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Orange County Emergency Management, North Carolina <br />Final VIPER Anal sis Re ort Au ust 20, 2004 <br />2.2.2 RF Linked Dispatch <br />Description <br />RF linked dispatch requires no connection between a PSAP and the Zone <br />Master equipment at Raleigh. A number of RF control stations are <br />installed at each PSAP and connected to non-trunked console switch <br />equipment located at the PSAP. The RF control station antennas would be <br />directed to the closest VIPER trunked radio site having the greatest <br />channel capacity. Trunked Unit ID and emergency status from the VIPER <br />trunked system to the console display would require a translator computer <br />and RF control channel monitor. <br />Advantages & Disadvantages <br />Advantages are no telecommunications links to the Zone Master are <br />required. All console equipment needed for dispatching is co-located at <br />the PSAP. <br />Disadvantages are that NFPA 1221 requirements are difficult to meet with <br />this approach. There is a possibility of blocked radio calls not reaching. the <br />PSAPs. In addition, the telecommunicator cannot preempt field units. <br />Blocking occurs when the number of calls directed to a site exceeds the <br />site's call capacity. The number of RF control stations installed and the <br />channel capacity of a VIPER trunked radio site supporting dispatch limit <br />the number of simultaneous calls available to be monitored at a PSAP. <br />VIPER is a multi-site design and traffic is active at a trunked radio site <br />relative to the talk groups logged into a site. The RF linked dispatch <br />approach forces all calls to be assigned to the site supporting the PSAP <br />simply due to the consoles monitoring talk groups associated with other <br />areas of Orange County. <br />Section 2 -Technical Description of VIPER Network <br />,~«s ~ Page 8 of 43 <br />_,, <br />