86$.dlg@40tude.net>
>>>>          Chris  Tolley  wrote:
>>>>
>>>>> feebo wrote:
>>>>> 
>>>>> > never a single instance of petrol stations
>>>>> > exploding or planes crashing due to mobile use.
>>>>> 
>>>>> However, they can cause havoc in hospitals. I was talking to a
>>>>> rheumatologist who said that the mobiles interfere with quite a wide
>>>>> range of medical equipment, and she demonstrated it for me with one of
>>>>> those doppler scanners that measures blood flow.
>>>>
>>>>On the other hand I've been in operating theatres[1] where the surgeon has
>>>>used a mobile phone during the prodedure.  Also hospitals are quite happy to
>>>>rent out roof space for cellphone masts.
>>>
>>>Subtle difference there Graeme the panel aerials in use at these sites
>>>direct the radiated field in a controlled fashion away from the site.
>>>The intensity is in line with the centre of the aerial and not a lot
>>>gets directed downwards at the site or upwards for that matter...
>>>
>>>Course there will be some reflections around the area but the
>>>intensities will be much less then a mobile at short rages i.e. in a
>>>room...
>>
>>not really - local reflections can be very high - remember radio waves
>>behave just like light in this respect - if you stood on the roof with
>>a searchlight and shone it at a house 100ys away, you would see it -
>>the light reflecting back would be weak Unless you found a well
>>aligned window - more common than you think) because of the poor
>>reflectivity of the materials used but still good - remembering that
>>most metallic surfaces will work like a mirror to RF you will get
>>reflected power very much greater than "a mobile in a room" 
>>
>Yes .. but the field intensity wont be in the same league as a mobile a
>few feet away.. 

 modern mobys are 2 watts GSM and 1 Watt PCN, inverse square of 2
watts gives tiny W/m2 at even 2 meters from the aerial. At 2W, right
next to a moby antenna, RF field strenght might be as much as 400V/m2
but this tails off rapidly - 900MHz (gsm) has tailed to 120V/m at
1.4cm distant and 1.8GHz (PCN) has dropped to just 70V at the same
distance. Of course equipment (CE no specific shielding) is only
guaranteed to work at 3V/m2 and lower - (this is about 5cm) - which is
why your PC carries on working even if your moby is right on top of it
- you still get i/f but it is tolerable. My cordless mouse gets humpy
if my moby is within 18" or so. 


>
>How are you calculating that then?..

as per section 4 of the Scott report. Inverse square law of radiation
versus distance. Antennas from base station are angled to provide
maximum beam denisity just 50m from the antenna. When taken into
account that the EIRP( Effective Isotropically radiated power) needs
to be consistant, sections of the beam can appear very much stronger
than others, anyone with experience of wireless 802.X networks will
have seen this demonstrated dramatically - one point you have no
coverage, move your laptop six inches to the left and you get
"excellent" local topography can screen or greatly enhance specific
areas of the beam making detailed measurements intricate and
calculation almost einsteinian.

On Sat, 8 Dec 2007 13:58:10 +0000, tony sayer 
wrote:

>In article <64cef54d4f%Rail@greywall.demon.co.uk>, Graeme Wall
> scribeth thus
>>In message <4b02gg851j9c.1t6osceq5mt86$.dlg@40tude.net>
>>          Chris  Tolley  wrote:
>>
>>> feebo wrote:
>>> 
>>> > never a single instance of petrol stations
>>> > exploding or planes crashing due to mobile use.
>>> 
>>> However, they can cause havoc in hospitals. I was talking to a
>>> rheumatologist who said that the mobiles interfere with quite a wide
>>> range of medical equipment, and she demonstrated it for me with one of
>>> those doppler scanners that measures blood flow.
>>
>>On the other hand I've been in operating theatres[1] where the surgeon has
>>used a mobile phone during the prodedure.  Also hospitals are quite happy to
>>rent out roof space for cellphone masts.
>
>Subtle difference there Graeme the panel aerials in use at these sites
>direct the radiated field in a controlled fashion away from the site.
>The intensity is in line with the centre of the aerial and not a lot
>gets directed downwards at the site or upwards for that matter...

sorry... the Stewart report goes into considerable detail concerning
this and states "The main beam is tilted slightly downwards (Figure
4.5) but does not reach ground level until the distance from the tower
is at least 50 m (usually 50–200 m)."

On Sun, 9 Dec 2007 13:19:30 +0000, tony sayer 
wrote:


>
>You reckon thats a much as then,  can you explain how you come to that
>conclusion as I haven't found it to be emitting anything like that!..
>
sorry forgot to reply to this.

The licence for GSM(can't find figures for 1.8GHz stuff or 3G) limits
EIRP to 1.5KW per frequency channel so your challenge about my
"several" is conceded.

Side lobes of the antenna radio profile also mean that some power will
be directed downwards - evidenced by your moby working at the fence on
Churchill Road which google earth gives as about 20m

<feebo> wrote in message news:q0lnl3thnhh2qttt77ljve107ulf7hejg4@4ax.com...
> On Sat, 8 Dec 2007 13:58:10 +0000, tony sayer 
> wrote:
>
>>In article <64cef54d4f%Rail@greywall.demon.co.uk>, Graeme Wall
>> scribeth thus
>>>In message <4b02gg851j9c.1t6osceq5mt86$.dlg@40tude.net>
>>>          Chris  Tolley  wrote:
>>>
>>>> feebo wrote:
>>>>
>>>> > never a single instance of petrol stations
>>>> > exploding or planes crashing due to mobile use.
>>>>
>>>> However, they can cause havoc in hospitals. I was talking to a
>>>> rheumatologist who said that the mobiles interfere with quite a wide
>>>> range of medical equipment, and she demonstrated it for me with one of
>>>> those doppler scanners that measures blood flow.
>>>
>>>On the other hand I've been in operating theatres[1] where the surgeon 
>>>has
>>>used a mobile phone during the prodedure.  Also hospitals are quite happy 
>>>to
>>>rent out roof space for cellphone masts.
>>
>>Subtle difference there Graeme the panel aerials in use at these sites
>>direct the radiated field in a controlled fashion away from the site.
>>The intensity is in line with the centre of the aerial and not a lot
>>gets directed downwards at the site or upwards for that matter...
>>
>>Course there will be some reflections around the area but the
>>intensities will be much less then a mobile at short rages i.e. in a
>>room...
>
> not really - local reflections can be very high - remember radio waves
> behave just like light in this respect - if you stood on the roof with
> a searchlight and shone it at a house 100ys away, you would see it -
> the light reflecting back would be weak Unless you found a well
> aligned window - more common than you think) because of the poor
> reflectivity of the materials used but still good - remembering that
> most metallic surfaces will work like a mirror to RF you will get
> reflected power very much greater than "a mobile in a room"
>


Which will hurt your eye more a 100 watt spotlight reflected off a window a 
few hundred yards away or a 0.5 watt torch bulb close to your eye?  Same 
effect as cellphones, much higher field strength from a nearby mobile phone 
than a cellphone base station.

I have worked around high power RF all my life but do not like to use a 
handheld mobile phone any more than absolutely necessary.

MB

<feebo> wrote in message news:7eusl31er01eokk42vkmqccs0g4hqk6ifr@4ax.com...
> On Sun, 9 Dec 2007 13:14:30 +0000, tony sayer 
> wrote:
>
>>In article , feebo <?@?.?>
>>scribeth thus
>>>On Sat, 8 Dec 2007 13:58:10 +0000, tony sayer 
>>>wrote:
>>>
>>>>In article <64cef54d4f%Rail@greywall.demon.co.uk>, Graeme Wall
>>>> scribeth thus
>>>>>In message <4b02gg851j9c.1t6osceq5mt86$.dlg@40tude.net>
>>>>>          Chris  Tolley  wrote:
>>>>>
>>>>>> feebo wrote:
>>>>>>
>>>>>> > never a single instance of petrol stations
>>>>>> > exploding or planes crashing due to mobile use.
>>>>>>
>>>>>> However, they can cause havoc in hospitals. I was talking to a
>>>>>> rheumatologist who said that the mobiles interfere with quite a wide
>>>>>> range of medical equipment, and she demonstrated it for me with one 
>>>>>> of
>>>>>> those doppler scanners that measures blood flow.
>>>>>
>>>>>On the other hand I've been in operating theatres[1] where the surgeon 
>>>>>has
>>>>>used a mobile phone during the prodedure.  Also hospitals are quite 
>>>>>happy to
>>>>>rent out roof space for cellphone masts.
>>>>
>>>>Subtle difference there Graeme the panel aerials in use at these sites
>>>>direct the radiated field in a controlled fashion away from the site.
>>>>The intensity is in line with the centre of the aerial and not a lot
>>>>gets directed downwards at the site or upwards for that matter...
>>>>
>>>>Course there will be some reflections around the area but the
>>>>intensities will be much less then a mobile at short rages i.e. in a
>>>>room...
>>>
>>>not really - local reflections can be very high - remember radio waves
>>>behave just like light in this respect - if you stood on the roof with
>>>a searchlight and shone it at a house 100ys away, you would see it -
>>>the light reflecting back would be weak Unless you found a well
>>>aligned window - more common than you think) because of the poor
>>>reflectivity of the materials used but still good - remembering that
>>>most metallic surfaces will work like a mirror to RF you will get
>>>reflected power very much greater than "a mobile in a room"
>>>
>>Yes .. but the field intensity wont be in the same league as a mobile a
>>few feet away..
>
> modern mobys are 2 watts GSM and 1 Watt PCN, inverse square of 2
> watts gives tiny W/m2 at even 2 meters from the aerial. At 2W, right
> next to a moby antenna, RF field strenght might be as much as 400V/m2
> but this tails off rapidly - 900MHz (gsm) has tailed to 120V/m at
> 1.4cm distant and 1.8GHz (PCN) has dropped to just 70V at the same
> distance. Of course equipment (CE no specific shielding) is only
> guaranteed to work at 3V/m2 and lower - (this is about 5cm) - which is
> why your PC carries on working even if your moby is right on top of it
> - you still get i/f but it is tolerable. My cordless mouse gets humpy
> if my moby is within 18" or so.
>
>
>>
>>How are you calculating that then?..
>
> as per section 4 of the Scott report. Inverse square law of radiation
> versus distance. Antennas from base station are angled to provide
> maximum beam denisity just 50m from the antenna. When taken into
> account that the EIRP( Effective Isotropically radiated power) needs
> to be consistant, sections of the beam can appear very much stronger
> than others, anyone with experience of wireless 802.X networks will
> have seen this demonstrated dramatically - one point you have no
> coverage, move your laptop six inches to the left and you get
> "excellent" local topography can screen or greatly enhance specific
> areas of the beam making detailed measurements intricate and
> calculation almost einsteinian.


A colleague was involved in some measurements after someone was complaining 
about RF from a tower next to his house (the transmitting station had been 
there for years when he built his house).  They had proper measuring gear 
but could hardly detect any RF around his house.  I asked him if he had 
tried measuring a handheld mobile phone, the meter went off the scale when 
the detector was held near the phone.

MB

<feebo> wrote in message news:af3tl31iaqg14p7u1hvvk53np39f8lnnn9@4ax.com...
> On Sun, 9 Dec 2007 13:19:30 +0000, tony sayer 
> wrote:
>
>
>>
>>You reckon thats a much as then,  can you explain how you come to that
>>conclusion as I haven't found it to be emitting anything like that!..
>>
> sorry forgot to reply to this.
>
> The licence for GSM(can't find figures for 1.8GHz stuff or 3G) limits
> EIRP to 1.5KW per frequency channel so your challenge about my
> "several" is conceded.
>
> Side lobes of the antenna radio profile also mean that some power will
> be directed downwards - evidenced by your moby working at the fence on
> Churchill Road which google earth gives as about 20m


It is quite common to have difficulty using a mobile phone near a base 
station because the phone registers on distant sites and not unknown for 
those site to be outside 24(?) mile range of GSM.

MB

On Tue, 11 Dec 2007 14:36:51 -0000, "MB" <mb@invalid.invalid> wrote:


>It is quite common to have difficulty using a mobile phone near a base 
>station because the phone registers on distant sites and not unknown for 
>those site to be outside 24(?) mile range of GSM.
>
>MB 
>

I have *never* had difficulty using a moby near cell-sites. been
around several today and each time I check my N95 is reporting (not
surprisingly) full signal with a postit note stuck on with some more
pegs drawn on it. If what you say is true then it would make no sense
to site so many masts close to main roads and railways. Why not put
them back 200m from the road to prevent drop-outs as you pass? Why?
Coz it is not an issue.

On Tue, 11 Dec 2007 14:31:08 -0000, "MB" <mb@invalid.invalid> wrote:

>
><feebo> wrote in message news:q0lnl3thnhh2qttt77ljve107ulf7hejg4@4ax.com...
>> On Sat, 8 Dec 2007 13:58:10 +0000, tony sayer 
>> wrote:
>>
>>>In article <64cef54d4f%Rail@greywall.demon.co.uk>, Graeme Wall
>>> scribeth thus
>>>>In message <4b02gg851j9c.1t6osceq5mt86$.dlg@40tude.net>
>>>>          Chris  Tolley  wrote:
>>>>
>>>>> feebo wrote:
>>>>>
>>>>> > never a single instance of petrol stations
>>>>> > exploding or planes crashing due to mobile use.
>>>>>
>>>>> However, they can cause havoc in hospitals. I was talking to a
>>>>> rheumatologist who said that the mobiles interfere with quite a wide
>>>>> range of medical equipment, and she demonstrated it for me with one of
>>>>> those doppler scanners that measures blood flow.
>>>>
>>>>On the other hand I've been in operating theatres[1] where the surgeon 
>>>>has
>>>>used a mobile phone during the prodedure.  Also hospitals are quite happy 
>>>>to
>>>>rent out roof space for cellphone masts.
>>>
>>>Subtle difference there Graeme the panel aerials in use at these sites
>>>direct the radiated field in a controlled fashion away from the site.
>>>The intensity is in line with the centre of the aerial and not a lot
>>>gets directed downwards at the site or upwards for that matter...
>>>
>>>Course there will be some reflections around the area but the
>>>intensities will be much less then a mobile at short rages i.e. in a
>>>room...
>>
>> not really - local reflections can be very high - remember radio waves
>> behave just like light in this respect - if you stood on the roof with
>> a searchlight and shone it at a house 100ys away, you would see it -
>> the light reflecting back would be weak Unless you found a well
>> aligned window - more common than you think) because of the poor
>> reflectivity of the materials used but still good - remembering that
>> most metallic surfaces will work like a mirror to RF you will get
>> reflected power very much greater than "a mobile in a room"
>>
>
>
>Which will hurt your eye more a 100 watt spotlight reflected off a window a 
>few hundred yards away or a 0.5 watt torch bulb close to your eye?  Same 
>effect as cellphones, much higher field strength from a nearby mobile phone 
>than a cellphone base station.

tosh... that is like saying what would you prefer a furnace a mile
away or a soldering iron up your jacksi. Have you never been blinded
by a car half a mile behind you with full beam relecting off your
rear-view mirror? 2x55W

This is a moot point anyway because we are not discussing light - I
used that merely as an illustration for lay-people how RF can relect
in like manner.

>
>I have worked around high power RF all my life but do not like to use a 
>handheld mobile phone any more than absolutely necessary.

That is your choice and it is expressed by many - I must agree that
years ago my Orbitel 902 (one of the first GSM handsets) did seem to
give me a headache but I never could pin down whether that was
psycosomatic or not. There is more chance it was related to the
transmition pattern of GSM than the power involved - this page touches
on a possibility http://techmind.org/gsm/

On Tue, 11 Dec 2007 22:07:22 +0000, tony sayer 
wrote:


>
>Eh?..

ok, ok... point taken :o) this is a railway grp after all.

<doffs cap>

In article , feebo <?@?.?>
scribeth thus
>On Tue, 11 Dec 2007 22:07:22 +0000, tony sayer 
>wrote:
>
>
>>
>>Eh?..
>
>ok, ok... point taken :o) this is a railway grp after all.
>
><doffs cap>

;)...

doffs cap eh?..

Now thats something..
-- 
Tony Sayer

Neil Williams wrote:

> If they don't have a signal, they attempt to find one using full power
> tranmsission a lot more often than they "ping" the network if they do
> see one.

Not true. If they don't see a signal, they don't transmit at all.

On Fri, 04 Jan 2008 21:46:39 +0000, Iain 
wrote:

>Neil Williams wrote:
>
>> If they don't have a signal, they attempt to find one using full power
>> tranmsission a lot more often than they "ping" the network if they do
>> see one.
>
>Not true. If they don't see a signal, they don't transmit at all.

not quite, they'll periodically poll to see if a network is there, and
if there is one if it's one the phone can use.

Otherwise when you went out of coverage you'd never go back in
coverage when the network came back short of power cycling the phone.

"Gavin"  wrote in message 
news:dahun354lhemouuc0ffdmkdt8end7molb0@4ax.com...
> On Fri, 04 Jan 2008 21:46:39 +0000, Iain 
> wrote:
>
>>Neil Williams wrote:
>>
>>> If they don't have a signal, they attempt to find one using full power
>>> tranmsission a lot more often than they "ping" the network if they do
>>> see one.
>>
>>Not true. If they don't see a signal, they don't transmit at all.
>
> not quite, they'll periodically poll to see if a network is there, and
> if there is one if it's one the phone can use.
>
> Otherwise when you went out of coverage you'd never go back in
> coverage when the network came back short of power cycling the phone.

Poll implies that they transmit, I thought the phone would scan around 
looking for a suitable network and then try to register on the strongest 
signal.

I also thought that when out of range the interval between the phone doing a 
search got longer but it would keep trying.  Cycling the phone can just 
speed things up.

One problem with jamming or screening that if the phone receives a signal 
from a base station then it will go onto its highest power to try to 
register and stay registered.  So any interference could be worst that it 
would be otherwise.

MB

On Sat, 05 Jan 2008 08:50:47 GMT, Gavin  wrote:

>On Fri, 04 Jan 2008 21:46:39 +0000, Iain 
>wrote:
>
>>Neil Williams wrote:
>>
>>> If they don't have a signal, they attempt to find one using full power
>>> tranmsission a lot more often than they "ping" the network if they do
>>> see one.
>>
>>Not true. If they don't see a signal, they don't transmit at all.
>
>not quite, they'll periodically poll to see if a network is there, and
>if there is one if it's one the phone can use.
>
>Otherwise when you went out of coverage you'd never go back in
>coverage when the network came back short of power cycling the phone.

But do they actually need to transmit a signal in order to detect the
presence of a network? Couldn't the phone just periodically scan for
received signals and only transmit when attempting to register on a
network?

Chris

Chris Blunt  wrote in message
:

>On Sat, 05 Jan 2008 08:50:47 GMT, Gavin  wrote:
>
>>On Fri, 04 Jan 2008 21:46:39 +0000, Iain 
>>wrote:
>>
>>>Neil Williams wrote:
>>>
>>>> If they don't have a signal, they attempt to find one using full power
>>>> tranmsission a lot more often than they "ping" the network if they do
>>>> see one.
>>>
>>>Not true. If they don't see a signal, they don't transmit at all.
>>
>>not quite, they'll periodically poll to see if a network is there, and
>>if there is one if it's one the phone can use.
>>
>>Otherwise when you went out of coverage you'd never go back in
>>coverage when the network came back short of power cycling the phone.
>
>But do they actually need to transmit a signal in order to detect the
>presence of a network? Couldn't the phone just periodically scan for
>received signals and only transmit when attempting to register on a
>network?

No, Iain's post was completely and utterly correct.  If a signal is not
recieved the phone doesn't transmit. Ever. 

The "Periodic poll" from Gavin is either poorly worded or the statement
of someone who doesn't know what they're talking about.  In any case it
added nothing of any value to the thread.

On Sat, 5 Jan 2008 10:46:12 -0000, "MB" <mb@invalid.invalid> wrote:

>
>"Gavin"  wrote in message 
>news:dahun354lhemouuc0ffdmkdt8end7molb0@4ax.com...
>> On Fri, 04 Jan 2008 21:46:39 +0000, Iain 
>> wrote:
>>
>>>Neil Williams wrote:
>>>
>>>> If they don't have a signal, they attempt to find one using full power
>>>> tranmsission a lot more often than they "ping" the network if they do
>>>> see one.
>>>
>>>Not true. If they don't see a signal, they don't transmit at all.
>>
>> not quite, they'll periodically poll to see if a network is there, and
>> if there is one if it's one the phone can use.
>>
>> Otherwise when you went out of coverage you'd never go back in
>> coverage when the network came back short of power cycling the phone.
>
>Poll implies that they transmit, I thought the phone would scan around 
>looking for a suitable network and then try to register on the strongest 
>signal.
>
>I also thought that when out of range the interval between the phone doing a 
>search got longer but it would keep trying.  Cycling the phone can just 
>speed things up.
>
>One problem with jamming or screening that if the phone receives a signal 
>from a base station then it will go onto its highest power to try to 
>register and stay registered.  So any interference could be worst that it 
>would be otherwise.
>
Even if the phone sat in what amounted to "listen only" mode it would
still have to transmit to an available base station at intervals to
let the system know that it was active otherwise the system would
assume it was no longer active or within range.

On Sat, 05 Jan 2008 11:58:19 +0000, deadmail@burnt.org.uk wrote:

> Chris Blunt  wrote in message
>:
>
>>On Sat, 05 Jan 2008 08:50:47 GMT, Gavin  wrote:
>>
>>>On Fri, 04 Jan 2008 21:46:39 +0000, Iain 
>>>wrote:
>>>
>>>>Neil Williams wrote:
>>>>
>>>>> If they don't have a signal, they attempt to find one using full power
>>>>> tranmsission a lot more often than they "ping" the network if they do
>>>>> see one.
>>>>
>>>>Not true. If they don't see a signal, they don't transmit at all.
>>>
>>>not quite, they'll periodically poll to see if a network is there, and
>>>if there is one if it's one the phone can use.
>>>
>>>Otherwise when you went out of coverage you'd never go back in
>>>coverage when the network came back short of power cycling the phone.
>>
>>But do they actually need to transmit a signal in order to detect the
>>presence of a network? Couldn't the phone just periodically scan for
>>received signals and only transmit when attempting to register on a
>>network?
>
>No, Iain's post was completely and utterly correct.  If a signal is not
>recieved the phone doesn't transmit. Ever. 
>
>The "Periodic poll" from Gavin is either poorly worded or the statement
>of someone who doesn't know what they're talking about.  In any case it
>added nothing of any value to the thread.


My understaning was that the phone will try and transmit to the
network at periodic intervals to try and reregister. Usually if the
phone has recieved a signal of some sort but cannot determine if it's
it's own network, but can also be done if the phone has no signal at
all.  Bear in ming no signal on the display does not mean no signal it
means no signal useable tothe phone, another network may be present
but it's not permitted to roam on to it.    Whilst the time interval
between these polls increases as it gets no reply it still performs
them.