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. . . (JJJj37 2.4 RADIO REPEATERS Where radio signals from remote transmitters cannot get directly to a base station one or more radio repeaters are required. Data messages are then transmitted from remote sites to a repeater which relays the data to the base station or to another repeater. Without high performance and reliable repeaters acquisi tion systems using VHF radio ,...auld not be radio repeaters have again extended the state"of reliable signal delivery through difficult radio large scale data possible. Sierra/Misco .the--art to provide pathways, The radio repeater consists of 5252 Smart Repeater DB224 Omni Antenna 5051C RG8 Coaxial Cable MODEL 5252 SMART REPEATER The 5252 is an intelligent store and forward repeater. As a store and forward repeater the 5252 routinely 'listens' for incoming data, When a valid data message is received the message is momentarily stored while the radio receiver is turned off and the radio transmitter is turned on, The data message is then released from storage and fODtarded to the base station or to the next repeater. Turning off the radio receiver before retransmitting the data message eliminates intermodulation that often occurs between the repeater receiver and transmitter. When the repeater receiver is left on during retransmission some of the radiated energy is picked up by the receiver. even ~hen the incoming and outgoing frequencies are different The receiver becomes 'preoccupied' by the outgoing radio signal and is less sensitive to ne\/ incoming data Valid but weak signals from marginal radio paths may be misned. Sierra/Misco has increased the sensitivity of the Model 5252 to incoming data by 300 to 500 percent using the ntore and forward technique. Previously unrecognized signals now get through with ease The Model 5252 can be used as either a single or two frequency repeater Since intermodulation problems are eliminated by the store and forward technique the same radio frequency can be used for both receiving and transmitting Radio frequency allocations can be more efficiently managed. Further improvements in the performance of the 5252 Repeater come from advanced digital signal processing techniques used to better discriminate valid data signals from other radio traffic. A microprocessor in the 5252 is used to determine if a received message is valid If the message is valid it is prepared for retransmission If not the message is ignored All extraneous radio traffic is stopped by the repeater The base station or the next repeater are no longer burdened with unwanted and unnecessary radio traffic.