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SECTION 1 '-*'SYSTEM DL . RIPTIONIPERFORMANCE <br />1.4.2 Over -the -Air Protocol <br />Motorola's RD-LAP data transmission standard has been designed to optimize <br />accurate transfer of data over land mobile radio channels. Error detection and <br />correction tecluuques are employed to increase the probability of successful packet <br />-delivery-in the harsh land mobile environment. In addition, data is transmitted at <br />9,600 bps over 12.5 kHz, 821--824 MHz channels. RD-LAP 9.6 provides a two -fold <br />increase over the current MDC 4800 data system. <br />1.4.3 Network Design <br />The City of Santa Ana Police Department's data system design includes a new Radio <br />Network Controller (RNC), an existing single Base Station, and a mix of one -hundred <br />and fifty field devices on one RF channel using MDC 4800 protocol. The installation <br />of the RNC 3000 will allow migration to RD-LAP 9.6 over -the -air protocol in the <br />future. <br />1.4.4 Field Device Performance <br />Another key factor affecting system capacity is the transmitter performanee of the field <br />devices. The ability to quickly key the transmitter enables increased inbound <br />messaging from multiple field devices. The associated parameter is known as <br />Transmitter Turn -On (TTO) time. Lower values for TTO are optimal for increased <br />system capacity. The Vehicular Radio Modem (VRM600) typically performs with a <br />fifteen -millisecond TTO. <br />1.4.5 Customer Message Profile <br />The most important factor affecting the capacity of a data system is the customer's <br />message profile. The message profile describes how the system is being used. <br />❖ What types of messages are sent inbound? <br />❖ How many messages of each type are sent inbound per hour per unit? <br />How many user characters are associated with each inbound message type? <br />❖ What types of messages are sent outbound? <br />:• How many messages of each type are sent outbound per hour per unit? <br />How many user characters are associated with each outbound message type? <br />The length and complexity of the messages transmitted over -the -air will have an <br />impact on the capacity of the system as a whole. <br />OMO IOI�iUL� ConfidentW and Proprietary 1 :. 5 <br />