Advice 1: What frequencies cell phones work

Mobile communication systems worldwide use a wide range of frequencies. They use UHF waves whose length ranges from 10 cm to 1 m. the range includes wave with a frequency of from 300 MHz to 3 GHz.
Cell phones Russia operate on frequencies of 900 MHz and 1800 MHz
The same frequency band is also used by television, Wi-Fi and Bluetooth. Among the range of frequencies are those which were allocated specially for mobile phones.

Historically, the radio waves used for mobile communication systems in the Americas, Europe, Africa and Asia, different from each other.

Standards technology and frequency

The first technology standard used in the U.S. for commercial use was AMPS with the 800 MHz band. In the Nordic countries was first introduced technology NMT-450, the range of which was 450 MHz.

Along with the growing popularity of mobile phone manufacturers are faced with a problem: they could not provide service to a large number of people. They had to develop existing systems and introduce a new standard with a different frequency range.

In Japan and some European countries, the standard TACS with a range of 900 MHz. The GSM standard which replaced technology NMT-450, also used the 900 MHz range. The growth of demand and market of cellular telephones, providers have obtained licenses to use 1800 MHz band.

Lower frequencies enable service providers to cover areas of a larger area, and higher frequencies offer the possibility of providing communication to a larger number of customers in the territory of a smaller size.

Modern standards of technology

The current generation of mobile devices operates mainly on the GSM standard. Also gaining popularity UMTS. In some countries apply technology formats ELT, 3G, 4G.

Each format or standard uses a frequency band of two frequencies. Low frequency range and communicates information from the mobile device to the station, and the high – from the station to the mobile.

A standard GPS phones cover three different frequencies: 900, 1800, 1900 MHz or 850, 1800, 1900 MHz. This so-called phones are tri-band or Quad-band device. With this phone comfortable to travel the world, and it does not require replacement when
moving to another country.

Mobile networks of different formats can use the same frequency. Such, for example, 800 MHz band, used at least in four different formats.

The amount of frequencies available for use by the mobile devices is limited. This should be considered when the number of users will increase. This means that the base station can provide a limited number of people, and communication networks need to constantly expand.

Cell phones major service providers in Russia operate at frequencies of 900 MHz and 1800 MHz. The MegaFon, Beeline, MTS use both range and BODY 2 only 1800 MHz band.

Advice 2: How does wireless mouse

Today, wireless mice are widely demanded and popular gadgets that you can use with computer and laptop. However, some people don't understand how it works – because the wireless mouse does not require use of any wires.
How does wireless mouse

Work wireless mouse

Most wireless mouse communicates with the computer using radio frequency communication, to establish which necessary components such as receiver and transmitter. Using the default mouse transmitter transmits electromagnetic signals that report information about the pressed buttons and mouse movements. The receiver connects to the computer, receives the signals of the mouse and passes them to the operating system driver wireless mouse.
The receiver can be either built-in or a separate device connected to the computer in the form of a special card inserted into the expansion slot.

The same principle is used by many electronic devices – cell phones, wireless networks, drives, garage doors, remote controls and so on. However, unlike infrared, which are those devices, RF communication does not require the presence of the mouse and receiver on an available distance from each other. The signal transmitter of the gadget passes easily through obstacles in the form of a computer monitor or table top.

Sync wireless mouse

As in most modern computer mice, wireless models use no ball and an optical system that significantly improves the accuracy of the gadget. In addition, the optical system allows the user to use a wireless mouse almost on all surfaces, which is very important for the device not connected to computer by cable at least for some time.
Another advantage of radio frequency communication – the minimal energy consumption of the radio transmitters and receivers, which also are lightweight, inexpensive and can run on batteries.

Sync wireless mouse is necessary for the interaction of the transmitter with the receiver, which must operate on the same channel that represents a set of identification code and the frequency. Thanks to the synchronization prevents the occurrence of interference provoked by other wireless devices and by unauthorized sources.

Every manufacturer equips its wireless mouse – some models (more expensive in the overall ranking) are sold already synced, and some need to synchronize automatically by pressing certain buttons on the device. Protection of data transmitted with the mouse to the receiver, carry out the encryption mechanisms or the technology of frequency hopping.
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