Base station

Two GSM mobile phone base stations disguised as trees in Dublin, Ireland.

Close-up of a base station antenna in Mexico City, Mexico.

A typical consumer-grade CB base station.

A professional rack-mount iDEN Base Radio at a Cell Site.

The term base station can be used in the context of land surveying, wireless computer networking, and wireless communications.

1 Land surveying
2 Computer networking
- 2.1 See also
3 Wireless communications
4 External links
5 Categories

Land surveying

In the context of land surveying, a base station is a GPS receiver at an accurately-known fixed location which is used to derive correction information for nearby portable GPS receivers. This correction data allows propagation and other effects to be corrected out of the position data obtained by the mobile stations, which gives greatly increased location precision and accuracy over the results obtained by uncorrected GPS receivers.

Computer networking

In the area of wireless computer networking, a base station is a radio receiver/transmitter that serves as the hub of the local wireless network, and may also be the gateway between a wired network and the wireless network.

Wireless communications

In radio communications a Base station is a two-way radio installation in a fixed location, used to communicate with one or more mobile or portable radio transceivers. They are typically used by low-power two-way radios such as mobile phones, portable phones and wireless routers. For example, the signals from one or more mobile telephones in an area are received at a nearby base station, which then connects the call to the land-line network. In the case of a portable phone, the connection is typically direct to a land line.

Base stations can be local controlled or remote controlled. Local controlled base stations are operated by front panel controls on the base station cabinet. Remote control base stations can be operated over tone- or DC- private line telephone circuits or radio links.

Terms for base stations in US licensing jargon

Base stations are sometimes called control or fixed stations in US Federal Communications Commission licensing. These terms are defined in regulations inside Part 90 of the commissions regulations. In US licensing jargon, types of base stations include:

A fixed station is a base station used in a system intended only to communicate with other base stations. A fixed station can also be radio link used to operate a distant base station by remote control. (No mobile or hand-held radios are involved in the system.)
A control station is a base station used in a system with a repeater where the base station is used to communicate through the repeater.
A temporary base is a base station used in one location for less than a year.
A repeater is a type of base station that extends the range of hand-held and mobile radios.

Emissions issues

While low levels of radio-frequency power are usually considered to have negligible effects on health, national and local regulations restrict the design of base stations to limit exposure to electromagnetic fields. Technical measures to limit exposure include restricting the radio frequency power emitted by the station, elevating the antenna above ground level, changes to the antenna pattern, and barriers to foot or road traffic. For typical base stations, significant electromagnetic energy is only emitted at the antenna, not along the length of the antenna tower.

Because mobile phones and their base stations are two-way radios, they produce radio-frequency (RF) radiation (that's how they communicate), and they expose people near them to RF radiation giving concerns about mobile phone radiation and health. Hand-held mobile telephones are relatively low power so the RF radiation exposures from them are generally low.

The consensus of the scientific community is that the power from these mobile phone base station antennas is too low to produce health hazards as long as people are kept away from direct access to the antennas. However, current international exposure guidelines (INCIRP) are based largely on the thermal effects of base station emissions. Some scientists have questioned whether there are non thermal effects from being exposed to low level RF such as are transmitted from mobile phone base stations. Such 'non-thermal' effects include how the actual frequencies interfere with the human brain and all other cells in the human body. Sources for consideration can be found here.