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Redwood City� Pofice <br /> Department System Performance <br /> � — -r - — � - —; — — � — — � - - � <br /> t. ; 01 ; 0 ; 11 ; 0 � �a � <br /> r _ � _ � _ � — • r — r — — D3tc1jI1 <br /> ; 1 ; 0 � ; 01 ; 0 � <br /> � — � — r — � — r — � — — <br /> � 0 � 1 � � � 1 ' 1 ' <br /> r _ � _ � _ �_ � — � — — , <br /> , , � � � � <br /> � � � ' ' ' <br /> Data Out <br /> Although the actual table is much larger,this diagram Pr°v�des a <br /> good example. The original message including CRCs and <br /> protection bits begaII"O l 0011 O 1 00 ..." and is entered across the <br /> top row. For transmission,the bits in the first coi��be <br /> selected,followed by the second column and so on. Thus,the <br /> output message will begin"O1 10 00 ...." and will continue along <br /> the columns of this�ble. <br /> By interleaving bits in the transm�tt��S��'�e likelihood <br /> that bit errors introduced bY RF fades will corrupt adjacent bits in <br /> - the decoded message is drasticallY reduced Th�s Process greatly <br /> �, improves the ability of the RD-LAP algorithms to detect and <br /> correct any bit errors. <br /> This interleaved message is then broken into optimum sized <br /> packets, assigned a sequencing number and transmitted. At the <br /> receiving end,the data packets are assembled in their correct order, <br /> placed in a table v�here the interleav�ng PtO�s is reversed,and <br /> checked and corrected usinS th�C�Cs and p=otection bits. <br /> g�_I,p,p�uses a closed-loop protocol that requires CAD sYstems or <br /> Mobile Data Terminals to acknowledge the delivery of a.message <br /> III this�uay,as Offic,ers in the field or dispatchers at the <br /> Departmentbuilding initiate a.transmission,they also receive <br /> initiatioB of the status of their message <br /> A message accounting scheme Prohibits message loss and prevents <br /> the device user from receivuig duplicate copies of the same <br /> message. A message�ans�tioa number,(separate from the packet <br /> sequence number)along with the ID ofthe initiating device,is sent <br /> with each message as unique ideatification. The receiving device <br /> uses these identifiers to differentiate betw�duplicate copies of ' <br /> � <br /> 3 -.3 � <br /> QM�QR' �t.� w <br /> . .. . . ... . . _..._. . ._..,._ ..... .... ... . <br /> ._._.__. . .__,... ._._. _.._.. <br />