"Nomen Nescio" wrote in message
...
According to an article in the Register, Anil Vora has invented a
handheld phone jammer for about £30.

http://www.theregister.co.uk/content/archive/7284.html

But I can't find his company. Anyone know how to buy one of these?

what's the point in buying one, if you [legally] can't use it?

On Fri, 19 Dec 2003 15:50:05 +0100 (CET), Nomen Nescio
wrote:

According to an article in the Register, Anil Vora has invented a
handheld phone jammer for about £30.

The article is four years old, £18.00 was mentioned and the product
never appeared - at least not in the UK - where its use would be
illegal.

--
Hiram Hackenbacker

"Nomen Nescio" wrote in message
...
According to an article in the Register, Anil Vora has invented a
handheld phone jammer for about £30.
Why so you can haunt or Stalk alan erskine even more?

On Fri, 19 Dec 2003 14:55:55 -0000, "NorwichLad"
wrote:

According to an article in the Register, Anil Vora has invented a
handheld phone jammer for about £30.

http://www.theregister.co.uk/content/archive/7284.html

But I can't find his company. Anyone know how to buy one of these?

what's the point in buying one, if you [legally] can't use it?

I am not sure that would stop me getting one and using in on my daily
commute to Waterloo (in the non-mobiles car).

--
Hiram Hackenbacker

--
For email please use:
http://www.davetopping.com/usenet.
"Jaime" wrote in message
...


See
http://www.globalgadgetuk.com/cell%2...%20jammers.htm

"Hiram Hackenbacker" wrote in message
...
On Fri, 19 Dec 2003 14:55:55 -0000, "NorwichLad"
wrote:

According to an article in the Register, Anil Vora has invented a
handheld phone jammer for about £30.

http://www.theregister.co.uk/content/archive/7284.html

But I can't find his company. Anyone know how to buy one of these?

what's the point in buying one, if you [legally] can't use it?

I am not sure that would stop me getting one and using in on my daily
commute to Waterloo (in the non-mobiles car).


Non Mobiles car? Didnt know swt had any of them.

Jaime

"Nomen Nescio" wrote in message
...
According to an article in the Register, Anil Vora has invented a
handheld phone jammer for about £30.

http://www.theregister.co.uk/content/archive/7284.html

But I can't find his company. Anyone know how to buy one of these?

I believe that jamming mobile phone frequencies can result in a prison
sentence.
Mike.



---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.552 / Virus Database: 344 - Release Date: 15-Dec-2003

On Fri, 19 Dec 2003 15:50:05 +0100 (CET), Nomen Nescio
wrote:

According to an article in the Register, Anil Vora has invented a
handheld phone jammer for about £30.

http://www.theregister.co.uk/content/archive/7284.html

But I can't find his company. Anyone know how to buy one of these?



It is illegal in the U.S.

http://wireless.fcc.gov/services/cel...ngjamming.html




--
Hal
Amateur Radio Station K1HK

On Fri, 19 Dec 2003 17:57:28 +0100 (CET), Tarapia Tapioco
wrote:

I want to build a mobile phone jammer

* short range (not more than 5 yds)
* handheld, small
* battery powered

so that when I'm on the bus/train and some idiot start loudly talking
about his business, I can press a button and cause just enough
interference to disconnect him mysteriously.

It would be better if it had some directionality but not too much. I
don't want to aim it at someone but it would be nice to be able to
disconnect the loud phone user in front of me without affecting the
text messager behind me.

Can anyone point me in the right direction for designing this?
http://gbppr.dyndns.org/PROJ/mil/celljam/

The site gets really slow at times. Suggest you save the schematics
so you won't have problems if the site goes down.



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

On Fri, 19 Dec 2003 17:52:17 GMT, Hal wrote:

On Fri, 19 Dec 2003 15:50:05 +0100 (CET), Nomen Nescio
wrote:

According to an article in the Register, Anil Vora has invented a
handheld phone jammer for about £30.

http://www.theregister.co.uk/content/archive/7284.html

But I can't find his company. Anyone know how to buy one of these?



It is illegal in the U.S.

http://wireless.fcc.gov/services/cel...ngjamming.html

So is corporate price fixing, political bribes, and speeding; YOUR
POINT BEING?


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Tarapia Tapioco wrote:

I want to build a mobile phone jammer

* short range (not more than 5 yds)
* handheld, small
* battery powered

so that when I'm on the bus/train and some idiot start loudly talking
about his business, I can press a button and cause just enough
interference to disconnect him mysteriously.

What's the problem? If someone annoys me too much with a phone, I just
offer to jam it somewhere. Manually. ;-)

--
Paul Hovnanian
note to spammers: a Washington State resident
------------------------------------------------------------------
On a clear disk, you can seek forever.

default wrote:

On Fri, 19 Dec 2003 17:57:28 +0100 (CET), Tarapia Tapioco
wrote:

I want to build a mobile phone jammer

* short range (not more than 5 yds)
* handheld, small
* battery powered

so that when I'm on the bus/train and some idiot start loudly talking
about his business, I can press a button and cause just enough
interference to disconnect him mysteriously.

It would be better if it had some directionality but not too much. I
don't want to aim it at someone but it would be nice to be able to
disconnect the loud phone user in front of me without affecting the
text messager behind me.

Can anyone point me in the right direction for designing this?
http://gbppr.dyndns.org/PROJ/mil/celljam/

Whenever I try to hit that site i get:

Forbidden
You don't have permission to access /PROJ/mil/celljam on this server.

What's the story?


--
Peter E. Lowrie
----------------------------------------------------------

futureworlds wrote:

Even if they complained, would the police or even the UK
equivalent of the FCC be interested in expending the resources to
track down and prosecute a nut with a few mW transmitter?

Oh, yeah. Big time.

Operating a low-power illegal "normal" transmitter (like an unlicensed
CB set) is one thing - a minor offence under Part I (s.1) of the
Wireless Telegraphy Act; they'll just get the kit seized, and a Police
caution. Perhaps a small fine if it's worth a prosecution. Maybe even
a suspended jail sentence if it was shown to be interfering with
licensed equipment (by accident).

Deliberate jamming, on the other hand, is a Part II (s.13) offence, and
a whole different order of magnitude. The Radiocommunications Agency
(www.radio.gov.uk) will rain Hellfire on offenders: expect a jail term
and/or (probably 'and') a stiff fine. And seizure of anything, not just
txing equipment, that could be argued to be relevant to the offence.


Jon
--
SPAM BLOCK IN USE! Replace 'deadspam' with 'green-lines' to reply in email.
Want a free solution to email spam? Try http://www.deadspam.com/
(Declaration of interest: I own/run the domain.)

there was talk that bush was planning to be party to some mobile phone
jamming action during his visit to blighty.
how would that stand?

oo.
"Mike GW8IJT" wrote in message
...
"Nomen Nescio" wrote in message
...
According to an article in the Register, Anil Vora has invented a
handheld phone jammer for about £30.

http://www.theregister.co.uk/content/archive/7284.html

But I can't find his company. Anyone know how to buy one of these?

I believe that jamming mobile phone frequencies can result in a prison
sentence.
Mike.



---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.552 / Virus Database: 344 - Release Date: 15-Dec-2003

On Fri, 19 Dec 2003 21:28:16 -0000, "oo" wrote:

there was talk that bush was planning to be party to some mobile phone
jamming action during his visit to blighty.

No, he wanted the networks switched off.


--

Iain
the out-of-date hairydog guide to mobile phones
http://www.hairydog.co.uk/cell1.html
Browse now while stocks last!

On Fri, 19 Dec 2003 12:22:22 -0800, Paul Hovnanian P.E. wrote:

Tarapia Tapioco wrote:

I want to build a mobile phone jammer

* short range (not more than 5 yds)
* handheld, small
* battery powered

so that when I'm on the bus/train and some idiot start loudly talking
about his business, I can press a button and cause just enough
interference to disconnect him mysteriously.

What's the problem? If someone annoys me too much with a phone, I just
offer to jam it somewhere. Manually. ;-)

When someone annoys me by yakking on a cell phone in a restaurant, meeting
etc., I just join right in the conversation "Sure thing Bill. Friday's
great. Just don't bring that whiny annoying wife of yours..." etc.
I get some priceless looks.

Bob

isnt that interfering with licenced bandwith?

oo
wrote in message
...
On Fri, 19 Dec 2003 21:28:16 -0000, "oo" wrote:

there was talk that bush was planning to be party to some mobile phone
jamming action during his visit to blighty.

No, he wanted the networks switched off.


--

Iain
the out-of-date hairydog guide to mobile phones
http://www.hairydog.co.uk/cell1.html
Browse now while stocks last!

"oo" wrote:

wrote in message
...
On Fri, 19 Dec 2003 21:28:16 -0000, "oo" wrote:

there was talk that bush was planning to be party to some mobile phone
jamming action during his visit to blighty.

No, he wanted the networks switched off.

isnt that interfering with licenced bandwith?

Sorry, I think I must have woken up. For the past decade or three, I've
been living in a dreamworld where the US ignores any international or
national laws it considers inconvenient.

Jon
--
SPAM BLOCK IN USE! Replace 'deadspam' with 'green-lines' to reply in email.
Want a free solution to email spam? Try http://www.deadspam.com/
(Declaration of interest: I own/run the domain.)

"Jon S Green" wrote:
futureworlds wrote:

Even if they complained, would the police or even the UK
equivalent of the FCC be interested in expending the resources to
track down and prosecute a nut with a few mW transmitter?

Oh, yeah. Big time.

Operating a low-power illegal "normal" transmitter (like an unlicensed
CB set) is one thing - a minor offence under Part I (s.1) of the
Wireless Telegraphy Act; they'll just get the kit seized, and a Police
caution. Perhaps a small fine if it's worth a prosecution. Maybe even
a suspended jail sentence if it was shown to be interfering with
licensed equipment (by accident).

Speaking from personal experience many years ago this just didn't happen.

Yes the DTI did go round in their detector vans when the problem got out
of hand. Found out the people using, say, 500W 27MHz amps and hi-gain
antennas with SSB rigs.

Then normally told them to stop using it & get rid of it. Took gear off
them if it was causing interference to phones/TVs/radio.

I've never heard anyone get a fine. Never heard police involved. Police
didn't want to know if people reported severe interference to them.
Suspended jail sentence? Never heard of any.

Deliberate jamming, on the other hand, is a Part II (s.13) offence, and
a whole different order of magnitude. The Radiocommunications Agency
(www.radio.gov.uk) will rain Hellfire on offenders: expect a jail term
and/or (probably 'and') a stiff fine. And seizure of anything, not just
txing equipment, that could be argued to be relevant to the offence.

Have you ever seen this happen? Seisure I can see, but nothing else. The
RA/DTI are/were a bunch of lazy sods :-)



frag

Hello,

The RIS tend to go out at nights and weekends and can take months finding a
station. It depends on the amount of overtime.

"Richard Wood" wrote in message
...
"Jon S Green" wrote:
futureworlds wrote:

Even if they complained, would the police or even the UK
equivalent of the FCC be interested in expending the resources to
track down and prosecute a nut with a few mW transmitter?

Oh, yeah. Big time.

Operating a low-power illegal "normal" transmitter (like an unlicensed
CB set) is one thing - a minor offence under Part I (s.1) of the
Wireless Telegraphy Act; they'll just get the kit seized, and a Police
caution. Perhaps a small fine if it's worth a prosecution. Maybe even
a suspended jail sentence if it was shown to be interfering with
licensed equipment (by accident).

Speaking from personal experience many years ago this just didn't happen.

Yes the DTI did go round in their detector vans when the problem got out
of hand. Found out the people using, say, 500W 27MHz amps and hi-gain
antennas with SSB rigs.

Then normally told them to stop using it & get rid of it. Took gear off
them if it was causing interference to phones/TVs/radio.

I've never heard anyone get a fine. Never heard police involved. Police
didn't want to know if people reported severe interference to them.
Suspended jail sentence? Never heard of any.

Deliberate jamming, on the other hand, is a Part II (s.13) offence, and
a whole different order of magnitude. The Radiocommunications Agency
(www.radio.gov.uk) will rain Hellfire on offenders: expect a jail term
and/or (probably 'and') a stiff fine. And seizure of anything, not just
txing equipment, that could be argued to be relevant to the offence.

Have you ever seen this happen? Seisure I can see, but nothing else. The
RA/DTI are/were a bunch of lazy sods :-)



frag

On Fri, 19 Dec 2003 21:44:04 GMT, Bob Stephens
wrote:

On Fri, 19 Dec 2003 12:22:22 -0800, Paul Hovnanian P.E. wrote:

Tarapia Tapioco wrote:

I want to build a mobile phone jammer

* short range (not more than 5 yds)
* handheld, small
* battery powered

so that when I'm on the bus/train and some idiot start loudly talking
about his business, I can press a button and cause just enough
interference to disconnect him mysteriously.

What's the problem? If someone annoys me too much with a phone, I just
offer to jam it somewhere. Manually. ;-)

When someone annoys me by yakking on a cell phone in a restaurant, meeting
etc., I just join right in the conversation "Sure thing Bill. Friday's
great. Just don't bring that whiny annoying wife of yours..." etc.
I get some priceless looks.

Bob
Hey that's pretty good - worth a try.

Now, what is your technique for getting the woman on the road in the
SUV who is ambivalent about which lane she intends to use?


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

snip
Can anyone point me in the right direction for designing this?
http://gbppr.dyndns.org/PROJ/mil/celljam/

Whenever I try to hit that site i get:

Forbidden
You don't have permission to access /PROJ/mil/celljam on this server.

What's the story?
I know the site is slow - sometimes there's just a blip every few
seconds on the download meter - othertimes it works normally.

Can you hear me now? No. Good.

Devices to jam the downlink frequencies on various cellular telephone systems. Prevents the
cellular phone user from sending or receiving phone calls within the small jam
radius. Advanced electronic and RF engineering technical skills will be required.
http://gbppr.dyndns.org/PROJ/mil/cel...l_jammer-3.png
http://gbppr.dyndns.org/PROJ/mil/celljam/pcs_jammer.png

Links to a couple of schematics on the site.

Try the main site http://gbppr.dyndns.org/
and follow the link to projects then scroll down to cell phone jammers

Have any special software running? I can access it with web washer
running, set for maximum privacy - no cookies, no web bugs, no
refferer. I'm in the US


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

On Sat, 20 Dec 2003 07:46:24 -0000, Jon
wrote:

If Mr bush said "would you mind turning
off your network for a few hours" and the network said "yeah, OK"

I think you'll find that what would have happened is that Mr Bush asks
them to turn the networks off, and the networks respond "Off? ****
off!"


--

Iain
the out-of-date hairydog guide to mobile phones
http://www.hairydog.co.uk/cell1.html
Browse now while stocks last!

wrote in message
...
On Sat, 20 Dec 2003 07:46:24 -0000, Jon
wrote:

If Mr bush said "would you mind turning
off your network for a few hours" and the network said "yeah, OK"

I think you'll find that what would have happened is that Mr Bush asks
them to turn the networks off, and the networks respond "Off? ****
off!"
Iain

Didn't Tony give himself powers to turn off GSM networks after the fuel strike.

Steve Terry

On Sat, 20 Dec 2003 20:18:07 -0000, "Steve Terry"
wrote:

Didn't Tony give himself powers to turn off GSM networks after the fuel strike.

There have been those powers for a very long time.

--

Iain
the out-of-date hairydog guide to mobile phones
http://www.hairydog.co.uk/cell1.html
Browse now while stocks last!

default wrote:
snip
Whenever I try to hit that site i get:
Forbidden
You don't have permission to access /PROJ/mil/celljam on this server.
What's the story?
Devices to jam the downlink frequencies on various cellular telephone
systems. Prevents the
cellular phone user from sending or receiving phone calls within the
small jam
radius. Advanced electronic and RF engineering technical skills will
be required.
http://gbppr.dyndns.org/PROJ/mil/cel...l_jammer-3.png
http://gbppr.dyndns.org/PROJ/mil/celljam/pcs_jammer.png

Links to a couple of schematics on the site.

Try the main site http://gbppr.dyndns.org/
and follow the link to projects then scroll down to cell phone jammers

Have any special software running? I can access it with web washer
running, set for maximum privacy - no cookies, no web bugs, no
refferer. I'm in the US

It still wont let me in, i have a feeling it's being blocked by internal
affairs. Howsabout emailing the png files to me...that'd be appreciated.


--
Peter E. Lowrie

----------------------------------------------------------

default wrote:

snip
Can anyone point me in the right direction for designing this?
http://gbppr.dyndns.org/PROJ/mil/celljam/

Whenever I try to hit that site i get:

Forbidden
You don't have permission to access /PROJ/mil/celljam on this server.

What's the story?
I know the site is slow - sometimes there's just a blip every few
seconds on the download meter - othertimes it works normally.

Can you hear me now? No. Good.

Devices to jam the downlink frequencies on various cellular telephone
systems. Prevents the
cellular phone user from sending or receiving phone calls within the
small jam
radius. Advanced electronic and RF engineering technical skills will
be required.
http://gbppr.dyndns.org/PROJ/mil/cel...l_jammer-3.png
http://gbppr.dyndns.org/PROJ/mil/celljam/pcs_jammer.png

Links to a couple of schematics on the site.

Try the main site http://gbppr.dyndns.org/
and follow the link to projects then scroll down to cell phone jammers

Have any special software running? I can access it with web washer
running, set for maximum privacy - no cookies, no web bugs, no
refferer. I'm in the US


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Another idea would be to post the images onto
alt.binaries.schematics.electronic

--
Peter E. Lowrie
----------------------------------------------------------

Tarapia Tapioco wrote in message ux.it...
I want to build a mobile phone jammer

* short range (not more than 5 yds)
* handheld, small
* battery powered

so that when I'm on the bus/train and some idiot start loudly talking
about his business, I can press a button and cause just enough
interference to disconnect him mysteriously.

It would be better if it had some directionality but not too much. I
don't want to aim it at someone but it would be nice to be able to
disconnect the loud phone user in front of me without affecting the
text messager behind me.

Can anyone point me in the right direction for designing this?

I'll assume that you realize doing something like this is a
non-trivial violation of federal law. Last time I checked, malicous
interferrence with federally licensed communications could earn one a
$10,000 fine, 10-years in prison, or both.

Cell phone jamming now already takes place in numerous facilities like
hospitals, theatres, restaurants, and other venues (quite thankfully),
but there it's confined to private property. Even then, it will likely
be shown by the ACLU or some other leftist group to be an encroachment
on existing communications law.

Harry C.

On 20 Dec 2003 16:40:40 -0800, (Harry Conover) wrote:

[snip]
Cell phone jamming now already takes place in numerous facilities like
hospitals, theatres, restaurants, and other venues (quite thankfully),
but there it's confined to private property. Even then, it will likely
be shown by the ACLU or some other leftist group to be an encroachment
on existing communications law.

Harry C.

I think there's already been a court determination that *jamming*,
even on private property is illegal; but Faraday screening is legal.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Sat, 20 Dec 2003 08:54:16 -0500, default wrote:

On Fri, 19 Dec 2003 21:44:04 GMT, Bob Stephens
wrote:

On Fri, 19 Dec 2003 12:22:22 -0800, Paul Hovnanian P.E. wrote:

Tarapia Tapioco wrote:

I want to build a mobile phone jammer

* short range (not more than 5 yds)
* handheld, small
* battery powered

so that when I'm on the bus/train and some idiot start loudly talking
about his business, I can press a button and cause just enough
interference to disconnect him mysteriously.

What's the problem? If someone annoys me too much with a phone, I just
offer to jam it somewhere. Manually. ;-)

When someone annoys me by yakking on a cell phone in a restaurant, meeting
etc., I just join right in the conversation "Sure thing Bill. Friday's
great. Just don't bring that whiny annoying wife of yours..." etc.
I get some priceless looks.

Bob
Hey that's pretty good - worth a try.

Now, what is your technique for getting the woman on the road in the
SUV who is ambivalent about which lane she intends to use?


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Well I live and drive in Los Angeles.... I could probably handle lane
ambivalence. It would be a step in the right direction for the SUV set out
here. What we have approximates Brownian motion!

-Bob

"DaveC" wrote in message
al.net...
On Tue, 23 Dec 2003 10:45:30 -0800, starwars wrote
(in message ux.net):

"Ken Taylor" wrote:


"Paul Burridge" wrote in message
...
On 21 Dec 2003 13:11:20 -0000, er (Italy
Anonymous Remailer) wrote:

Well, the OP did say he wanted a maximum range of 5 yds inside a bus.
Anyone know what sort of wattage that works out to? I suspect we're
talking about a few mW.

Or less, even. What power level do those car lock r/c key fob thingies
work at? That ought to give some sort of indication.


Why would it? The applications are totally different.

I agree. The car lock remote uses infrared (I think) and transmits a
very specific signal that the car receiver detects.

The jammer would use cellphone frequencies (around 9GHz and similar
bands, I think) and would need to transmit--I think--white noise
across the target band, strong enough to drown out the signal the
phone is already receiving.

No. The car alarm/autolocking remote controls use RF, not IR. Simply arm
or
disarm your car alarm (you *do* have one, don't you?) from inside your
home
to prove this.

Those owners who "point" the remote control at the car, haven't a clue how
they work...
--
DaveC

I agree about the RF in the car locks, and, also, cell phones aren't (yet)
at 9GHz(!). 900/1800/2400MHz generally. However they are pretty robust from
an RFI perspective (dependant on cell system). The key lock would probably
be a lot easier to jam.

Anyway, all this begs the question - who the f**k do these people who want
to jam/ban cell phones on buses and restaurants think they are? If I'm
talking to the person next to me, is that okay? If I'm still talking to
them, but over the phone, is that still okay? (Dumb maybe, but okay?).
What's the difference whether I'm talking to a person in the flesh or via a
piece of plastic and metal. At the cinema or theatre - sure. But who the
hell is making these rulings about what's socially acceptable?

Ken

I read in sci.electronics.design that Ken Taylor
wrote (in ) about 'mobile
(cell) phone jamming', on Wed, 24 Dec 2003:

What's the difference whether I'm talking to a person in the flesh or via a
piece of plastic and metal.

It's not the phoning that's annoying, it's the loud voice, which is
quite unnecessary but we've got used to it through using ordinary
phones. Ordinary phones have 'sidetone' anyway - you hear your own voice
in the earpiece and that helps to control your own voice level. Mobile
phones DON'T HAVE SIDETONE, which is a bit of a surprise when you first
realise it. WHY they don't have it, I don't know; maybe the small
dimensions mean that a usable level of sidetone results in acoustic
feedback. But a mobile with sidetone might eliminate the annoying VOICE
LEVEL.
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!

On Tue, 23 Dec 2003 21:30:57 +0000, John Woodgate
wrote:

I read in sci.electronics.design that Ken Taylor
wrote (in ) about 'mobile
(cell) phone jamming', on Wed, 24 Dec 2003:

What's the difference whether I'm talking to a person in the flesh or via a
piece of plastic and metal.

It's not the phoning that's annoying, it's the loud voice, which is
quite unnecessary but we've got used to it through using ordinary
phones. Ordinary phones have 'sidetone' anyway - you hear your own voice
in the earpiece and that helps to control your own voice level. Mobile
phones DON'T HAVE SIDETONE, which is a bit of a surprise when you first
realise it. WHY they don't have it, I don't know; maybe the small
dimensions mean that a usable level of sidetone results in acoustic
feedback. But a mobile with sidetone might eliminate the annoying VOICE
LEVEL.

Agreed. That's the nub of it. And there are still a lot of folks
around who seem to think if the person they're calling is a long way
away, they need to shout even louder!

--

"I expect history will be kind to me, since I intend to write it."
- Winston Churchill

"Paul Burridge" wrote in message
...
On Tue, 23 Dec 2003 21:30:57 +0000, John Woodgate
wrote:

I read in sci.electronics.design that Ken Taylor
wrote (in ) about 'mobile
(cell) phone jamming', on Wed, 24 Dec 2003:

What's the difference whether I'm talking to a person in the flesh or
via a
piece of plastic and metal.

It's not the phoning that's annoying, it's the loud voice, which is
quite unnecessary but we've got used to it through using ordinary
phones. Ordinary phones have 'sidetone' anyway - you hear your own voice
in the earpiece and that helps to control your own voice level. Mobile
phones DON'T HAVE SIDETONE, which is a bit of a surprise when you first
realise it. WHY they don't have it, I don't know; maybe the small
dimensions mean that a usable level of sidetone results in acoustic
feedback. But a mobile with sidetone might eliminate the annoying VOICE
LEVEL.

Agreed. That's the nub of it. And there are still a lot of folks
around who seem to think if the person they're calling is a long way
away, they need to shout even louder!

Aint that the truth! I'll go along with that argument - discretion is such a
poorly rated virtue.

Ken

"Ken Taylor" wrote in message
...
"Paul Burridge" wrote in message
...
On Tue, 23 Dec 2003 21:30:57 +0000, John Woodgate
wrote:

I read in sci.electronics.design that Ken Taylor
wrote (in ) about 'mobile
(cell) phone jamming', on Wed, 24 Dec 2003:

What's the difference whether I'm talking to a person in the flesh or
via a
piece of plastic and metal.

It's not the phoning that's annoying, it's the loud voice, which is
quite unnecessary but we've got used to it through using ordinary
phones. Ordinary phones have 'sidetone' anyway - you hear your own
voice
in the earpiece and that helps to control your own voice level. Mobile
phones DON'T HAVE SIDETONE, which is a bit of a surprise when you first
realise it. WHY they don't have it, I don't know; maybe the small
dimensions mean that a usable level of sidetone results in acoustic
feedback. But a mobile with sidetone might eliminate the annoying VOICE
LEVEL.

Agreed. That's the nub of it. And there are still a lot of folks
around who seem to think if the person they're calling is a long way
away, they need to shout even louder!

Aint that the truth! I'll go along with that argument - discretion is such
a
poorly rated virtue.


And, for some reason, people on a phone forget they are in a crowd.
Nothing like being in a public venue and having someone shouting into
their phone, discusing someone stool sample (true story).

"George Orwell" wrote in message
...
"Gordon Brown" . wrote:

"Steve Terry" wrote in message
...

You mix 45MHz with the phones own TX signal, from any phone nearby.
Then retransmitting itself up 45MHz into the phones receiver.

Whatever channel the phone is on, it's always a precise 45MHz
diference

Without the phones transmit signal all the jammer puts out is it's
45MHz
osc

What so difficult to understand ??

The difficult bit is adding the time delay so the phones TX time slots
overlap
it's own RX time slots, otherwise the phone simply won't hear itself,
feedback, and stop working.

Ah, I see, you mean a broadband jammer (otherwise it will not cope with
two
phones transmitting on different channels). For some reason I was
assuming
that it was some elaborate narrow band jamming device. Why not just
transmit
a burst of white noise at 950Mhz with a 45MHz BW?

That's what I was thinking. This would be a lot simpler than having to
detect a specific signal, modulate it by 45MHz an retransmit it.

Would the white noise across the right frequency band confuse the
phone enough to disconnnect or garble the call?


Probably not. Particularly a CDMA system, unless you put out so much power
that you were obvious to the crowd - the car battery, being up against a
wall, being cavity probed by the FBI........

Ken

"George Orwell" wrote in message
...
"Gordon Brown" . wrote:
That's what I was thinking. This would be a lot simpler than having to
detect a specific signal, modulate it by 45MHz an retransmit it.

Would the white noise across the right frequency band confuse the
phone enough to disconnnect or garble the call?

I am no RF engineer, but IIRC, building a broadband transmitter
intentionally is not that simple. Also the noise will have to be above the
signal from the base station transmitter (say 50W transmitter?). I wonder if
it would not be easier to jam the uplink signal as this would only require
the jammer to transmit in the same order of power as the mobile.

"George Orwell" wrote in message
...
"Gordon Brown" . wrote:
"Steve Terry" wrote in message
...
snip
Ah, I see, you mean a broadband jammer (otherwise it will not cope with two
phones transmitting on different channels). For some reason I was assuming
that it was some elaborate narrow band jamming device. Why not just transmit
a burst of white noise at 950Mhz with a 45MHz BW?

That's what I was thinking. This would be a lot simpler than having to
detect a specific signal, modulate it by 45MHz an retransmit it.

A broad UHF input 45MHz mixer osc with broad UHF output is very simple to make

Would the white noise across the right frequency band confuse the
phone enough to disconnnect or garble the call?

A broadband UHF white noise jammer would have to transmit very much more power
to have an effect

The whole point of the phone operating on a 45MHz split with odd phased
time slots is so the phones RX doesn't hear it's TX.
Upset any part of that cycle with a relatively low signal, and the phone stops
working.

Steve Terry

"Steve Terry" wrote in message
...
The whole point of the phone operating on a 45MHz split with odd phased
time slots is so the phones RX doesn't hear it's TX.
Upset any part of that cycle with a relatively low signal, and the phone
stops
working.

So what sort of delay would be necessary and to what tolerance?

"Gordon Brown" . wrote in message
...
"Steve Terry" wrote in message
...
The whole point of the phone operating on a 45MHz split with odd phased
time slots is so the phones RX doesn't hear it's TX.
Upset any part of that cycle with a relatively low signal, and the phone
stops
working.

So what sort of delay would be necessary and to what tolerance?

A few microsecs ?
I would guess interfere with as little as 20% of the slots to stop the phone
working

If there is already a random element in the slots maybe just letting the
phones RX see it's TX with a nearby 45MHz mixer osc could be enough ?

Steve Terry