short range, directional mobile phone jammer?

On 7 Aug, 16:39, paranoid bob <[email protected]> wrote:

> I sit quietly. I don't smell, talk on my phone, play music or make any
> other noises that anyone else can hear, or put things on the next seat
> to discourage someone else from sitting there.

Sanctimonious bastards are just so annoying ...

Ian

---

› See More: short range, directional mobile phone jammer?

"Ian" <[email protected]> wrote in message
news:[email protected]...
> On 7 Aug, 16:39, paranoid bob <[email protected]> wrote:
>
>> I sit quietly. I don't smell, talk on my phone, play music or make any
>> other noises that anyone else can hear, or put things on the next seat
>> to discourage someone else from sitting there.
>
> Sanctimonious bastards are just so annoying ...

In which case I'm a sanctimonious bastard as well, because I refrain from
eating noisy or smelly food, playing music loudly or talking loudly on my
mobile phone - indeed if I do use my mobile, I will sometimes turn towards
the wall or seat back to muffle the sound of my voice.

However I am guilty of putting my bag on the adjacent seat to discourage
people from sitting there, moving it only if an attractive lass is walking
up to the seat! ;-)

"R. Mark Clayton" <[email protected]> wrote:

> > Anyone know where I could find a short range (10 feet max), short
> > burst (just long enough to disconnect a call), directional mobile
> > phone jammer? Just to disconnect loudmouths on the train, directional
> > so it doesn't affect someone quietly texting in different direction?
> >
> > thanks
> >
>
> Given that mobile phones still work under pantograph wires and under bridges
> etc. (but not tunnels) you will need a fairly long burst, and pretty high
> energy to defeat a frequency agile GSM. In any event you would only mess up
> the receive segment. The phone would hand off to another base station in
> another direction fairly soon too. With CDMA or UMTS you would have even
> less luck.

A friend who knows or thinks he knows (!) a bit about electronics said
that the way to do this would be to generate white noise and modulate
it to a band around the main frequency (900 or 1800 megahertz, I think
he said).

?

Ah. A sanctmonious perv. bastard then.

"Mortimer" <[email protected]> wrote in message
news:[email protected]...
> "Ian" <[email protected]> wrote in message
> news:[email protected]...
>> On 7 Aug, 16:39, paranoid bob <[email protected]> wrote:
>>
>>> I sit quietly. I don't smell, talk on my phone, play music or make any
>>> other noises that anyone else can hear, or put things on the next seat
>>> to discourage someone else from sitting there.
>>
>> Sanctimonious bastards are just so annoying ...
>
> In which case I'm a sanctimonious bastard as well, because I refrain from
> eating noisy or smelly food, playing music loudly or talking loudly on my
> mobile phone - indeed if I do use my mobile, I will sometimes turn towards
> the wall or seat back to muffle the sound of my voice.
>
> However I am guilty of putting my bag on the adjacent seat to discourage
> people from sitting there, moving it only if an attractive lass is walking
> up to the seat! ;-)
>

Yes, guilty as charged ;-)

Well I'd rather have a pretty woman to talk to instead of trying to avoid
shoulder/arm contact with Mister Blobby! Sadly I always seem to draw the
short straw ;-(


"notbresson" <[email protected]> wrote in message
news:[email protected]...
> Ah. A sanctmonious perv. bastard then.
>
> "Mortimer" <[email protected]> wrote in message
> news:[email protected]...
>> "Ian" <[email protected]> wrote in message
>> news:[email protected]...
>>> On 7 Aug, 16:39, paranoid bob <[email protected]> wrote:
>>>
>>>> I sit quietly. I don't smell, talk on my phone, play music or make any
>>>> other noises that anyone else can hear, or put things on the next seat
>>>> to discourage someone else from sitting there.
>>>
>>> Sanctimonious bastards are just so annoying ...
>>
>> In which case I'm a sanctimonious bastard as well, because I refrain from
>> eating noisy or smelly food, playing music loudly or talking loudly on my
>> mobile phone - indeed if I do use my mobile, I will sometimes turn
>> towards the wall or seat back to muffle the sound of my voice.
>>
>> However I am guilty of putting my bag on the adjacent seat to discourage
>> people from sitting there, moving it only if an attractive lass is
>> walking up to the seat! ;-)
>>
>
>

<paranoid bob <[email protected]>> wrote in message
news:[email protected]...
> "R. Mark Clayton" <[email protected]> wrote:
>
>> > Anyone know where I could find a short range (10 feet max), short
>> > burst (just long enough to disconnect a call), directional mobile
>> > phone jammer? Just to disconnect loudmouths on the train, directional
>> > so it doesn't affect someone quietly texting in different direction?
>> >
>> > thanks
>> >
>>
>> Given that mobile phones still work under pantograph wires and under
>> bridges
>> etc. (but not tunnels) you will need a fairly long burst, and pretty high
>> energy to defeat a frequency agile GSM. In any event you would only mess
>> up
>> the receive segment. The phone would hand off to another base station in
>> another direction fairly soon too. With CDMA or UMTS you would have even
>> less luck.
>
> A friend who knows or thinks he knows (!) a bit about electronics said
> that the way to do this would be to generate white noise and modulate
> it to a band around the main frequency (900 or 1800 megahertz, I think
> he said).
>
> ?

What do you think the spark on the power pick up does - not only that it is
connected to a bloody good aerial (the wire).

Without knowledge of the precise times and frequencies that the particular
phone is using it would require a lot of energy to effectively jam it (and
then probably only one way). Sat with this in your lap, Lenny would soon be
using you as proof of his theories about EMF causing injury (enough will).
Not only that but you would get nicked.

"Bob Eager" <[email protected]> wrote in message
news:[email protected]

> No, the loudmouths are the self-important twats...

A loudmouth is a loudmouth. I've always found the english way is to suffer
in silence, or heavens above, confront the loudmouth.

> the rest of us just
> want a quiet life.

Maybe, but the OP obviously sees it as his divine right to terminate the
communication of anyone he doesn't like. That's a form of loudmouthery all
of its' own. I'm sure we'd all think him a true hero if his device
interfered with Cab Secure Radio or Radio Tokenless Block signalling
equipment.

I hate loudmouths as much as anyone else; however I object to anyone else
deeming themselves the right to jam me should I need to use my phone in such
a place, be it text, GPRS or voice.

Tim

--
Sent from Birmingham, UK... Check out www.nervouscyclist.org
'I find sometimes it's easy to be myself, but sometimes I find it's
better to be somebody else.' - Dave Matthews 'So Much To Say'
My 'reply to' address is valid, mail to the posting address is dumped

On 2007-08-07, R. Mark Clayton <[email protected]> wrote:
><paranoid bob <[email protected]>> wrote in message
> news:[email protected]...
>> "R. Mark Clayton" <[email protected]> wrote:
>>
>>> > Anyone know where I could find a short range (10 feet max), short
>>> > burst (just long enough to disconnect a call), directional mobile
>>> > phone jammer? Just to disconnect loudmouths on the train, directional
>>> > so it doesn't affect someone quietly texting in different direction?
>>> >
>>> > thanks
>>> >
>>>
>>> Given that mobile phones still work under pantograph wires and under
>>> bridges
>>> etc. (but not tunnels) you will need a fairly long burst, and pretty high
>>> energy to defeat a frequency agile GSM. In any event you would only mess
>>> up
>>> the receive segment. The phone would hand off to another base station in
>>> another direction fairly soon too. With CDMA or UMTS you would have even
>>> less luck.
>>
>> A friend who knows or thinks he knows (!) a bit about electronics said
>> that the way to do this would be to generate white noise and modulate
>> it to a band around the main frequency (900 or 1800 megahertz, I think
>> he said).
>>
>> ?
>
> What do you think the spark on the power pick up does - not only that it is
> connected to a bloody good aerial (the wire).
>
> Without knowledge of the precise times and frequencies that the particular
> phone is using it would require a lot of energy to effectively jam it (and
> then probably only one way). Sat with this in your lap, Lenny would soon be
> using you as proof of his theories about EMF causing injury (enough will).
> Not only that but you would get nicked.

I don't think it is that bad. You only need to block one transmission
direction to disconnect the call; if you are closer to the phone than the
tower the tower->phone direction would be the one to pick. I think GSM
phones require at least a 6 dB signal-to-noise ratio to operate, so if you
can put a signal on the phone's receive channel at about the same power
level as the the tower you'll block it. I think the tower is limited to
less than 2 Watts (32 dBmW) per GSM channel. If the tower is 1 km away
from the phone and you are 10 m away you'll need to get 1/10,000th of the
tower's output power on the channel to match it, or about 200 uW. There
are 124 channels in the 900 MHz band and 374 channels at 1800 MHz, so to
cover all channels at once at 200 uW would take about 25 mW for the
900 MHz band and 75 mW for 1800 MHz, 100 mW total. If I haven't made
a mistake it seems the jammer would need a lower power output than mobile
handsets typically produce to block all the channels in both bands at once
to a distance of 10 meters. And the transmission isn't pulsed, so Lenny
might be happy.

As for getting caught, I've read anecdotes about what it took to locate
low-level, bandband sources of unintentional interference to GPS receivers
and this was not all that easy even when the interference was broadcast
continuously. I'm not sure how they'd find a broadband 100 mW source
that was turned on for only a minute or two every once in a while.

I think a jammer that blocks all GSM channels would be fairly straight
forward to build. I hope this doesn't become popular.

Dennis Ferguson

["Followup-To:" header set to alt.cellular.]
On 2007-08-07, Bob Eager <[email protected]> wrote:

>> Since train signallers and some railway radio systems use GSM, would you
>> really want to risk intefering with the safety just because you're a
>> self-important twat?
>
> No, the loudmouths are the self-important twats...the rest of us just
> want a quiet life.

Yes, the loudmouths are selfish, but so are you if you would interfere with
the safe operation of a train in order to shut them up. Besides, cause an
accident and get caught with one of those things and you'll probably get
into quite a bit of trouble.

On Tue, 07 Aug 2007 21:19:23 GMT, Dennis Ferguson
<[email protected]> wrote:

<Big Snip>
>
>I think a jammer that blocks all GSM channels would be fairly straight
>forward to build. I hope this doesn't become popular.
>

Especially after Network Rail roll out GSM-R which operates on
reserved channels in the same 900 MHz band.

http://www.networkrail.co.uk/aspx/3606.aspx

The same jammer could be knocking out safety critical comms.

On 07/08/2007 15:00, paranoid bob wrote:

> Search for what on google? I can only find them with too long a range;
> even this
> http://www.globalgadgetuk.com/Personal.htm
> is too far-reaching at 10 metres.

If you want shorter range than 10m you might as well use your fist,
because if you use a jammer at that close-range, it's only a matter of
time before somebody catches you at it and uses theirs!

On Tue, 7 Aug 2007 21:21:19 UTC, Steve Sobol <[email protected]>
wrote:

> ["Followup-To:" header set to alt.cellular.]
> On 2007-08-07, Bob Eager <[email protected]> wrote:
>
> >> Since train signallers and some railway radio systems use GSM, would you
> >> really want to risk intefering with the safety just because you're a
> >> self-important twat?
> >
> > No, the loudmouths are the self-important twats...the rest of us just
> > want a quiet life.
>
> Yes, the loudmouths are selfish, but so are you if you would interfere with
> the safe operation of a train in order to shut them up.

You miss the point. I said nothing about the rights and wrongs of using
the equipment.


--
Bob Eager
begin 123 a new life...take up Extreme Ironing!

On 2007-08-07, Bob Eager <[email protected]> wrote:

>> Yes, the loudmouths are selfish, but so are you if you would interfere with
>> the safe operation of a train in order to shut them up.
>
> You miss the point. I said nothing about the rights and wrongs of using
> the equipment.

I'm not saying you did. I'm saying if you're going to complain about others
being selfish, you should consider whether your own solution suffers from
the same problem. It's the whole Let-He-Who-Is-Without-Sin-Cast-Stones-From-
Inside-His-Glass-House concept.

On Tue, 07 Aug 2007 16:56:29 GMT, "notbresson"
<[email protected]> wrote:

>"Mortimer" <[email protected]> wrote in message
>news:[email protected]...
>> "Ian" <[email protected]> wrote in message
>> news:[email protected]...
>>> On 7 Aug, 16:39, paranoid bob <[email protected]> wrote:
>>>
>>>> I sit quietly. I don't smell, talk on my phone, play music or make any
>>>> other noises that anyone else can hear, or put things on the next seat
>>>> to discourage someone else from sitting there.
>>>
>>> Sanctimonious bastards are just so annoying ...
>>
>> In which case I'm a sanctimonious bastard as well, because I refrain from
>> eating noisy or smelly food, playing music loudly or talking loudly on my
>> mobile phone - indeed if I do use my mobile, I will sometimes turn towards
>> the wall or seat back to muffle the sound of my voice.
>>
>> However I am guilty of putting my bag on the adjacent seat to discourage
>> people from sitting there, moving it only if an attractive lass is walking
>> up to the seat! ;-)
>>
>
>Ah. A sanctmonious perv. bastard then.
>
Sounds perfectly normal to me, but it might not to a <stereotype>
train-spotter </stereotype>.

On Aug 8, 11:41 am, CJB <[email protected]> wrote:
> > On Tue, 07 Aug 2007 16:56:29 GMT, "notbresson"
> > >>>> I sit quietly. I don't smell, talk on my phone, play music or make any
> > >>>> other noises that anyone else can hear, or put things on the next seat
> > >>>> to discourage someone else from sitting there.
>
> The mobile phone jammers are called WaveWalls. They're illegal in the
> UK. They can be purchased from Japan. CJB.

Actually search newsgroup sci.engr.electrical.compliance for "wall
wave mobile phone"

CJB.