Importance

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Abstract

A transmitter system for transmitting coded message signals on a plurality of channels of which at least one channel to be assigned to each of a plurality of geographical areas. The coded message signals include channel identification information and message information being transmitted in a sequence of coded transmission slots on each of the plurality of channels. The sequence of coded transmission slots are transmitted offset in time such that a particular transmission slot is not substantially simultaneously transmitted on any of the plurality of channels. A receiver capable of receiving the coded message signals during a predetermined coded transmission slot being transmitted on the plurality of channels is also described. The receiver includes a channel selecting circuit responsive to detecting the predetermined channel identification information transmitted during the predetermined coded transmission slot on the predetermined channel, for maintaining reception during the predetermined transmission slot on the predetermined channel. The receiver also includes a memory for storing active channel information for a given geographic area, and the channel selecting circuit is responsive to the active channel information for selecting the reception of only the active channels in the particular geographical area when the channel identification information detected during the predetermined coded transmission slot on the predetermined channel does not match predetermined channel identification information.

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First Claim