Re: "the jammers revenge on mobile prattlers" in the Times

In article <475b0e54.633337741@news.individual.net>, Neil Williams
<wensleydale@pacersplace.org.uk> scribeth thus
>On Sat, 8 Dec 2007 11:30:39 +0000, tony sayer <tony@bancom.co.uk>
>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

On Sun, 9 Dec 2007 13:21:26 +0000, tony sayer <tony@bancom.co.uk>
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.

Neil Williams wrote:
> On Sun, 9 Dec 2007 13:21:26 +0000, tony sayer <tony@bancom.co.uk>
> 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 <t...@bancom.co.uk> wrote:
> In article <475b0e54.633337...@news.individual.net>, Neil Williams
> <wensleyd...@pacersplace.org.uk> scribeth thus
>
> >On Sat, 8 Dec 2007 11:30:39 +0000, tony sayer <t...@bancom.co.uk>
> >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.

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.

"Gavin" <gavin@mindless.com> wrote in message
news:dahun354lhemouuc0ffdmkdt8end7molb0@4ax.com...
> On Fri, 04 Jan 2008 21:46:39 +0000, Iain <no-one@hairydog.co.uk>
> 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 <gavin@mindless.com> wrote:

>On Fri, 04 Jan 2008 21:46:39 +0000, Iain <no-one@hairydog.co.uk>
>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

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

>
>"Gavin" <gavin@mindless.com> wrote in message
>news:dahun354lhemouuc0ffdmkdt8end7molb0@4ax.com.. .
>> On Fri, 04 Jan 2008 21:46:39 +0000, Iain <no-one@hairydog.co.uk>
>> 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 2008-01-05, MB <mb@invalid.invalid> wrote:
>
> 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.

As long as the interference lowers the SNR sufficiently, the phone won't
be able to hear the base station anyway.

--
David Taylor

On 2008-01-05, Charles Ellson <charles@ellson.demon.co.uk> wrote:
>
> 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.

When the phone can't hear a base station there is nothing
to transmit to!

--
David Taylor

On Sat, 5 Jan 2008 21:33:24 +0000 (UTC), David Taylor
<davidt-news@yadt.co.uk> wrote:

>On 2008-01-05, Charles Ellson <charles@ellson.demon.co.uk> wrote:
>>
>> 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.
>
>When the phone can't hear a base station there is nothing
>to transmit to!
>
If you unsnip the immediately preceding paragraph you'll find the
subject was a phone within range of a base station. I was merely
indicating that "conversation" between the 'phone and base station
continues at intervals after the initial connection is established.