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

John Williamson

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.

Graeme Wall

In message <bivjl3l8p00l1m2vq63c5qnb9t3m6uk19c@4ax.com>
Alasdair <mail@bobaxter.coo.uk> wrote:

> On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
> <dana.scully@usa.xnet> 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>

Ian Smith

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

tony sayer

In article <bivjl3l8p00l1m2vq63c5qnb9t3m6uk19c@4ax.com>, Alasdair
<mail@bobaxter.coo.uk> scribeth thus
>On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
><dana.scully@usa.xnet> 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.
>

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.

--
Tony Sayer

tony sayer

In article <fjdbd6$6vl$1@stable.tornevall.net>, John Williamson
<johnwilliamson@btinternet.com> scribeth thus
>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.

Not quite true.. If your sideways on to a BST the relative speed will be
much less...

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

Graeme Wall

In message <bivjl3l8p00l1m2vq63c5qnb9t3m6uk19c@4ax.com>
Alasdair <mail@bobaxter.coo.uk> wrote:

> On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
> <dana.scully@usa.xnet> 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>

Ian Smith

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

tony sayer

In article <bivjl3l8p00l1m2vq63c5qnb9t3m6uk19c@4ax.com>, Alasdair
<mail@bobaxter.coo.uk> scribeth thus
>On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
><dana.scully@usa.xnet> 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.
>

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.

--
Tony Sayer

tony sayer

In article <fjdbd6$6vl$1@stable.tornevall.net>, John Williamson
<johnwilliamson@btinternet.com> scribeth thus
>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.

Not quite true.. If your sideways on to a BST the relative speed will be
much less...

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

Woody

"Graeme Wall" <Rail@greywall.demon.co.uk> wrote in message
news:ff4ce34d4f%Rail@greywall.demon.co.uk...
> In message <bivjl3l8p00l1m2vq63c5qnb9t3m6uk19c@4ax.com>
> Alasdair <mail@bobaxter.coo.uk> wrote:
>
>> On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
>> <dana.scully@usa.xnet> 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