Searching \ for '[OT] Cell phone blocking' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/index.htm?key=cell+phone+blocking
Search entire site for: 'Cell phone blocking'.

Exact match. Not showing close matches.
PICList Thread
'[OT] Cell phone blocking'
2000\03\16@161605 by gclord

picon face
I just heard from a guy that some restaurants in Japan have installed
devices that block cell phone calls to prevent users from disturbing other
patrons.

Any idea how that would work?

Thoughts on usefulness in USA? Legality of preventing cell phone use in
surrounding cars while I'm driving on the freeway? <GRIN> using the
restroom? <VBG>

---
James Newton spam_OUTjamesnewtonTakeThisOuTspamgeocities.com 1-619-652-0593
http://techref.massmind.org NEW! FINALLY A REAL NAME!
Members can add private/public comments/pages ($0 TANSTAAFL web hosting)

2000\03\16@165757 by Rob Brzykcy

picon face
I have already looked into this.. I severly doubt that it will be feasible
to do so in the US.
Its a bit easier to step on toes in the name of the "public good" in Japan.
The legalities and lawsuits that could arise from such a device are
astronomical.

I *think* that using a DSP, you could look for emanation of radio waves on a
certain freq in the vicinity, then, immediately thereafter send a jamming
signal on the same freq until the person gives up and turns the phone off.

I think its much easier and perhaps cheaper to hire a "phone bouncer" to
tell ppl to leave the things in the car..

I say "bouncer" because I once saw a doctor get extremely irate and throw
(!?!) his phone at the hostess who asked that he leave it in the car. I
believe someone much bigger than the ppl who typically put up such a fuss
would deter these hothead types. I personally really wanted to send him out
on a stretcher with his phone jammed permanently in his ear.  (or add an R
to the beginning of the word for colorfulness) and this got me thinking
about the whole jamming idea.

If you can figure out a way to do it, Ill gladly be an area rep for the sale
and installation! ;)


Rob

{Original Message removed}

2000\03\16@173122 by David VanHorn

flavicon
face
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1


>Thoughts on usefulness in USA? Legality of preventing cell phone use in
>surrounding cars while I'm driving on the freeway? <GRIN> using the
>restroom? <VBG>

It's a nice way to insure a stay in a hotel where cellphones are not
allowed, that's for sure.
Are you looking for a long vacation?

-----BEGIN PGP SIGNATURE-----
Version: PGPfreeware 6.5.2 for non-commercial use <http://www.pgp.com>

iQA/AwUBONGKboFlGDz1l6VWEQLc5wCfT3fV18267lVPUOyr3F61AlFJvksAn0SS
0EycNOg4+tmhr8bPld8EVCL2
=Uoan
-----END PGP SIGNATURE-----

2000\03\16@174810 by picxpert

picon face
An easier way to protect a single room from cell phones is to put copper
mesh in the walls - it will block radio waves, I beleive, if you ground it.

-Randy Glenn
.....PICxpertKILLspamspam@spam@techie.com - http://i.am/PICxpert

Ineptitude is a sure indicator of intellect.
===========
To unsubscribe, send a message containing the text "unsubscribe PICLIST" to
LISTSERVspamKILLspamMITVMA.MIT.EDU

{Original Message removed}

2000\03\16@175435 by Dmitry Kiryashov

flavicon
face
That's correct. Any good conducting shielding
connected to ground (earth)
will strongly reduce radio waves from both sides.

WBR Dmitry.

Randy Glenn wrote:
>
> An easier way to protect a single room from cell phones is to put copper
> mesh in the walls - it will block radio waves, I beleive, if you ground it.
>
> -Randy Glenn
> .....PICxpertKILLspamspam.....techie.com - http://i.am/PICxpert

2000\03\16@181602 by Barry King

flavicon
face
> I just heard from a guy that some restaurants in Japan have installed
> devices that block cell phone calls to prevent users from disturbing other
> patrons.
>
> Any idea how that would work?

I don't think it would be technically difficult.  All you would have
to do is have a jammer transmitter on the initial paging channel for
each carrier.  (two transmitters would suffice in most areas)  Then
the phone couldn't hear any paging (i.e. ringing) from the cell site.

I doubt you could liscence this commercially. This is a liscensed
band, and all the equipment is registered with FCC, and they might
take a dim view- do you really WANT to prevent people from dialing
911?  If the FCC wanted to let you do it, it would not be technically
hard...

------------
Barry King, KA1NLH
NRG Systems "Measuring the Wind's Energy"
http://www.nrgsystems.com
Check out the accumulated (PIC) wisdom of the ages at:
PIC/PICList FAQ: http://www.piclist.org

2000\03\16@182206 by jamesnewton

face picon face
Connect through a tank circuit (LC) to block only certain frequencies?

---
James Newton EraseMEjamesnewtonspam_OUTspamTakeThisOuTgeocities.com 1-619-652-0593
http://techref.massmind.org NEW! FINALLY A REAL NAME!
Members can add private/public comments/pages ($0 TANSTAAFL web hosting)


{Original Message removed}

2000\03\16@184925 by Harold M Hallikainen

picon face
On Thu, 16 Mar 2000 13:11:53 -0800 James Newton <eplus1spamspam_OUTSAN.RR.COM>
writes:
{Quote hidden}

DA 99-2150 Released: October 12, 1999

Office of Engineering and Technology and Compliance and Information
Bureau Warn Against the Manufacture, Importation, Marketing or Operation
of Transmitters Designed to Prevent or Otherwise Interfere with Cellular
Radio Communications

The Commission's Office of Engineering and Technology (OET) and
Compliance and Information Bureau (CIB) have received several inquiries
concerning the use of transmitters designed to prevent or jam the
operation of cellular telephones in hospitals, theaters and other
locations. The Communications Act of 1934, as amended, and the
Commission's Rules do not permit these devices to be manufactured,
imported, marketed or operated within the United States.

Section 302(b) of the Communications Act, 47 USC 302(b), prohibits the
manufacture, importation, sale, offer for sale, or use of devices that
fail to comply with the regulations promulgated pursuant to this section.
Similar prohibitions are contained in the Commission's rules, e.g., 47
CFR Sections 2.803, 2.1203, and 22.377. In addition, in accordance with
Section 301 of the Communications Act, 47 USC 301, persons operating or
using radio transmitters must be licensed or authorized under the
Commission's rules. There are no provisions in the FCC's rules that
permit the operation of any device intended to interfere with cellular
communications. Further, Section 333 of the Communications Act, 47 USC
333, prohibits any person from willfully or maliciously interfering with
the radio communications of any station licensed or authorized under the
Communications Act or operated by the U.S. Government.

Based on the above, the operation of transmitters designed to jam
cellular communications is a violation of 47 USC 301, 302(b), and 333.
The manufacture, importation, sale or offer for sale, including
advertising, of such transmitters is a violation of 47 USC 302(b).
Parties in violations of these provisions may be subject to the penalties
contained within 47 USC 501-510. Fines for a first offense can range as
high as $ 11,000 for each violation or imprisonment for up to one year.
The equipment can also be seized and forfeited to the U.S. Government.

OET and CIB wish to emphasize that the above regulations apply to all
transmitters that are designed to cause interference to, or prevent the
operation of, other radio communication systems.

Questions regarding this Public Notice may be directed to the
Commission's National Call Center at 1-888-CALL FCC (1-888-225-5322).



Harold


FCC Rules Online at http://hallikainen.com/FccRules
Lighting control for theatre and television at http://www.dovesystems.com

________________________________________________________________
YOU'RE PAYING TOO MUCH FOR THE INTERNET!
Juno now offers FREE Internet Access!
Try it today - there's no risk!  For your FREE software, visit:
dl.http://www.juno.com/get/tagj.

2000\03\16@185125 by Rob Brzykcy

picon face
As for the copper mesh, this would be barely sufficient. We have glass that
has mesh between the laminated layers at work (someones idea of overkill)
and the whole building is fully encased in mesh/steel, and cellphones still
work, as do pagers, radios and tv. Needless to say, we still ended up having
to buy metal closets to test rf gear in, so it ended up being a good waste
of alot of money.

Theoretically, the mesh is good, but in actual use, its decent at best.

It will cost so much and work so inadequately as not to be worth it.

Rob

2000\03\16@185955 by Quitt, Walter

flavicon
face
If it were fine mesh and all bonded together and grounded
it might work.  Go look at things called:
Screen Rooms
They are basically a big cube of very fine copper mesh,
soldered together at the seams with the doors having
mesh RF gaskets.
Such rooms can be seen in military installations,
communications repair shops and places where they
do CE or other emmissions testing.

Been there and done that, an RF tight room is a hard thing to make.

-Walt

{Original Message removed}

2000\03\16@194052 by David VanHorn

flavicon
face
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1


>I doubt you could liscence this commercially. This is a liscensed
>band, and all the equipment is registered with FCC, and they might
>take a dim view- do you really WANT to prevent people from dialing
>911?  If the FCC wanted to let you do it, it would not be technically
>hard...


FROM A HAM????
You very well ought to know that deliberate jamming is illegal as all hell.


-----BEGIN PGP SIGNATURE-----
Version: PGPfreeware 6.5.2 for non-commercial use <http://www.pgp.com>

iQA/AwUBONGolIFlGDz1l6VWEQL8ggCdGMaudxRpGVoDlaf37i7H/mKq/UoAoIEU
1uQE3YLfYbGSLjNzl3PFXQCb
=+kfy
-----END PGP SIGNATURE-----

2000\03\16@194808 by Daniel Hart

flavicon
face
Just for fun.
Suppose that you had about 10 phones connected to wall power and turned on. The base station would
have trouble pulling the other phones in the room in, so it would turn up the handset power. The
plugged in phone could handle the power fine, but the other handsets would soon go dead. Noticing
the low battery signal the patrons would turn off their phones. Japan uses CDMA which is shared
carrier, power regulated, and frequently polled by the basestation. The polling is part of the
infrastructure and is free. GSM and our old fashioned TDM phones would not be effected. Not a mobile
solution.
Dan ;-)

"Quitt, Walter" wrote:

{Quote hidden}

> {Original Message removed}

2000\03\16@202157 by Robert Rolf

picon face
Harold M Hallikainen wrote:
>
> On Thu, 16 Mar 2000 13:11:53 -0800 James Newton <KILLspameplus1KILLspamspamSAN.RR.COM>
> writes:
> > I just heard from a guy that some restaurants in Japan have installed
> > devices that block cell phone calls to prevent users from disturbing
> > other
> > patrons.
> >
> > Any idea how that would work?

This URL has such a commercial product:
http://www.netline.co.il/new/c-guard.htm

The device basically jams the control channel in the local area such
that the phones can't hear a 'ring' command.

The best thing I can think of to combat the problem is peer pressure.
Getting kicked out of a theatre/restaurant by management for using
a cell phone goes a long way to fixing the problem. Just as we have
no-smoking and dress codes in establishments, so too we can have no
'cell
phone/pager' facilities.

The way our local theatre company handles the problem is to
have a secure area where the patron leaves his phone/pager (if he must
have it on). An usher comes and fetches the owner if a sufficiently
urgent call comes in. (lots of Doctors/LAN administrators up here).

Some hospital ICUs now have RF detectors that go off as a cell phone
user passes through a gateway. I suspect that it's just listening
for the LO or SMPS hash since a human shouldn't be radiating
monochromatic RF.

> >From http://www.fcc.gov/cib/Public_Notices/da992150.html ...
>
> DA 99-2150 Released: October 12, 1999
.....
> The equipment can also be seized and forfeited to the U.S. Government.
>
> OET and CIB wish to emphasize that the above regulations apply to all
> transmitters that are designed to cause interference to, or prevent the
> operation of, other radio communication systems.

So does a Radar gun count as a 'communication system'?
The strict reading of the rules would suggest that one could legally
manufacture radar jammers since they won't interfere with
'communication'.

Robert

2000\03\16@202625 by andy howard

flavicon
face
> As for the copper mesh, this would be barely sufficient. We have glass
that
> has mesh between the laminated layers at work (someones idea of
overkill)
> and the whole building is fully encased in mesh/steel, and cellphones
still
> work, as do pagers, radios and tv. Needless to say, we still ended up
having
> to buy metal closets to test rf gear in, so it ended up being a good
waste
> of alot of money.

> Theoretically, the mesh is good, but in actual use, its decent at
best.

Yes, You're quite right. Just sticking up mesh will give only moderate
amounts
of attenuation, and at some frequencies the mesh may even form a
resonant circuit!  But a properly designed and installed Faraday cage
will eliminate pretty much all of RF in a room. Certainly enough to stop
a cellphone from finding its basestation.

Taken to extremes, this is also the kind of setup used for measuring
extremely small
amounts of RF in research and for testing for EMC compliance etc.  Not
cheap if you want a totally RF-free room, but I suspect it'd be no
problem to reduce the RF enough to stop cellphones from working.










.

2000\03\17@012326 by Harold M Hallikainen

picon face
On Thu, 16 Mar 2000 18:21:05 -0700 Robert Rolf <RemoveMERobert.RolfTakeThisOuTspamUALBERTA.CA>
writes:
>
>
> So does a Radar gun count as a 'communication system'?
> The strict reading of the rules would suggest that one could legally
> manufacture radar jammers since they won't interfere with
> 'communication'.

The FCC doesn't like radar jammers either.  See

http://www.fcc.gov/Bureaus/Compliance/Orders/1997/fcc97404.txt


Harold

________________________________________________________________
YOU'RE PAYING TOO MUCH FOR THE INTERNET!
Juno now offers FREE Internet Access!
Try it today - there's no risk!  For your FREE software, visit:
dl.http://www.juno.com/get/tagj.

2000\03\17@014024 by Sean Breheny

face picon face
It seems to me that the FCC is using some mighty "fuzzy" (in the pejorative
sense!) logic in their arguments in this document!

For one thing, they never seem to address why Rocky Mountain's assertion
that the device doesn't radiate RF between 9kHz and 3GHz is wrong, they
just say that it is wrong.

Also, They seem to turn the consultant's words upsidedown. Rocky Mountain
says that their device doesn't generate or radiate any energy. The
consultant seems to agree,by saying that the only RF component is a mixer
diode, so it can't radiate any energy on its own, it needs an external
source. The FCC then says that the consultant's statement actually agrees
with them and contradicts Rocky Mountain, with no logical statement saying
why!!!!

Sean

At 10:19 PM 3/16/00 -0800, you wrote:
{Quote hidden}

| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
Save lives, please look at http://www.all.org
Personal page: http://www.people.cornell.edu/pages/shb7
spamBeGoneshb7spamBeGonespamcornell.edu ICQ #: 3329174

2000\03\17@015742 by oyvind

flavicon
face
> I just heard from a guy that some restaurants in Japan have installed
> devices that block cell phone calls to prevent users from disturbing
> other patrons.
>
> Any idea how that would work?

Yes.
There is a guy here in Norway that has made such a system.

In short, it works by *detecting* the phones that are within a
certain area and sends a blocking command to the network provider,
which in turn denies this certain cellphone access to the net.

This means it has to be in cooperation with the network provider.

> Thoughts on usefulness in USA? Legality of preventing cell phone use
> in surrounding cars while I'm driving on the freeway? <GRIN> using the
> restroom? <VBG>

:-)

I can see how such a system can be useful in some applications,
cinemas is one example. Don't you hate it if someone's cellphone is
ringing in the middle of a movie?


-¯yvind


_______________________________________________
¯yvind Kaurstad, TakeThisOuToyvindEraseMEspamspam_OUTsafetel.no

Safetel ASA
P.B. 405, N-4067 Stavanger, Norway
Tel: +47 51 81 78 80 (Switchboard)
    +47 51 81 78 82 (Office)
    +47 51 81 78 93 (Fax)

2000\03\17@032050 by Graeme Zimmer

flavicon
face
> That's correct. Any good conducting shielding
> connected to ground (earth)
> will strongly reduce radio waves from both sides.

It does if  .........

(1) it has at least TWO independant layers of VERY fine and high quality
mesh
(2) is Soldered or bonded at ALL the seams and has absolutely no holes (eg
no windows and doors)
(3) and all cables passing through (eg mains, phones) have low pass filters

And BTW, earthing makes little difference at VHF/UHF.
 (how many wavelenghts is the earth lead?)

I once set up a screened room which was about 1/2 km away from a phone
tower.

We never could totally eliminate the break-through..

................... Zim

2000\03\17@032102 by Graeme Zimmer

flavicon
face
> I just heard from a guy that some restaurants in Japan have installed
> devices that block cell phone calls to prevent users from disturbing other
> patrons.

Differs from country to country of course, and it very much it depends what
type of phone system we are talking about (GSM/Analog/CDMA/etc)

But there are two approaches.

(1) Build a jammer (highly illegal and against the phone companies interest,
so you are sure to be busted)

(2) Your phone searches for the strongest base station, so the legit gadget
acts as a real base station, but won't place or  forward any calls.

It _must_ however properly handle 000 emergency calls...

A simpler way is to prominently advertise that the resurant doubles the bill
if your phone rings....

.................. Zim

2000\03\17@034445 by Robert Rolf

picon face
Sean Breheny wrote:
>
> It seems to me that the FCC is using some mighty "fuzzy" (in the pejorative
> sense!) logic in their arguments in this document!

I'll say. I had a pretty good laugh with the contradictions.
Unfortunately when you're the government you can be completely
wrong, but YOU have the power, and infinite money with which to
cover your ass.

>
> For one thing, they never seem to address why Rocky Mountain's assertion
> that the device doesn't radiate RF between 9kHz and 3GHz is wrong, they
> just say that it is wrong.

Exactly. The regs they cite don't cover the frequency where
the jammer operates.

> Also, They seem to turn the consultant's words upsidedown. Rocky Mountain
> says that their device doesn't generate or radiate any energy. The
> consultant seems to agree,by saying that the only RF component is a mixer
> diode, so it can't radiate any energy on its own, it needs an external
> source. The FCC then says that the consultant's statement actually agrees
> with them and contradicts Rocky Mountain, with no logical statement saying
> why!!!!

We're the FCC. We don't have to make sense. We never HAVE!
We make big bucks selling spectrum to private companies.
Resistance is futile. Your spectrum (hams) will be assimilated.

{Quote hidden}

2000\03\17@034900 by Dale Botkin

flavicon
face
On Thu, 16 Mar 2000, Robert Rolf wrote:

> So does a Radar gun count as a 'communication system'?
> The strict reading of the rules would suggest that one could legally
> manufacture radar jammers since they won't interfere with
> 'communication'.

Except that you're not licensed to transmit on 10GHz or whatever other
band the target radar system is using.  Being a ham, I could transmit all
I want on 10.525 or so GHz, which is close to X-band radar...  don't know
if that would mess with the police radar or not.  Maybe a 100mW mobile 10G
beacon?  ;)

I just drive slower now.  In a screaming red Mustang, I don't HAVE to be
speeding to get pulled over :(

Dale
---
The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
               -- Isaac Asimov

2000\03\17@060729 by Alan Pearce

face picon face
>I just heard from a guy that some restaurants in Japan have installed
>devices that block cell phone calls to prevent users from disturbing other
>patrons.

These devices flood the area to be protected with "white noise" at the 900MHz or
1800MHz frequency the phones work at. This provides a signal that is stronger
than the cell phone telemetry channel, and so the phone cannot receive the base
station interrogation requests. the base station then does not get a reply from
the phone, and hence does not know the phone is in its cell to make a
connection.

The simplest way to do something like this is to have a spark gap of some sort
with a piece of wire at the correct length for an aerial. It then becomes the
"original spark gap transmitter" at the frequencies of interest, and if anyone
comes looking for an illegal transmitter it is very hard for them to justify it
as such (it is just my negative ion generator to clear the air sir).

2000\03\17@073856 by Scott WALSH

flavicon
face
The FCC, GSM and RA, depending on which contry you are in, would have rules that
mean that a device you build would need a licence and approval for that device
if it transmits more than a certain amount of RF power.

You can make a device that transmits a little power, but because that
transmitter is physically close to the mobile phone you wish to block, it will
do so.

So it *could* be legal to use such a device.

regards,
SW.

____________________Reply Separator____________________
Subject:    Re: [OT] Cell phone blocking
Author: pic microcontroller discussion list <PICLISTEraseMEspam.....MITVMA.MIT.EDU>
Date:       16/03/00 17:46

> I just heard from a guy that some restaurants in Japan have installed
> devices that block cell phone calls to prevent users from disturbing other
> patrons.
>
> Any idea how that would work?

I don't think it would be technically difficult.  All you would have
to do is have a jammer transmitter on the initial paging channel for
each carrier.  (two transmitters would suffice in most areas)  Then
the phone couldn't hear any paging (i.e. ringing) from the cell site.

I doubt you could liscence this commercially. This is a liscensed
band, and all the equipment is registered with FCC, and they might
take a dim view- do you really WANT to prevent people from dialing
911?  If the FCC wanted to let you do it, it would not be technically
hard...

------------
Barry King, KA1NLH
NRG Systems "Measuring the Wind's Energy"
http://www.nrgsystems.com
Check out the accumulated (PIC) wisdom of the ages at:
PIC/PICList FAQ: http://www.piclist.org

2000\03\17@081847 by Alan Pearce

face picon face
>It does if  .........

>(1) it has at least TWO independant layers of VERY fine and high quality mesh
>(2) is Soldered or bonded at ALL the seams and has absolutely no holes (eg
>no windows and doors)
>(3) and all cables passing through (eg mains, phones) have low pass filters

>And BTW, earthing makes little difference at VHF/UHF.
>  (how many wavelenghts is the earth lead?)

The other thing that needs to be done is to bond the inner cage to the outer
cage at ONE POINT ONLY. This is normally done at the point where the cables pass
through. This means the door has to have 2 separate connections, one for the
outer cage and one for the inner cage.

The room I used one had mesh which was about 1/8 inch square holes. We were
trying to develop a heart monitor in the same room as someone else was working
on a VHF 25 watt transmitter without a case on it!

2000\03\17@082112 by Alan Pearce

face picon face
>between 9kHz and 3GHz is wrong, they
> just say that it is wrong.

I think you are wrong 3Ghz is 3 000 MHz. they were saying their jurisdiction
went up to 3 000 000 MHz, i.e. 3000 GHz.

2000\03\17@084626 by paulb

flavicon
face
Alan Pearce wrote:

> The other thing that needs to be done is to bond the inner cage to the
> outer cage at ONE POINT ONLY.  This is normally done at the point
> where the cables pass through. This means the door has to have 2
> separate connections, one for the outer cage and one for the inner
> cage.

 Dunno about the business of inner and outer cages so much, but the
critical matter of shielding, particularly as it applies to windows, is
that the shielding must be continuous between window or door, and wall,
that is there must be a continuous contact strip all the way around the
window or door, making contact to both the wall mesh and the door/
window mesh at every point.

 This is the most likely point of failure of such shielding systems.
If contact around a window or door is made at only a few points, no
matter how well it is covered with shielding, it will equate to a
complete hole of that size in the wall.

 You should also consider that unless the mesh is covered with an
absorptive layer (a wavelength thickness of graphite-impregnated IC
transport foam would be a likely material), such a conductive cavity
actually *improves* the signal to the phone by funnelling it without
loss out of/ into the opening or openings provided, i.e., the phone is
as effective anywhere inside, as if it were being used at the doorway/
window itself.

 This view of the situation may help to understand the difficulties of
the shielding approach.
--
 Cheers,
       Paul B.

2000\03\17@085918 by Sean Breheny

face picon face
Yeah, now that I think about it again, I think you are right about what
they said. My mind was reading Hz for MHz. Hmmmm, it would seem to me that
my body is probably regulated by the FCC,then. Isn't 3THz in the
medium-temp IR range?

Sean

At 01:18 PM 3/17/00 -0000, you wrote:
>>between 9kHz and 3GHz is wrong, they
>> just say that it is wrong.
>
>I think you are wrong 3Ghz is 3 000 MHz. they were saying their jurisdiction
>went up to 3 000 000 MHz, i.e. 3000 GHz.
>
|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
Save lives, please look at http://www.all.org
Personal page: http://www.people.cornell.edu/pages/shb7
EraseMEshb7spamcornell.edu ICQ #: 3329174

2000\03\17@090722 by Alan Pearce

face picon face
>  Dunno about the business of inner and outer cages so much, but the
>critical matter of shielding, particularly as it applies to windows, is
>that the shielding must be continuous between window or door, and wall,

The unit I worked in was a double walled unit, a layer of mesh on the inside of
the wall (the inner faraday cage) and a layer of mesh on the outside of the wall
(the outer faraday cage). The door had mesh on both sides, and all round the
edge of all four edges there was a double row of phosphor bronze fingers to make
contact with matching copper strips on the door frame, so when the door was
closed, there was no discontinuity in the "electrical wall" that the mesh
provided. The inner faraday cage was connected to the outer faraday cage at one
point only, so any circulating currents induced in the outer cage by whatever
means did not cause a current in the inner cage by being connected at two
points. This made a very effective block against very strong local transmitter
signals when we were trying to measure millivolt low frequency signals.

I agree with your comments about the screen needing to be continuous. Trying to
use the 1/2 inch mesh in reinforced glass will not do it, as you cannot
guarantee that the wires have good contact at each crossing point.

To solve this problem, I am aware of a Civil Aviation centre that was built
adjacent to an airport, which had to have similar mesh to that we used in our
screend cage, all around the walls of the room, including over the windows,
where they tested and repaired radio equipment for airline use.

2000\03\17@090732 by Peter L. Berghold

flavicon
face
On Thu, Mar 16, 2000 at 01:11:53PM -0800, James Newton wrote:
> I just heard from a guy that some restaurants in Japan have installed
> devices that block cell phone calls to prevent users from disturbing other
> patrons.
I've heard of this being done right here in the good ol' USA. Applications for
this that I've heard of is in court rooms (judges hate lawyer's cell phones
going off during court proceedings), *CHURCHES*, as well as resturaunts.

They way it was explained to me is that it is accomplished by sending a
signal in the cell phone frequency range strong enough to surpress the
AGC circuit in the cell phone so it never "sees" legitimate signals from
a cell. Basic RF jamming.

Supposedly the signal strength does not have to be very strong for this
to work.  It all seems over simplified to me, but I suppose in theory it
would work.


--
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Peter L. Berghold                        RemoveMEPeterEraseMEspamEraseMEBerghold.Net
"Linux renders ships                     http://www.berghold.net
NT renders ships useless...."

2000\03\17@091131 by Peter L. Berghold

flavicon
face
On Thu, Mar 16, 2000 at 05:43:17PM -0500, Randy Glenn wrote:
> An easier way to protect a single room from cell phones is to put copper
> mesh in the walls - it will block radio waves, I beleive, if you ground it.
>
Ahh... a Faraday Cage....


--
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Peter L. Berghold                        RemoveMEPeterspam_OUTspamKILLspamBerghold.Net
"Linux renders ships                     http://www.berghold.net
NT renders ships useless...."

2000\03\17@094225 by Quentin

flavicon
face
Question about the legal aspect of things:

Is it illegal to build it or illegal to use it?

'nuff said.

Quentin

2000\03\17@112726 by Quitt, Walter

flavicon
face
Yes, Earth ground is a poor ground.  That's why
there are sooo many radials and buried (under
concrete) wire meshes around my house.  An Earth
ground is only good for routing static away.
It helps during lightning strikes too.  Earth
is considered a losey (SP?) dialectric.

{Original Message removed}

2000\03\17@113344 by Quitt, Walter

flavicon
face
>-----Original Message-----
>From: Robert Rolf [RemoveMERobert.RolfTakeThisOuTspamspamUALBERTA.CA]
>Sent: Friday, March 17, 2000 12:42 AM
>To: EraseMEPICLISTspamspamspamBeGoneMITVMA.MIT.EDU
>Subject: Re: [OT] Cell phone blocking
>
>
>Sean Breheny wrote:
>
>We're the FCC. We don't have to make sense. We never HAVE!
>We make big bucks selling spectrum to private companies.
>Resistance is futile. Your spectrum (hams) will be assimilated.
>
YEP, I sure do hate to mix my CW signal with all those broadcast
stations on 40m!   I also hate those sipid little detectors
that operate in the middle of the UHF ham hand.  I also hate
those long range radars in the ham bands.  It sucks!  We only
have a few hundred KC here and there in the short waves and
a few 10s of MHZ in the higher bands.  It is sad....

Walt WA6FEC

2000\03\17@114204 by Quitt, Walter

flavicon
face
I think it is not considered "prudent" to
transmit in such a manner as to cause harmful
interference to something that is "close by."

{Original Message removed}

2000\03\17@120903 by Don Hyde

flavicon
face
I wonder if it might be possible to design "anti-cellphone wallpaper" that
was covered with little  cell-phone-frequency antennas printed with
semiconductive ink so that they would absorb RF in that band?  It might be
more effective than dense foliage.

> {Original Message removed}

2000\03\17@121109 by Andrew Kelley

picon face
On Fri, 17 Mar 2000 08:30:46 -0800 "Quitt, Walter" <RemoveMEwquittKILLspamspamMICROJOIN.COM>
writes:
> >{Original Message removed}

2000\03\17@155211 by paulb

flavicon
face
Peter L. Berghold wrote:

> (judges hate lawyer's cell phones going off during court proceedings),

 Surely that one is easily fixable?  I thought that constituted
"contempt of court" if warned against in advance, and was summarily
punishable as such?
--
 Cheers,
       Paul B.

2000\03\17@155619 by Peter L. Berghold

flavicon
face
On Sat, Mar 18, 2000 at 07:50:40AM +1100, Paul B. Webster VK2BZC wrote:
>   Surely that one is easily fixable?  I thought that constituted
> "contempt of court" if warned against in advance, and was summarily
> punishable as such?

I'm not a lawyer and don't play one on TV. ;-)

I got that little sniglet (about judges) from a boss of mine who was a
lawyer until she decided to opt out of the rat race that the lawyer life
style quickly becomes.

She still sounds like an attorney at times.....

--
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Peter L. Berghold                        PeterSTOPspamspamspam_OUTBerghold.Net
"Linux renders ships                     http://www.berghold.net
NT renders ships useless...."

2000\03\17@160031 by William Chops Westfield

face picon face
The "cooperative" proposal seems like it could work out wonderfully.
A tiny receiver of some sort would detect which phones were in the
room, and communicate with the cellular provider to temporarilly block
service to those numbers.

1) the cellular providers could collect revenue (from the restaurants/etc)
  for NOT using their resources.
2) Emergency calls could still get through, since the actual blockage is
  at the cellular provider level.  Perhaps the phones could be made to
  simply show up as "busy" to callers, and use the standard "busy signal
  breakthrough" features in telcos to get emergencies through.
3) You could filter out cellphones that were just "walking by" by requiring
  the phone to be detected for a significant period of time before actually
  disabling incoming calls.
4) patrons could still make outgoing calls, or these could be disabled as
  well.
5) arbitrarilly large areas could be covered by connecting the cellular
  receivers together via standard computer networking methods.

Is this technically practical?  Can relatively low-cost equipment detect
the signals that tell the cellular phone system where each phone is?  How
about the political feasability?  Would cellular providers actually agree
to provide such a service?

BillW

2000\03\17@183456 by Graeme Zimmer

flavicon
face
> Question about the legal aspect of things:
> Is it illegal to build it or illegal to use it?

Illegal to possess it..

Gotcha !

...................... Zim

2000\03\17@224815 by carbonbased

flavicon
face
----- Original Message -----
From: "Harold M Hallikainen" <spamBeGoneharoldhallikainenSTOPspamspamEraseMEJUNO.COM>
To: <KILLspamPICLISTspamBeGonespamMITVMA.MIT.EDU>
Sent: Friday, March 17, 2000 1:19 AM
Subject: Re: [OT] Cell phone blocking


{Quote hidden}

I remember one fellow ham that I knew that didn't call it a radar
jammer....instead he claimed to have a microwave transmitter near the grill
of his pickup and had a controller constantly sending out a 'cq' signal at
high power in the ham microwave band (I never actually went to take a look
at it though because it didn't inspire me in any way)...
I donno if it really worked even though he thought it did, and I don't think
that this would really be interperted as not trying to interfere with the
radar guns because when you get right down to it...whether it worked or not,
that was the intent.
Either way...all bets are off now because such a setup would not pass muster
against a laser gun anyways and would give you a false sense of security.



Joe

2000\03\18@023344 by Peter Crowcroft

flavicon
face
<rant>
>I just heard from a guy that some restaurants in Japan have installed
>devices that block cell phone calls to prevent users from disturbing other
>patrons.

I have held off for 2 days and bitten my lip.  BUT

you all seem to assume that mobile phones are a 'bad' thing. That it is a
'rude' minority which are doing it. Well sorry but let me tell you the
other side of the story. Here in Hong Kong there is now 53% ownership of
mobile phones. There is now majority ownership. My maid has one; some of my
workers have them.

You travel on the MTR - underground - and maybe 1 in 10 people are on the
phone at any time. They are using this previously 'wasted' travelling time
to work, gossip and increasingly for the young (sigh!), chat to prospective
boy/girl friends. (Companies to facilitate this latter service are booming.
One sells you the contact phone numbers in chocolate then if you don't like
him/her you eat them and program your phone to block their number so they
cannot call you back. In Japan last month I saw a video phone doing the
same service - no, not in chocolate!))

I have been in the cinema here and there were once 5 people on phones at
one time. There was no chinese peer pressure to stop them. And any
westerner silly enough to try post 1997, would risk not getting out in one
piece.

You just have to face the possibility that list members are in a 'Stop the
World I Want to Get Off' mode. Getting grey-haired and conservative.  For
reasons I don't understand asia and europe (especially Finland) seem to
lead the world in mobile phone usage and uses. North america is lagging way
behind.

Note I am not only talking about handheld phone with the user shouting into
it. (And hell many of the locals here do that naturally without the phone.)
 You can buy the headset and mouthpiece where the user just speaks in a
soft voice. (Reminds me of the 'mumblers' you see shuffling along New York
streets.) I think there lies the future: the mobile phone will vibrate only
to receive calls then the user will use a personal headset to speak in a
soft voice when replying.  After all the objection now is the 'noise' the
mobile phone user makes when talking loudly on the phone - "look I have a
mobile phone". When the novelty wears off and people come to see how much
more productive a mobile phone will make them then there will be majority
acceptance. If not by you then certainly by your children - tucked up in
bed at night talking for hours without you knowing!
</rant>


2. Many thanks for the PLL references. I am looking at doing some kits
using and introducing them.

regards,

Peter Crowcroft
                   DIY Electronics (HK) Ltd
               PO Box 88458, Sham Shui Po, Hong Kong
Voice: 852-2720 0255   Fax: 852-2725 0610    Email: @spam@peter@spam@spamspam_OUTkitsrus.com
                      Web: http://kitsrus.com
----------------------------------------------------------------------

2000\03\18@032018 by William Chops Westfield

face picon face
>> you all seem to assume that mobile phones are a 'bad' thing.

No, being noisy in a place where people should be quiet is a bad thing.
So far, experience seems to indicate that you can't fix this with
technology enabling them to be quieter (ie mumble mikes and vibrators),
since there are plenty of annoying beeps and warbles from phones that
already have vibrators.  Thus the search for "active" technology to
enforce quiet - to solve those people too careless or inconsiderate
to hold their own sound level down.

BillW

2000\03\18@111236 by Marc

flavicon
face
> 1) the cellular providers could collect revenue (from the restaurants/etc)
>    for NOT using their resources.
>
> 2) Emergency calls could still get through, since the actual blockage is
>    at the cellular provider level.  Perhaps the phones could be made to
>    simply show up as "busy" to callers, and use the standard "busy signal
>    breakthrough" features in telcos to get emergencies through.

And certainly the restaurant will give me a 50% off on the bill for spending
my time in such a place.

2000\03\18@114149 by TIM

flavicon
face
i agree of the privateness...when making one feeel
comfortable.......especially a woman..
buzzing beeping..breaks concentration..
{Original Message removed}

2000\03\18@122755 by Dan Michaels

flavicon
face
Peter:
>>> you all seem to assume that mobile phones are a 'bad' thing.
>
BillW wrote:
>No, being noisy in a place where people should be quiet is a bad thing.
>So far, experience seems to indicate that you can't fix this with
>technology enabling them to be quieter (ie mumble mikes and vibrators),
>since there are plenty of annoying beeps and warbles from phones that
>already have vibrators.  Thus the search for "active" technology to
>enforce quiet - to solve those people too careless or inconsiderate
>to hold their own sound level down.
>

Can't help but chime in here.

BillW, possibly a good whack on the side of the head is the best
solution. [BTW, someone recently wrote a book about the unintended
consequences of hi-technology].

<PROBLEM STATEMENT>
It's a cultural thing. Many Americans by nature tend to be extremely
loud and obnoxious. They must figure it's their 1st amendment rights.
And others get aggravated over this - they feel they have a 4th
amendment right to avoid invasion of their privacy (or sanity) by
the 1st amend-iots.
</PROBLEM STATEMENT>

<NON-OBLIGATORY LECTURE>
If you travel widely in europe, as I have, and where you find people
from many countries, the first thing you realize is everybody in the
world can immediately spot an american. In fact, you don't have to
"spot" them, because you can generally "hear" them coming 2 blocks
away. The europeans look at this and quietly shake their heads.
"Americans", they say.

If you sit in a cafe in europe, you "generally" cannot make out
the conversation taking place between 2 europeans at the next
table. In america, you usually have to shout at the person
sitting across from you. Europeans seem to understand something
that too many americans are never taught.

Obviously, america isn't the only place subject to the scourge
of bleeping phones, but most piclisters live here and have to
deal with noisy morons here at home.
</NON-OBLIGATORY LECTURE>

<SOLUTION>
As Peter points out, in Hong Kong, shouting is possibly a way
of life, and everyone adapts to the noise. But, to paraphrase
the NRA (an organization I don't much agree with), "cellular
phones don't aggravate people, people aggravate people".

In a restaurant, my preferred route is to "accidentally" spill
water in the direction of someone who aggravates me - followed
by profuse apologies, so they don't tear my head off, of course.
Important people in fancy clothes generally leave after this.
No one loves a bumbler. In movie theaters, spilling buttered
popcorn works well, along with yelling "shut the f___ up".
</SOLUTION>

<POSTSCRIPT>
Hi-tech isn't the solution to every problem in life.
</POSTSCRIPT>

- Dan Michaels
Oricom Technologies
http://www.sni.net/~oricom
--------------------------
P.S. I once worked in aerospace, inside of those "shielded rooms"
    people have been talking about here. They ain't cheap.
==========================

2000\03\20@213255 by Jeffrey D Spears

flavicon
face
Guess you'll just have to *accidently* put a harmonic on the
carrier frequency then. No?

On Thu, 16 Mar 2000, Harold M Hallikainen wrote:

{Quote hidden}

Jeffrey D. Spears
University of Michigan
College of Engineering

``Double-E, can't spell gEEk without it!''
                       -Captain Gerald M. Bloomfield II, USMC
                        (my brother)

2000\03\20@225230 by Jeffrey D Spears

flavicon
face
Don't forget the nincumpoops who become entranced in conversation
on their stupid cell-phones while operating vehicles travelling
at high rates of speed!

Although I would probably never implement it, sure would be nice
to defeat cell-phone conversations within a thousand meter radius
as I travel down the highway!

ok..jef


On Sat, 18 Mar 2000, William Chops Westfield wrote:

{Quote hidden}

Jeffrey D. Spears
University of Michigan
College of Engineering

``Double-E, can't spell gEEk without it!''
                       -Captain Gerald M. Bloomfield II, USMC
                        (my brother)

2000\03\21@042947 by Joe McCauley

picon face
----- Original Message -----
From: Jeffrey D Spears <TakeThisOuTjspears.....spamTakeThisOuTENGIN.UMICH.EDU>
To: <TakeThisOuTPICLISTKILLspamspamspamMITVMA.MIT.EDU>
Sent: Tuesday, March 21, 2000 3:50 AM
Subject: Re: [OT] Cell phone blocking


> Don't forget the nincumpoops who become entranced in conversation
> on their stupid cell-phones while operating vehicles travelling
> at high rates of speed!
>
> Although I would probably never implement it, sure would be nice
> to defeat cell-phone conversations within a thousand meter radius
> as I travel down the highway!
>
> ok..jef

What about the people who live/work near the highway?????????

Joe

2000\03\21@050345 by Darren King

flavicon
face
Forget the people who live near the highway they would have land lines.  I
hope.  The only time I heard of people who used their cell phones at home
was because they were broke and the phone company cut of their line so they
had to use one of those pay as you go Cell Phones.

I think it could be done, but damn if you didn't get a tumor after using it
for a month or so.

{Original Message removed}

2000\03\21@143809 by Mark Newland

flavicon
face
How about those of us who have cable modem for our internet connection, use
dialpad.com for our outgoing calls and only need a cell phone for incoming
calls.  No reason to waste my money on a 2nd (land based) phone number.

Darren King wrote:

> Forget the people who live near the highway they would have land lines.  I
> hope.  The only time I heard of people who used their cell phones at home
> was because they were broke and the phone company cut of their line so they
> had to use one of those pay as you go Cell Phones.
>
> I think it could be done, but damn if you didn't get a tumor after using it
> for a month or so.
>
> {Original Message removed}

2000\03\21@163821 by David VanHorn

flavicon
face
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

At 11:36 AM 3/21/00 -0800, Mark Newland wrote:
>How about those of us who have cable modem for our internet connection, use
>dialpad.com for our outgoing calls and only need a cell phone for incoming
>calls.  No reason to waste my money on a 2nd (land based) phone number.


You don't fit his world model, so out you go.
Me too I guess.

-----BEGIN PGP SIGNATURE-----
Version: PGPfreeware 6.5.2 for non-commercial use <http://www.pgp.com>

iQA/AwUBONgVyYFlGDz1l6VWEQKGbQCgnbT0psist6sV1LqgwXaSzqq8sBwAoI20
FTJOzfz0A5U0DALgMxuUOFIB
=zNfY
-----END PGP SIGNATURE-----

More... (looser matching)
- Last day of these posts
- In 2000 , 2001 only
- Today
- New search...