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Téléphone portables brouillés dans le métro de Nagoya

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Michael_Voyageur
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MessagePosté le: 28 Aoû 2004 18:11    Sujet du message: Téléphone portables brouillés dans le métro de Nagoya

 Note du Post : 3   Nombre d'avis : 1
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La mairie de Nagoya décide de rendre les portables inutilisables dans son réseau de métro dans les prochaines semaines.

Les compagnies de trains, bus et métro au Japon demandent généralement aux passagers de ne pas utiliser leurs téléphones portables au cours du trajet pour ne pas gêner les autres voyageurs, mais malgré ces appels lancés par les compagnie, quelques passagers récalcitrants continuent d'utiliser leur portables dans les transports en communs.

D'autre part une raison médicale est aussi évoquée, il s'agit de l'hypothèse selon laquelle les emissions radio des téléphones portables pourraient interférer avec les pace-maker de personnes cardiaques équipées de cette prothèse.


Citation:

Nagoya Makes Signals for Mobile Phones Inoperative on Subways, Platforms

August 26, 2004 (TOKYO) -- Nagoya Municipal Management Subway will make mobile phones based on the Personal Digital Communications (PDC) system and the cdma2000 system inoperative on trains and train platforms in August or September.

While the subway platforms were originally excluded from the area of the mobile phone service, the devices can receive radio waves on the upper floor of the subway station where ticket gates are located, according to the Transportation Bureau, City of Nagoya.

Thus, the bureau made it impossible to use the mobile phones on the platforms and in the trains by changing the location and direction of the antennas. The bureau judged that it would be too late to take these measures after a serious accident occurred.

Railway companies in the Kanto area unified their rules on the use of mobile phones in trains in September 2003 and those in the Kansai area, in February 2004. The rule calls on passengers to switch off their mobile phones near the special seats for the aged and disabled. It also requires them to keep their mobile phones in the manner mode and refrain from talking on the phone in other places.

The railway companies have established these common rules for two reasons. One of them is to remove the feeling of discomfort that the passengers would have when they hear the voice of people talking on their mobile phones around them.

The other purpose is to prevent medical equipment, such as pacemakers used by people with heart problems, from malfunctioning. An experiment jointly conducted by the Ministry of Public Management, Home Affairs, Posts and Telecommunications (MPHPT) and the Ministry of Health, Labor and Welfare recently proved that the simultaneous use of certain types of pacemakers and mobile phone causes malfunctions in medical equipment.

Among the rules made by railway companies, those of subway companies are particularly strict.

Nearly half of them call on passengers to keep their mobile phones off while in the trains.

In some subway stations, an antenna is installed at the platform, and mobile phones sometimes can receive strong radio signals when the train comes out of the tunnel.

However, it seems that most passengers are not abiding by the rules, the railway companies said. All they can do is to hope that the passengers voluntarily follow the rule, they said.

Nagoya's transportation bureau has taken a fundamental measure.

In March, the bureau began installing on platforms the antennas for mobile phones based on the W-CDMA system, such as FOMA. The experiments conducted by MPHPT and other organizations have revealed that bringing the W-CDMA-based handset close to the pacemaker would not cause a malfunction of pacemakers when the distance between them is more than 1.4cm.

The bureau said 2cm is the minimum distance for the safe use of mobile phones in trains. However, it is difficult for passengers to find out immediately whether their mobile phone is based on the W-CDMA system.

The transportation bureau, therefore, bans passengers from sending and receiving e-mails as well as talking on their mobile phones while on trains, the bureau said. It also calls on passengers to keep their mobile phones turned off when the train is crowded.

According to the railway companies' spokesmen and officials in charge of this issue, they have not received any reports of trouble between a mobile phone holder and a pacemaker user. However, there was a report from Sapporo, Hokkaido that a pacemaker user felt sick by just seeing a handset, they said.

(Yohei Ichishima, Staff Editor, Nikkei Communications)


Source : Nikkei Electronic Asia

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erwan
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MessagePosté le: 30 Aoû 2004 09:46    Sujet du message: Re: Téléphone portables brouillés dans le métro de Nagoya

 Note du Post : 4   Nombre d'avis : 1
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Michael_Voyageur a écrit:

D'autre part une raison médicale est aussi évoquée, il s'agit de l'hypothèse selon laquelle les emissions radio des téléphones portables pourraient interférer avec les pace-maker de personnes cardiaques équipées de cette prothèse.


C'est pour ca que pres des places prioritaires on est cense couper son telephone completement, le mettre en vibreur n'est pas suffisant (je ne crois pas que cette regle soit respectee, mais bon).

Ce qui m'etonne c'est que les brouilleurs de telephones emettent aussi, donc au lieu de resoudre ce probleme des "telephones qui interferent avec les pace-maker", a mon avis ca l'aggrave en augmentant les emissions...
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Alessandro
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MessagePosté le: 31 Aoû 2004 00:43    Sujet du message:

 Note du Post : 3.5   Nombre d'avis : 2
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Oui en général les brouilleurs de portable émettent également.

Donc un article intéressant, développé par un Japonais Hideo Oka, 'magnetic wood'. Cela consite à un sandwich de bois qui contient des particules magnétiques comme de la ferrite qui stopperait les ondes radio et le micro-ondes et qui n'émet bien sur aucune onde. Cela pourrait résoudre certains problèmes liés aux stimulateurs cardiaques.

( http://www.mercola.com/2002/jul/20/cell_phone.htm )


Citation:
Magnetic wood could be a major plank in the battle against noisy cell phone users. The high-tech material absorbs microwave radio signals, making it impossible to use a mobile phone in any room lined with it. Or a radio for that matter. So theatres and restaurants, for example, can stop people using cell phones on their premises without resorting to signal jammers.

The Anti-Cellphone Sandwich

These are illegal in some countries, including the US, Britain and Australia. Jammers also cause wider problems because their signals can spill out of the building they are covering, interfering with other people's calls.

The magnetic wood - so called because it is packed with minute magnetic particles - is the brainchild of Hideo Oka and a team of electronics engineers at Iwate University in Morioka, northern Japan. They chose wood as their preferred blocking material because it offers more natural, aesthetic options for interior design. Oka hopes that it will soon be possible to buy the novel wood panelling by the metre at your local hardware store.

While normal wood is transparent to radio waves, Oka's blocks them because it contains fine particles of a magnetic material called nickel-zinc ferrite. When an electromagnetic wave hits the ferrite particles, the magnetic part of the wave is absorbed.

Bluetooth Frequencies

The team looked at four different ways of making wood absorb radio waves before hitting on the best one. The first was simply wood coated with a ferrite powder. The others were made by mixing ferrite powder with cider wood powder and pressing it into boards, or impregnating the wood with particles, or sandwiching wood pulp containing ferrite powder between two thin wooden panels.

Oka tested each wood in turn by putting collars of each material over a short antenna that broadcasts radio waves at the typical GSM mobile phone frequencies of 900 megahertz and 1.8 gigahertz.

The antenna can also broadcast at frequencies up to 2.5 gigahertz, which covers the range commonly used for wireless networks like Bluetooth and the emerging IEEE 802.11 standard, better known as Wi-Fi. A receiver measured the strength of the radio waves transmitted through the material.

Ferrite Sandwich


The anti-cellphone sandwich
(Click to enlarge)

In the end, Oka found that ferrite sandwiched between thin sheets of wood performed best. Further tests showed that a 4-millimetre-thick sandwich absorbed the most microwave radiation, cutting the wave's power by 97 per cent. Increasing the thickness of the outer wooden sheets of the sandwich increased the frequency of radio waves that the shield would absorb.

The wood-based shields could be used to make doors and walls for rooms or even entire buildings where mobile phones simply won't work. While the prospect of being forcefully cut off might horrify some cell phone addicts, Oka says theatre goers and restaurant customers might appreciate the silence.

Panels that absorb radio waves could also help with a problem emerging in Japanese cities, where many homes are being fitted with wireless computing networks. If several networks are set up close together, they can interfere with each other. The new panels could divide up the house into different areas, allowing several networks can operate close by.

Oka believes he can make the wood cheap enough for it to be viable. And he now hopes to cut the cost still further by making the panels from recycled magnetic materials and waste wood.

New Scientist June 27, 2002

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