"the jammers revenge on mobile prattlers" in the Times

In message
19ca30d9-74bc-4c00-8b14-f4c2b5a2f7a7...oglegroups.com,
Mizter T <[email protected]> Proclaimed from the tallest tower:

> On 6 Dec, 00:16, "Ivor Jones" <[email protected]> wrote:
>> "tony sayer" <[email protected]> wrote in message
>>
>> news:[email protected]
>>>> In article <[email protected]>, alexd
>>>> <[email protected]> scribeth thus
>>>>> tony sayer wrote:
>>>>>
>>>>>> In article
>>>>>> <[email protected]>,
>>>>>> MichaelJP <[email protected]> scribeth thus
>>>>>
>>>>>>> Radio comms in a surface environment is subject
>>>>>>> to all sorts of interference and certainly can't
>>>>>>> be relied on for "mission critical" applications.
>>>>>
>>>>>> Umm...Aircraft comms anyone?...
>>>>>
>>>>> What about it?
>>>>>
>>>> Well "mission critical" is it not?..
>>
>> <pedant>
>>
>> It's not a "surface" environment either..!
>>
>> </pedant>
>>
>> Ivor
>
> ?
>
> I dispute you're pedantry - I can't see what on earth is wrong with
> calling predominantly non-subterranean railways a "surface
> environment"?

I think he was refering to aircraft comms... (?)

--
Regards,
Chris.
(Remove Elvis's shoes to email me)

---

› See More: "the jammers revenge on mobile prattlers" in the Times

Alasdair <[email protected]> wrote:

> On Tue, 4 Dec 2007 14:44:03 +0000 (UTC), Mike Civil
> <[email protected]> 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.

On 6 Dec, 11:24, "ChrisM" <[email protected]> wrote:
> In message
> 19ca30d9-74bc-4c00-8b14-f4c2b5a2f...@s19g2000prg.googlegroups.com,
> Mizter T <[email protected]> Proclaimed from the tallest tower:
>
>
> > On 6 Dec, 00:16, "Ivor Jones" <[email protected]> wrote:
> >> "tony sayer" <[email protected]> wrote:
>
>
> >>>> In article <[email protected]>, alexd
> >>>> <[email protected]> scribeth thus
> >>>>> tony sayer wrote:
>
> >>>>>> In article
> >>>>>> <[email protected]>,
> >>>>>> MichaelJP <[email protected]> scribeth thus
>
> >>>>>>> Radio comms in a surface environment is subject
> >>>>>>> to all sorts of interference and certainly can't
> >>>>>>> be relied on for "mission critical" applications.
>
> >>>>>> Umm...Aircraft comms anyone?...
>
> >>>>> What about it?
>
> >>>> Well "mission critical" is it not?..
>
> >> <pedant>
>
> >> It's not a "surface" environment either..!
>
> >> </pedant>
>
> >> Ivor
>
> > ?
>
> > I dispute you're pedantry - I can't see what on earth is wrong with
> > calling predominantly non-subterranean railways a "surface
> > environment"?
>
> I think he was refering to aircraft comms... (?)


Yes, looking back on the exchange I think he was too. Oops.

"Nomen Nescio" <[email protected]> wrote in message
news:[email protected]...
..
>
>> 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®"
<[email protected]> 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 <[email protected]>
wrote:

>On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
><[email protected]> 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 <[email protected]>
Alasdair <[email protected]> wrote:

> On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
> <[email protected]> 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>

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 article <[email protected]>, Alasdair
<[email protected]> scribeth thus
>On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
><[email protected]> 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

In article <[email protected]>, John Williamson
<[email protected]> 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" <[email protected]> wrote in message
news:ff4ce34d4f%[email protected]...
> In message <[email protected]>
> Alasdair <[email protected]> wrote:
>
>> On Fri, 7 Dec 2007 19:51:22 -0000, "Trust No One®"
>> <[email protected]> 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.

On Sat, 8 Dec 2007 11:30:39 +0000, tony sayer <[email protected]>
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.