System design aspects of a simulcast trunked system

Abstract

Businesses and governmental organizations are researching for means to better manage their resources (energy, labor, equipment, etc.) and thus contribute to operational productivity improvements. Many such organizations are becoming aware of the potentials a radio communication system can afford in the area of assisting resource management. To satisfy the communication needs of major private radio users, an 800 MHz trunked dispatch system offers many system benefits, such as apparent user privacy, simplified radio operation, faster channel access and flexible fleet partitioning. The basic structure of a trunked dispatch system is a co-located configuration; with all the base transmitters, receivers and control equipment resident at a single site. This co-located configuration limits the applications for the user with large radio communication system requirements. The user with communications needs extending beyond the coverage contour of a single base repeater site finds the co-located configuration awkward to implement efficiently to satisfy all the communications needs. Examples of users having large communication needs would include petroleum companies, public utilities, and large municipalities. To address the needs of many such users, a wide area coverage system is developed by merging the concepts of a trunked dispatch system with simulcast transmit techniques. This communication system offers all the features of a co-located trunked dispatch system, but allows the coverage area to greatly extend beyond the single base repeater site to encompass many remote repeater sites. To effectively merge these communication systems, a myriad of technologies is employed. Wide area coverage simulcast communication systems have been previously developed for special applications, thus producing a guide to general areas of concern of a simulcast communication approach. The development of areas of the 800MHz. trunked dispatch simulcast system introduces many areas new to simulcast system development. Previous simulcast systems have dealt predominently with voice communication solely. A trunked system utilizes digital signalling techniques which are affected by the simulcast operation and must be addressed in addition to the expected effects upon the audio voice signalling. The very 800MHz, environment as a host to a simulcast system is an unexplored area. The system concepts and technical issues unique to an 800MHz. simulcast trunked system applications are to be discussed in this paper.