DUAL RECEIVE OPERATION FOR TRUNKED/DATA SYSTEMS
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2002-Feb-04
INTRODUCTION trol occupy different, independent channels and the subscriber radio is constructed such that it is able to liunked radio systems are more and more frequently access both the control and the data channels as long as being called upon to provide for data services to and it is not involved in a voice call. from the trunked radio subscribers. These services are currently provided in one oftwo ways: Either data mes- CLASSIC SOLUTION sages are treated much lie voice messages, having a channel assigned for each data message session; or, all Clearly, the interactions the limitations of those inter- data is handled on a specific data channel with voice actions between trunked voice operation and data oper- radios either autonomously switching to the data chan- ation could be eliminated by completely separating the nel when initiating a data message or being directed to trunked voice and data systems. This requires the use of the data channel when receiving a data message. In either entirely separate subscriber radios for the two functions, case, data throughput is seriously compromised due to and expensive solution unacceptable to many customers. the lack of rapid access to the subscriber units for data traffic. Furthermore, priority voice system access may Separation ofthe receive functions for trunked voice be disrupted by long data messages, keeping the and data in such a way that the trunking system control subscriber unit out of contact with the control channel information and the data channel may both be received for long periods of time. at the same time will provide nearly all the benefits of separate radios, particularly in systems where the voice The ideal case for the trunked system is for the and data traftic load is moderate. subscriber radio to have access to and be accessible on the control channel any time it is not involved in a voice To allow independent reception of two different sig- call. The ideal case for the data system is for the subscriber nab, at least some portions of the receiver functions must to remain on the data channel at all times. This ideal be duplicated. A classic, hardware based implementa- may be approached by a system in which data and con- tion is depicted in Figure 1.