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Sticks
2005-Feb-21, 10:50 PM
In light of the concern about mobile phones causing brain tumours, If I put a piece of aluminium cooking foil between my head and the phone, whould that be an effective barrier from the microwave radiation given out by the mobile phone transmitter? :-?

I am prepared to look odd if it is effective.

To date I do not own a mobile phone and have resisted owning one because of the radiation issue, especially in light of this warning (http://news.bbc.co.uk/1/hi/health/4163003.stm)

01101001
2005-Feb-21, 11:05 PM
A headset (http://www.plantronics.com/north_america/en_US/products/cat1150057/cat1220039) scores considerably lower on the weirdness scale than a tinfoil beanie (http://zapatopi.net/afdb.html).

Charlie in Dayton
2005-Feb-21, 11:35 PM
But the stylish aluminum foil hat ( Personal Model (http://zapatopi.net/afdb.html), Q&A (http://c2.com/cgi/wiki?TinFoilHat), and don't forget your pets (http://urbanlegends.about.com/b/a/033774.htm) ) makes a much more intense and informative personal fashion statement...

Sticks
2005-Feb-22, 11:59 AM
I was thinking along the lines of just using a sheet of aluminium foil between you and the phone rather than a hat of the stuff.

So would aluminium foil block the radiation from the phone or not ?

Amadeus
2005-Feb-22, 12:47 PM
I saw a program a while back where they rang a mobile and whilst it was ringing wraped it up in foil (dont know if it was tin foil or aluminium)
soon as it was wrapped the signal was lost.

Wally
2005-Feb-22, 01:27 PM
But the stylish aluminum foil hat ( Personal Model (http://zapatopi.net/afdb.html), Q&A (http://c2.com/cgi/wiki?TinFoilHat), and don't forget your pets (http://urbanlegends.about.com/b/a/033774.htm) ) makes a much more intense and informative personal fashion statement...

=D> =D> =D>

I love step 7 in particular! :D

George
2005-Feb-22, 01:38 PM
But the stylish aluminum foil hat ( Personal Model (http://zapatopi.net/afdb.html), Q&A (http://c2.com/cgi/wiki?TinFoilHat), and don't forget your pets (http://urbanlegends.about.com/b/a/033774.htm) ) makes a much more intense and informative personal fashion statement...

:lol:

Swift
2005-Feb-22, 03:26 PM
But the stylish aluminum foil hat ( Personal Model (http://zapatopi.net/afdb.html), Q&A (http://c2.com/cgi/wiki?TinFoilHat), and don't forget your pets (http://urbanlegends.about.com/b/a/033774.htm) ) makes a much more intense and informative personal fashion statement...

:lol:
Like the expression on the cat's face for the pet one. It's cat for "I'm going to kill you" :D

zebo-the-fat
2005-Feb-22, 07:24 PM
I use "hands free" kit, it should help reduce any RF radiation to my head when in use (the phone not the head!). Two things occur to me, I normaly wear my phone on a belt clip, what about radiation exposure to my kidneys and other gloppy bits? (phones radiate pulses even when not in use), has anyone done any studies on RF from bluetooth headsets? (I know they are very low power compared to phones) :o

enginelessjohn
2005-Feb-23, 10:53 AM
Right time for a bit of a lecture. Used to design mobile phones for Ericsson, so I've got a wee bit background in this.

RF energy conducted into a human body is measured by looking at the specific absorption rate, or SAR, and is measured in watts per kilogram. there is a brief description at

http://www.emctech.com.au/sar4/aboutSAR.html

When an antenna is placed near a lump of squishy dielectric (aka the human body) the energy in the near field of the antenna tends to be stored in the higher dielectric, courtesy of Maxwell's equations. The antenna tends to excite the electrons in this dielectric and heat it up. However this doesn't explain the variations between phones. When the phone transmits not all the energy from the radio goes into the antenna. Some of this gets reflected back into the phone ground plane, and then re-radiates into your head. Different phones have different antennas, ergo different SAR values.

The two simplest ways of reducing this are to reduce the amount of power transmitted by the phone (which basestations do automatically if they can), or to move the antenna near field clear of the dielectric, a distance of around about 600 mm for 900MHz.

A patch of tinfoil would do nothing. All that will happen is currents will be coupled into the foil and then re-radiate back into your head, arguably making things worse. Theoretically grounding the tinfoil will help, the problem is getting a low impedance grounding. A bit of wire is no good. The only thing you'll achive with a bit of tinfoil is looking like you fell asleep while preparing a roast dinner.

The BBC news article linked to contains the


The latest study by Sir William Stewart says there is still no proof mobile phones are unsafe, but warns precautionary steps should be taken.

The trouble with the biological effects of RF is that alot of the evidence is confusing and contradictory. There isn't anything definative either way and lots of very minor changes can make a huge difference.

Wrapping a phone in tinfoil will stop the phone from working as the very very low RF signal from the base station won't get through the tinfoil to the phone. If the received signal does get through, it will tell the phone to transmit at full power so it has a chance of receiving that signal. So that won't achive a great deal either. This is essentially the same as what happens with the SAR blocking antenna caps.

Bluetooth equipment transmits at 1/1000 of the power of a phone, so SAR is much less of an issue here. I use a bluetooth headset while in the car (to keep within the law in the UK) although I'm conviced I look like an idiot while wearing one (the Nathan Barley effect?). Wired hands free kits should reduce the power levels, provided you don't wind the cable round the antenna. There is still some chance RF could be conducted out of the cable, and reradiated into your head, but it is somewhat reduced.

While the phone is camped onto a network static in a cell, it typically only transmits for 0.6ms very 2 minutes or so. I've measured this... When switching between cells they transmit a bit more, maybe a few timeslots worth. So when not talking, then phone will not be having very much of an effect. Of course when talking, you will be radiating all that nice squishy dielectric again.....

To summarise after all that.... I use a mobile phone, about an hour a month in total. I find having one incredibly convenient, and that outweighs the possible biological effects, which are also reduced from my very limited use. You have to make the decision as to whether there is a case for you having one.

This is also an area where there is much pseudoscience and lots of agendas going on, so feel free to ask any questions, which I'll be happy to answer as I no longer depend on the mobile phone industry to pay my mortgage. :)

Cheers
John

zebo-the-fat
2005-Feb-23, 11:41 AM
Very informative reply! :D I tried a bluetooth headset but it was no use to me, I have very floppy ears and it kept falling off! :( I use a (wired) hand free set with the cable wrapped a few times around a ferrite ring to reduce any RF passing up the cable.

swansont
2005-Feb-23, 11:51 AM
Anybody ever measure the SAR from the sun?

Amadeus
2005-Feb-23, 12:30 PM
This is also an area where there is much pseudoscience and lots of agendas going on, so feel free to ask any questions, which I'll be happy to answer as I no longer depend on the mobile phone industry to pay my mortgage. :)


What is your take on the effects of Mobile transmitter masts?
Would you feel ok to live near one?

enginelessjohn
2005-Feb-23, 04:13 PM
What is your take on the effects of Mobile transmitter masts?
Would you feel ok to live near one?


Oooooh, loaded topic....

Phone masts transmit at higher power levels but are typically metres away from anywhere you can actually get at. Take a look at page 23 and 24 of this (http://www.nrpb.org/publications/archive/reports/2000/nrpb_r321.pdf) document from the NRPB. It shows the mesured signal from a pair of masts in the two frequency bands used in the UK. And the summary of this report is that levels are typically so low as to not be considered hazardous. Additionally standing at the base of an antenna will result in very low power densities as the antennas used are directional.

People's objections to mobile masts are (in my opinion) primarily aesthetic, backed up by some psychosomatic symptoms. Having seen some of the devices sold to protect people (such as this (http://www.powerwatch.org.uk/sales/screen/headnet.asp)) that can be the only rational scientific conclusion. To see what a rf screened chamber looks like pop that string into google and see what you get.

Would I want to live next to a transmitter? Well I checked

http://www.sitefinder.radio.gov.uk/

And I currently live within 300 metres of 5 of them. How close is close? I'd hesitate to have a mast in my back garden but that would be because it make the house trickier to sell in the future. Not for any health effects.

Cheers
John

Sticks
2005-Feb-23, 10:22 PM
The BBC have a page here (http://www.bbc.co.uk/sn/tvradio/programmes/shouldiworryabout/mobiles.shtml) which has a Real Player movie clip here (http://www.bbc.co.uk/sn/tvradio/programmes/shouldiworryabout/realmedia/siwa_mobiles.ram) where a presenter tries to use the mobile phones to microwave an egg.



So when not talking, then phone will not be having very much of an effect. Of course when talking, you will be radiating all that nice squishy dielectric again.....


Were the BBC pulling a fast one in this being an invalid test, as nobody was talking on them.

Was The ear test also a red herring test as well?


If I had a mobile, when it was not in use I probably would keep it in aluminium foil, because organisations (and any individual who chooses to abuse their position) can track you down as your mobile is like a mini transponder.

Remember the film Enemy of the State which shows the falacy of the old chestnut if you have nothing to hide you have nothing to fear...

01101001
2005-Feb-23, 11:50 PM
If I had a mobile, when it was not in use I probably would keep it in aluminium foil, because organisations (and any individual who chooses to abuse their position) can track you down as your mobile is like a mini transponder.
Since you don't seem to want to use one for incoming calls, you could just turn it off between uses.

Trebuchet
2005-Feb-24, 12:46 AM
....People's objections to mobile masts are (in my opinion) primarily aesthetic....

It's not just that they're so ugly, they're EVERYWHERE! I counted them on my drive home from work the other day, less than 5 miles. Eighteen! Including some on buildings, water towers, and oversized utility poles.

W.F. Tomba
2005-Feb-24, 12:51 AM
....People's objections to mobile masts are (in my opinion) primarily aesthetic....

It's not just that they're so ugly, they're EVERYWHERE! I counted them on my drive home from work the other day, less than 5 miles. Eighteen! Including some on buildings, water towers, and oversized utility poles.
I've occasionally seen them painted green and brown to look like trees. Once I even saw one with fake branches and needles attached to it. Causes a bit of a double-take when you pass it on the highway.

Maksutov
2005-Feb-24, 12:53 AM
....People's objections to mobile masts are (in my opinion) primarily aesthetic....

It's not just that they're so ugly, they're EVERYWHERE! I counted them on my drive home from work the other day, less than 5 miles. Eighteen! Including some on buildings, water towers, and oversized utility poles.
I agree.

I call them "yuckie towers". They're there so the yuckies can drive around in their SUVs, Benzs, and Beemers while making shady business deals without having to go through the horrible inconvenience of using a land line.

Got to get me one of those "Hang Up And Drive!" bumper stickers...

01101001
2005-Feb-24, 01:36 AM
I've occasionally seen them painted green and brown to look like trees. Once I even saw one with fake branches and needles attached to it.
FraudFrond.com (http://www.fraudfrond.com/)


This website pays homage to the fake trees that disguise our cell phone towers. Have you seen these things??! Every time I see a Bogus Botanical or a Counterfeit Conifer, I can't help giggling at the absurdity of it all. These Sham Shrubs have been manufactured so that you and I can communicate with each other, while protecting our delicate aesthetic sensibilities.

Sticks
2005-Feb-24, 05:09 AM
If I had a mobile, when it was not in use I probably would keep it in aluminium foil, because organisations (and any individual who chooses to abuse their position) can track you down as your mobile is like a mini transponder.
Since you don't seem to want to use one for incoming calls, you could just turn it off between uses.

I thought they were still trackerble, even when "switched off " :-?

01101001
2005-Feb-24, 05:16 AM
Since you don't seem to want to use one for incoming calls, you could just turn it off between uses.
I thought they were still trackerble, even when "switched off " :-?
I wouldn't think so, when off-off -- not just "on-hook", able to receive, but powered off. If you are still mistrustful, you could always remove the battery. It can't talk to a tower without power.

Sticks
2005-Feb-24, 09:39 AM
But what about those experiments in the BBC film clips in the earlier links I posted, were they valid or as I suspect seriously flawed?

enginelessjohn
2005-Feb-24, 09:46 AM
The BBC have a page here (http://www.bbc.co.uk/sn/tvradio/programmes/shouldiworryabout/mobiles.shtml) which has a Real Player movie clip here (http://www.bbc.co.uk/sn/tvradio/programmes/shouldiworryabout/realmedia/siwa_mobiles.ram) where a presenter tries to use the mobile phones to microwave an egg.



So when not talking, then phone will not be having very much of an effect. Of course when talking, you will be radiating all that nice squishy dielectric again.....


Were the BBC pulling a fast one in this being an invalid test, as nobody was talking on them.

Was The ear test also a red herring test as well?


If I had a mobile, when it was not in use I probably would keep it in aluminium foil, because organisations (and any individual who chooses to abuse their position) can track you down as your mobile is like a mini transponder.

Remember the film Enemy of the State which shows the falacy of the old chestnut if you have nothing to hide you have nothing to fear...

Okay I should have been clearer. When not making a call i.e. the phone is camped onto a network it won't be having very much of an effect. There is a feature on some phones called discontinuous transmit or DTX, which to save battery life stops the phone transmitting while you are silent, but this reduces call quality, and I don't think any of the UK networks use it.

I saw a couple of the "Should I worry about" programs, not the phone one though. The general impression I got was that they were setting out to debunk popular scientific myths. It's therefore reasonable to assume that the experiments were done for real, and both would be easy to replicate. If your are want to be sure about transmitting, place the phones next to a loudspeaker playing pleasant music of your choice..... :D

Tracking with mobile phones depends on knowing the cell you are in, and triangulating by time delays the messages to other cell antennas. This has been developed as part of the E-911 FCC requirements, so that when someone makes an emergency call, the position of the caller can be determined. It's accurate to about 100 metres, which is of limited use in a town imho. If you are concerned with privacy I'd be more concerned about using credit/debit cards, loyalty cards, flying on airlines etc. All of this information gives much more precise information for a lot less effort than trying to triangulate someone's position using their phone. And if you are that concerned, just switch it off when not in use. There is no remote switch on facility.

If you want to know exactly what a phone can do (and have real trouble sleeping.... :D ) take a look at the specifcations section of

http://www.3gpp.org/

It's all freely available if exceeding dull reading....

Cheers
John

Sticks
2005-Feb-24, 01:35 PM
I heard from, IIRC my parent's next door neighbour that one of Yassar Arafat's men was taken out by the Israelies, by locking a missile onto his mobile phone frequency.

Not that I am expecting a little something from Mossad, but it does make one paranoid 8-[

enginelessjohn
2005-Feb-24, 02:11 PM
I heard from, IIRC my parent's next door neighbour that one of Yassar Arafat's men was taken out by the Israelies, by locking a missile onto his mobile phone frequency.

Not that I am expecting a little something from Mossad, but it does make one paranoid 8-[

Seems unlikely. For one, 8 phones can use the same transmit frequency at any one time in any one cell. So which one is your target? I'm sure there is someone who knows about missiles here who can shed some light on how guidance systems work.

Cheers
John

Kizarvexis
2005-Feb-24, 02:48 PM
I heard from, IIRC my parent's next door neighbour that one of Yassar Arafat's men was taken out by the Israelies, by locking a missile onto his mobile phone frequency.

Not that I am expecting a little something from Mossad, but it does make one paranoid 8-[

I remember an story from a few years ago where the Israelis engineered a situation where a terrorist had his cell phone swapped for one that the Israelis planted that had a small bomb inside. Supposedly the Mossad dialed him up and then exploded the bomb by remote control. I did a quick google search but came up blank because more recent stories about cell phones used as detonators came up instead. Can anyone point me to the story?

Kizarvexis

Sticks
2005-Feb-24, 02:52 PM
As JayUtah is to Apollo so enginelessjohn is to Mobile phones

:)

maybe we should have a list of who is expert on what

meanwhile can we have an answer about the missile guidance system?

on the dummy phone / Bomb could it be that the missile story is confused with that one? :-?

Trebuchet
2005-Feb-24, 08:03 PM
I've occasionally seen them painted green and brown to look like trees. Once I even saw one with fake branches and needles attached to it.
FraudFrond.com (http://www.fraudfrond.com/)


This website pays homage to the fake trees that disguise our cell phone towers. Have you seen these things??! Every time I see a Bogus Botanical or a Counterfeit Conifer, I can't help giggling at the absurdity of it all. These Sham Shrubs have been manufactured so that you and I can communicate with each other, while protecting our delicate aesthetic sensibilities.

That's pretty funny! I must confess I've never seen one disguised as a tree -- perhaps I've been getting fooled. There's a spectacularly ugly one north of Seattle disguised as a church tower. Three wooden pole legs with a sort of hut on top, complete with mock-gothic windows. The hut keeps growing as they add more antennae.

BTW, I recounted last night and found 20 on the way home.

Sticks
2005-Feb-26, 10:13 PM
Missile locks on mobile phones anyone?

On another concern of mine, and this includes cordless land line telephones, is the evesdropper listening in. I know this can be done with those cordless phones, because we used to do it with an old model. Any radio plugged into the mains, on longwave could pick up the signals to and from the handset on a cordless telephone. (This was well before cell phones)

Now, if I am telephoning anyone where I have to give out banking information I use a standard telephone, with a wire from the handset to the base unit so my details are not broadcast to anyone with a radio.

Now the situation for mobiles has to be worse, as I once recall hearing of a scam where criminals went out with some kind of scanning equipment that would pick up any mobile phone and collect enough information to make a clone of your phone so they could run up bills on your account.

:o

W.F. Tomba
2005-Feb-26, 10:21 PM
Now the situation for mobiles has to be worse, as I once recall hearing of a scam where criminals went out with some kind of scanning equipment that would pick up any mobile phone and collect enough information to make a clone of your phone so they could run up bills on your account.
Happened to my dad once. All of a sudden strange charges started showing up on his account for calls that he hadn't made. Turns out there was a large cellphone account-stealing operation in a certain area he had driven through.

ktesibios
2005-Feb-27, 03:28 AM
People's objections to mobile masts are (in my opinion) primarily aesthetic, backed up by some psychosomatic symptoms. Having seen some of the devices sold to protect people (such as this (http://www.powerwatch.org.uk/sales/screen/headnet.asp)) that can be the only rational scientific conclusion. To see what a rf screened chamber looks like pop that string into google and see what you get.


It works a little better if you try Googling "rf shielded chamber" ("shielded" is USAian for "screened")



I call them "yuckie towers". They're there so the yuckies can drive around in their SUVs, Benzs, and Beemers while making shady business deals without having to go through the horrible inconvenience of using a land line.


Or the inconvenience of paying attention to minor details like not smashing into my car...



Like the expression on the cat's face for the pet one. It's cat for "I'm going to kill you"


Actually, that expression translates as "I'll have my revenge. When you least expect it. This I vow." :wink:

enginelessjohn
2005-Feb-28, 09:12 AM
As JayUtah is to Apollo so enginelessjohn is to Mobile phones

:)



Well, hardly, but thanks for the compliment.... :D

Anyway,



Now, if I am telephoning anyone where I have to give out banking information I use a standard telephone, with a wire from the handset to the base unit so my details are not broadcast to anyone with a radio.

Now the situation for mobiles has to be worse, as I once recall hearing of a scam where criminals went out with some kind of scanning equipment that would pick up any mobile phone and collect enough information to make a clone of your phone so they could run up bills on your account.



Any telephone system that uses some form of digital modulation is very difficult to intercept using a radio. For example if you have a modern cordless phone (DECT for example), or a GSM phone.

When I was in my final year at university, in 1993, the RF lab had a scanner, and if you scanned around the old analogue mobile phone band, you could quite often hear half of a mobile phone conversation. Although most of the time 10,000 worth of scanner was tuned into Radio 1..... In fact around that time there was a dance act called "Scanner" that sampled these conversations, and played them over a beat.

However since about 1997 pretty much every phone sold in the UK has been a GSM phone. These use digital modulation, and then break the ones and zeros up into packets 0.577ms long and transmit them every 4.6ms. This is called time division multiple access or TDMA. To further complicate things for the would be eavesdropper, phone networks encrypt the transmission as standard. If it ever gets switched off, a warning appears on the phone, from memory an exclamation mark, along with a text warning. I've never seen this on a network though, only on basestation simulators in the lab. Again all of this is listed in the 3GPP specs I posted a link to a while back.

The upshot of this is that the only simple way for someone to get your bank details while listening to your phone calls, is for them to be standing next to you while you make the call. Tapping a mobile phone would require access to the network, and patching into the computer that is handling the call routing. And while I'm certain this is possible, the practicalities of it being done by any unauthorised party is very very very unlikely (i.e. being hit by lightning while holding a winning lottery ticket :) ) In other words, arguably more secure than a land line.

The US, I believe still uses an analogue standard called AMPS, but there are now GSM networks there, along with CDMA (code divison multiple access) which I imagine are as secure, though I've no experience of them.

Cheers
John

Sticks
2005-Mar-26, 07:13 AM
I have sold out :(

I have got one of those mobile telephonic devices on a Virgin pay as you go basis

I use it more for sending text messages, a sort of e-mail that you pay for. (BTW when are they bringing in that bill to charge for each e-mail :P )

However I noticed a something quite disturbing with it, so could eningeless john help me out here

When I switch it on next to my PC, after a minute or so of my phone "booting up" I heard a stange electronic signlal on my PC, not normally there a dit dit dit dit dit dit etc. kind of noise

what is happeneing here?

I have repeated this experiment successfully and I have observed this when I was listening to a walkman.

What is this signal
The fact that I have heard this, does this mean my phone is not EMC compliant.
Is this signal likeley to cause any harm to biological materials or to electronic systems

Converseley, is my PC likely to cause it a problem in terms of opperations?

8-[

Sticks
2005-Mar-26, 05:13 PM
After listening to it again it seems to be a dit - didi-dit didi-dit didi-dit

I could vaguely understand it interfering with my walkman, but my PC sound system is not hooked up to any arial :-?

smallfluffykat
2005-Mar-27, 01:07 PM
I could vaguely understand it interfering with my walkman, but my PC sound system is not hooked up to any arial :-?

Does your PC sound system come with external speakers? Unshielded speakers will often pick up this noise (characteristic of mobiles) as the mobile communicates with the groundstation.

This is how I understand it - when enginelessjohn signs on again no doubt he can give you a better answer or correct me if I'm wrong.

This signal will no cause any harm to your PC. It's just your speakers/speaker cables acting like an antenna.

For the most amusing examples of this happening go to a conference where the audio equipment is unshielded and then watch the audience funble around embarrassed as they 'remember' to turn their phones off when this noise gets played immensely loudly over the loudspeaker system ;-)

Sticks
2005-Mar-27, 01:58 PM
Yes they are external speakers

Sticks
2005-Mar-27, 02:10 PM
Most recent picture of the set up I have

http://www.stickings90.freeserve.co.uk/images/currentsetup.jpg

Speakers on either side of the monitor

Morrolan
2005-Mar-28, 06:20 AM
After listening to it again it seems to be a dit - didi-dit didi-dit didi-dit

I could vaguely understand it interfering with my walkman, but my PC sound system is not hooked up to any arial :-?

that's what i always call the 'Prancing Horses'... :)

IIRC, it's your cell phone emitting a signal to make sure it's still connected to a network/tower or something.

all speakers will pick this up as they are receivers of signal.

Sticks
2005-Mar-28, 12:00 PM
The noise (http://www.gsne03768.pwp.blueyonder.co.uk/audio/phonenoise.wav) as the phone is switched on

sometimes when the phone is just sitting by the PC it is of a louder and longer duration :-k

Sticks
2005-Mar-30, 04:12 PM
The noise (http://www.gsne03768.pwp.blueyonder.co.uk/audio/phonenoise02.wav) as the phone is switched on

sometimes when the phone is just sitting by the PC it is of a louder and longer duration :-k

I discovered that I get this sound when someone sends me a text message. I found out also that one of my webmail accounts can send messages to mobiles. So for an experiment, I prepared an e-mail to my phone, which was placed under one of my speakers. I dangled my microphone infront of the speaker and then set sound recorder going and then pressed send on the e-mail.

A second or so later I got this (http://www.gsne03768.pwp.blueyonder.co.uk/audio/phonenoise02.wav)

One of these days, I am going to get a life :)

enginelessjohn
2005-Mar-31, 09:23 AM
Hi all,

Sorry for the delay, didn't notice the thread till now. (don't have the notification switched on, get enough email as it is.....)

smallfluffykat is exactly correct, the speaker cables do work as an antenna, and the dit-dit-dit sound is caused by the phone transmitting. The pitch of the dits is goverened by the repetition frequency of the TDMA pulses and the dits themselves are the phone transmitting and waiting for a response. It will do this when talking, receiving a text message, or camping onto or handing over between cells.

I should also stress that it will do no damage to you computer or walkman. Part of the EMC standards is radiated immunity testing, which tests exactly this. Radiated emmissions of phones are also tested to EMC standards defined either by 3GPP or FCC, both of which are similar, and while they are allowed to transmit at certain powers at certain frequencies, the signal levels have to be 10^9 times smaller at other frequencies. I've done this testing, and got a couple of phones through it (Fun...... :roll:) Every phone design sold has to conform to this.

Interestingly this is the reason why you shouldn't use a phone inside an aeroplane, as the dit-dit sounds can confuse navigation aids and other systems, triggering false alarms etc. You can also get older PC monitors to flicker by placing a phone next to them, and I have heard stories of people in call centres using this as way of discretely answering thier mobiles. However the simple way to stop these effects as to move the phone away from whatever is picking up the RF. More than a couple of inches should do the job.

Cheers
John

Sticks
2005-Apr-10, 08:45 PM
Has this anything to do with why they must be switched off in a petrol station or the whole facility will erupt in a fire ball :-? (So the safety guys say)

Aside 2: I believe there was an episode of CSI Miami where they had a guy who had been siphoning off gassoline from boats, and when he answered his mobile it ignited the gasoline vapours still in his mouth and innards - how likely was that?

Jorge
2005-Apr-10, 09:39 PM
i have a mobile phone related question too...
i have a protective erm whats ik called bag/skin/coat thing to keep dust out of my mobile phone, it has a magnet at the back ti attacht it to a belt.
a very stong one i might add!

i used the same bag on my T200 and now on my T310,

my T200 works fine for a long time but once i got the protective thingy the batter charge seemed to declyne very fast! i had it replace 2x before my warenty ran out. the T310 didn't suffer from it for 1y but now is tarting to have the same effect.

Could it be becouse of the magnet or is it normal batter decale?

Metricyard
2005-Apr-10, 10:04 PM
I heard from, IIRC my parent's next door neighbour that one of Yassar Arafat's men was taken out by the Israelies, by locking a missile onto his mobile phone frequency.

Not that I am expecting a little something from Mossad, but it does make one paranoid 8-[

Not really, but if one day you see armed black helicopters circling your house, yank the battery out of the phone right away. :lol:

zebo-the-fat
2005-Apr-11, 07:17 AM
my T200 works fine for a long time but once i got the protective thingy the batter charge seemed to declyne very fast! i had it replace 2x before my warenty ran out. the T310 didn't suffer from it for 1y but now is tarting to have the same effect.

The "protective" cover will reduce the amount of RF radiation the phone transmits and receives, so the phone thinks that it is in a low signal strength area. To compensate, it increases the output level, so the end result is that the phone runs at high power all the time draining the batteries faster and giving out MORE RF radiation!

enginelessjohn
2005-Apr-11, 09:33 AM
Ah the Sony Ericsson T200. One of mine....... Known to the engineers as "the hamster coffin" esp, when in black.... :D Purely an aesthic thing, no hamsters were harmed in the making of this phone... :D

A magnet affect the battery. A phone holster shouldn't significantly alter the RF performance, but it depends where the magnet is. If it is at the top of the phone, then it will detune the antenna, causing reduced battery life. An easy test is to take the phone out of the holster and see if the battery lasts longer.

It is possible that the way the phone is charged is affecting the battery. Lithium Ion batteries have a finite life, dependant on the number of charges. From memory its about 300 to 400 cycles. Having used phones with that chipset for the last 4 years, I'd expect the battery to run for around 5 days for a light user (2 to 3 minutes of calls a day, but not switched off) to a couple of days for a heavier user (lots of calls.....), so if you've always charged your phone every day the battery would start to decay after a year or so.

There are a number of urban legends about mobile phones and petrol stations and snopes has this to say...

http://www.snopes.com/autos/hazards/gasvapor.asp

There are also claims that the RF energy from the phone will affect the fuel counter in the pump, although this sounds like a myth to me as well.

My understanding is this. Following from the Piper Alpha fire in the late 80s, the oil companies got really really touchy about ESD. This apparently included instructions to staff to always hold handrails when going downstairs, so any static electricity would be dissipated. About the same time mobile phones were starting to become common, and as they weren't designed to oil platform safety standards and the simplest way to address the problem in the minds of the Safety people was to ban their use. (Don't get me started on QA/safety logic.....)

In reality the EM fields generated by a phone don't have enough potential to ignite fuel, however if a phone battery is punctured the chemical reaction of the battery will cause spark and could potentially explode. I have seen this being done, and I do not recommend that anyone tries it. You have been warned. Therefore if you drop your phone, and the battery somehow gets spiked there is a chance a fire could start.

Re the CSI Miami story, I'd point you in the direction of the Simpsons, where any vehicle (including skateboards) that crashes explodes into flame..... :D

Cheers
John

enginelessjohn
2005-Apr-12, 10:53 AM
Mobile phones 'safe for brains' Says the BBC....

http://news.bbc.co.uk/1/hi/health/4432755.stm

In other words, we still need to do more research to get some definative data.

Cheers
John

Jorge
2005-Apr-12, 09:07 PM
Ah the Sony Ericsson T200. One of mine....... Known to the engineers as "the hamster coffin" esp, when in black.... :D Purely an aesthic thing, no hamsters were harmed in the making of this phone... :D

A magnet affect the battery. A phone holster shouldn't significantly alter the RF performance, but it depends where the magnet is. If it is at the top of the phone, then it will detune the antenna, causing reduced battery life. An easy test is to take the phone out of the holster and see if the battery lasts longer.

It is possible that the way the phone is charged is affecting the battery. Lithium Ion batteries have a finite life, dependant on the number of charges. From memory its about 300 to 400 cycles. Having used phones with that chipset for the last 4 years, I'd expect the battery to run for around 5 days for a light user (2 to 3 minutes of calls a day, but not switched off) to a couple of days for a heavier user (lots of calls.....), so if you've always charged your phone every day the battery would start to decay after a year or so.


I plug in my phone for a charge every 3 days becouse it the baterie indicated turn yellow(well on the T310) on the T200 i used to plug it in if the batterly was 1/4 left.

the magnet is located at well the exact center of the back, over the battery
if i remove ther phone form it protective case the battery doesn't seem to last longer, but the nor the reception is any better(might be becouse there is a base station about 100m from my room) i only manged to get 5 new scratches on the screen today, the rest it was the same.

well if the battery dies soon, i'll have a excuse to get a new one lol
btw how come dropping and ericssone on the head always turns it off? while dropping it on the other side doesn't?

enginelessjohn
2005-Apr-13, 08:09 AM
Sounds like you're doing the right things charging, and the magnet is in a position where it shouldn't affect things. It may be the battery quality has slipped to give a cost improvement.

In terms of checking signal levels you need to be somewhere where signal is low, to be able to see any difference from the bars on the screen. Even then it isn't a calibrated measurement. That said if the magnet is away from the antenna you shouldn't see a huge difference with or without the case.

Switching off when dropping is probably due to the spring pins on the battery connector springing open for a second. It shouldn't do this, but then I used to have a calculator that could be switched on and off by hitting it against a desk. Got to love Texas Instruments.....

Cheers
John

Jorge
2005-Apr-13, 06:32 PM
ok, thanx for the explenation :D