New interesting chart for everyone to enjoy, this month's topic is the relationship between mobile phone and aircraft. We all know that the phone you want to turn off all electronic devices, even tune into "flight mode" for mobile phone. But when asked why, in General, only the "this will interfere with the aircraft of electronic equipment" on such grounds. We, from the technical point of view as you carefully explaining exactly why can't I open the mobile phone on the plane, or even make the call.
Mobile phone and aircraft
Mobile phones are not radio transmitter that is (China Civil Aviation and) United States Federal Aviation Administration prohibits the use in civil aircraft — unless a frame commercial aircraft or private aircraft for pilots that it does not interfere with aircraft of electronic equipment. Regardless of the pilot believed that the device has more security, flight cell phone calls are United States Federal Communications Commission prohibited.
The Federal Communications Commission (FCC) worry about flight cell phone use can disrupt the mobile system base station operation. Federal Aviation Administration (FAA) worry about flight cell phone use can disrupt navigation, communications and other important air electronic systems work. There are media reports claimed that laptops, cell phones and electronic devices is prohibited, on the United States Department of Homeland Security's Transportation Security Administration said, will continue to allow the device to take the plane.
According to channel multiplexing, and the phone's actions, the phone may violate allows channel reuse most of the work.
Base station is the honeycomb cells (cell). Two adjacent cell edge cell phone signal is very weak. With its distance, the signal is weak (until you get to the "dead zone"). This requires the allow an arbitrary one channel is occupied by a cell phone in a non-adjacent cells of other phone reuse. Therefore, in the same geographical location while channel limited, but you can meet thousands of people at the same time on the phone.
If you fly over the city plane on a mobile telephone operations, many different units of the base station and mobile is equidistant at this time. Base stations are think cell phones in their coverage. Mobile phones can occupy a base station free channels, but will be the same channel group to another base station, and the base station on the channel may have been occupied. This can lead to interference with the ongoing call. It is also possible to control the base station of the program will crash. Even if the program control system can cope with multiple non-adjacent cells from the same phone request processing, the best results also contribute to the overall system efficiency is extremely low.
Another worry is the mobile output power. Because the base station distance relative to the aircraft, the mobile phone must be fully open, use the HP maximum power to find a signal. This will increase the interference on the risk of electronic equipment.
In theory, aircraft interior wiring installation shield can stop interfering signal into the cable. However, the aging line protection may be damaged (or were not installed protective measures), the device can transmit signals during the interference.
In fact, more people agree to the ban on cell phone is not out of technical reasons, but rather the fear of loud talking on the telephone noise nuisance sleep.
People play a cell phone's voice often than people talking voice sound. Do you know why?
1. people will unconsciously through the listening your own voice to adjust the volume of their conversation. Mobile phone cannot provide sufficient side tone (I talk voice volume after copying codes) as feedback. 2. the dialogue between the telephone requires us to use more information processing power of the brain as sound data compression or background noise, mobile voice and in the outgoing call is not exactly normal, we need to change in the brain. 3. the machine loud noise forcing people to use a larger voice for mobile phone so that it can be heard clearly. 4. If the potential audience a wide enough (for example, each one can hear the phone), the passengers will attempt to say more. In other words, people feel that phone conversation, at least, than on the dialogue among the passengers, but is thicker tone when tanxing also unknowingly increase.
Source: United States Department of Homeland Security Transportation Security Authority, Wikipedia
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