Mobile Phone

IN THE EARLY 1990s. THE MOBILE PHONE (or
cellphone) was a rare luxury, but in recent years it
has outsold almost every other electrical gadget
as a professional tool, domestic convenience, and
even a fashion accessory. Mobile phones have also
generally shrunk in size, due to improvements
in rechargeable batteries, which now store more
electricity for longer in a smaller package, and
to smaller, more efficient electronics that use less
electricity. A "mobile" is basically a low-power
radio receiver-transmitter, plus a tiny microphone
to convert sounds into electrical signals, and a
small speaker that does the reverse. When the
mobile phone is activated, it sends out a radio signal
that is answered by nearby mast transmitter-
receivers. The phone locks onto the clearest signal
and uses this while within range the range of
each transmitter is known as a cell). The phone
continuously monitors signal strength and
switches to an alternative transmitter when
necessary. The phone's liquid crystal display
(LCD) shows numbers, letters, symbols, and colour
pictures. Newer models have a larger screen for
more complex colour images, and commonly
incorporate a camera, radio, and MP3 functionality.
Smartphones, which are increasingly widespread,
contain additional software and more may be
downloaded. Smartphones typically offer
Internet and email access, PDA-like functions, and may even contain GPS
navigation software.