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Redwood City Police <br /> Department System Performance <br /> '� SYSTEM PERF'�RMANCE OVERVIEW <br /> � <br /> This Motorola IViobile Data System wilI provide an important <br /> digital communications link between City of Hillsborough Police <br /> Department OfficeTS,dispatchers, and the Department's data <br /> resources. Whereas the System Description section of this <br /> proposal listed the location, composition and basic functionatity of <br /> the equipment in this system,this section serves to show how this <br /> equipment will perform in terms of: <br /> • Radio�ata Link Access Protocol <br /> • System Capacity <br /> • Radio Infiastructure Coverage <br /> RADIO DATA-LINK ACCESS PROTOCOL <br /> To accomplish the transfer of all mobile data messaging <br /> possibilities, Motorola's Radio Data-Link Access Protocol (RD- <br /> LAP) protocol has been designed to optimize accurate transnussion <br /> of data over a radio channel. Data is transmitted at 19,200 bps <br /> over an 806 MHz channel and appmximately one fourth of the <br /> - information sent consists of error detectian and correction code to <br /> �. provide optimum, single transmission, error free messages. The <br /> result is the fastest radio data rate available today with bit error <br /> rates less than one percent at 20 dB quieting received signal levels. <br /> Successfvl data transfer is possible even whea received signal <br /> strengths are less than those required for voice systems. Because <br /> of this, data system users experieace coverage performance that <br /> meets or exceeds that found in voice systems using equivalent <br /> radios. The three main topics that the RD-LAP protocol standard <br /> specifies are the method by which data is encoded,the type of data <br /> signaling and the means by which the radio channel is organized. <br /> The efficiency vuith which an encoding algorithm can successfully <br /> correct bit ermrs depeads on the type and length of error in the <br /> message:. Conseqne�ntly,a single figure representing error <br /> correction capability is not possible to state without specifying <br /> message length,the number of bit eimrs,the number of adjacent <br /> bit errors in the data.pattera and the types of bits tha.t are corrupted- <br /> One indication of Motorola's algorithm suc,cess in correcting <br /> message errors is that,depending on the factors listed above, over <br /> 20%of amessage can be coirupted and yet still be completely <br /> corrected. <br /> �: . <br /> QMOroRO�a • 3 - 1 <br /> . _. _ _ _._w _ <br />