| A basic two way communication system
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| | thirty megahertz to three gigahertz. This
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| consists of base station or base and one
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| | frequency range provides reliable
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| or more mobile units or mobiles. The base
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| | operation within a radius of several
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| station with its control or operation
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| | miles from the base station or repeater
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| point is usually centrally located in a
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| | system. Many radio repeaters are
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| city building. The mobiles communicate
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| | interconnected with the telephone lines
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| with the base by very high frequency or
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| | so that mobile radio operators, equipped
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| ultra high frequency transmitter and
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| | with push button key pads in their
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| receiver sets most often configured as
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| | transceivers, can gain access to the
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| transceivers.
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| | lines.
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| A transceiver is a combination of
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| | An autopatch is a device for connecting
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| transmitter and receiver having a common
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| | radio transceivers to the telephone line
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| frequency control and usually enclosed in
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| | by remote control. Autopatch is generally
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| a single package. Transceivers are used
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| | accomplished through repeaters.
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| extensively in two way radio
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| | A portable telephone is a radio
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| communication at all frequencies and in
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| | transceivers designed for access to an
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| all modes. Another operation that is
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| | autopatch system. Portable telephone
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| usually performed is duplex operation or
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| | resembles handsets with antennas. There
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| simply duplex. It is a form of radio
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| | are two types of portable telephones. The
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| communication in which the transmitter
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| | short ranged variety is called cordless
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| and receiver of both stations are
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| | or wireless telephone. It is designed for
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| operated simultaneously and continuously.
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| | use within a few hundred feet of a base
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| Each station operator can interrupt the
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| | unit. The long range type is similar to a
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| other at any time, even while the other
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| | walkie talkie and its range is limited
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| is transmitting. Therefore a normal
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| | only by the access range of the autopatch
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| conversation is possible similar to that
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| | repeater and transceivers which is
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| over telephone lines. There are no blind
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| | typically ten to twenty miles.
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| transmitters and therefore there is no
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| | A cordless telephone uses a radio
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| need to exchange signals such as over.
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| | connection between the receiver and the
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| Break in operation is a form of radio
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| | base rather that the usual cord. Two
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| communication in which a transmitting
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| | small antennas one at the main unit and
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| operator can hear Mobile telephone is a
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| | other at the receiver allow use of the
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| radio transceivers designed for access to
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| | receiver from six hundred to eight
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| autopat system. Mobile telephones since
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| | hundred feet.
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| they involve radio transmission cannot
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| | A pager is a receive only device,
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| easily be used in some countries without
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| | activated by a two tone signal from the
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| a license from the government. Mobile and
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| | base station that sets off a series of
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| portable telephones usually operate in
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| | audible beeps to alert the carrier to
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| the very high frequency and ultra high
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| | report to the base station or call the
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| frequency radio bands, between about
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| | base station by telephone.
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