Millions of people use mobile phones in the United States and around the world. These gadgets are great - you can chat with people anywhere!
Now, mobile phones offer an incredible array of features, and new ones are increasing at an alarming rate. According to the mobile phone models, you can: store contact information, production task or making a list, tracking date and set reminders, use the built-in calculator for simple mathematical operation, send or receive E-mail, get information from the Internet (news, entertainment, stock quotes), play games, watch TV, send text messages, integrate other equipment, such as PDA, MP3 player and GPS receiver, mobile browser browse news.
But have you ever thought about how to use your cell phone? What makes it different from ordinary phones? PCS, GSM, CDMA and TDMA what do these terms mean? In this article, we'll talk about the technology behind the phone so you can see how great they really are.
Portable cell phone jammer.For starters, one of the most interesting things about mobile phones is that it's actually a radio - a very complicated radio, but still a radio. Telephone was invented by Alexander Graham Bell in 1876, the wireless communication can trace its roots in the 1880 s of radio invented by nikola tesla (by a young Italian named Marconi in 1894 formally proposed). It is therefore natural that these two great technologies will eventually be merged.
In the dark ages before mobile phones, people really need to install cellular radio communication on their phones. In the wireless telephone system, each city has a central antenna hanger, which may have 25 channels on the tower. The central antenna means that the phone in your car needs a powerful transmitter - enough to transmit 40 or 50 miles. It also means that few people can use a wireless phone - he just doesn't have enough channels.
The genius of the mobile phone system is to divide a city into smaller systems. This can be widely used throughout the city, so that millions of people can use mobile phones at the same time.
A good way to understand the subtlety of a cell phone is to compare it to a CB radio or walkie-talkie.
In a full-duplex radio, two transmitters use different frequencies so that the speaker can talk simultaneously. The phone is full duplex.
Full duplex and half duplex - two intercom and CB radio are half duplex equipment. That is, two people on a CB radio use the same frequency, so only one person can speak at a time. The cell phone is a full-duplex device. That means you use one frequency to speak, another frequency to listen. The caller can speak at once.
Channel - a walkie-talkie usually has a channel, and a CB radio has 40 channels. A typical mobile phone can be on 1664 channels or more communication!
Range - the interphone can transmit about a mile (1.6 kilometers) using a 0.25 watt transmitter. CB radio is capable of transmitting about 5 miles (8 km) using a 5 watt transmitter because of its higher power. Cell phones work inside cells, they can change the cell movement. These cells provide incredible phones. People can travel hundreds of miles with their mobile phones and keep talking because of the cellular approach.
Because cell phones signal jammer and base stations use low-power transmitters, the same frequency can be repeated in non-adjacent communities. Purple cells can use the same frequency again and again.
In a typical American analog phone system, mobile phone operators receive about 800 frequencies for use throughout the city. The carrier cuts off the city in the cell. Each neighborhood is usually about 10 square miles (26 square kilometers).
Each community has a base station consisting of a tower and a small building containing radio equipment. We'll get to the base station later. First, let's look at the cell phone that makes up the cellular system.