VOICE GUARD DIGITAL VOTER FOR MULTI-SITE PST RF TRUNKING SYSTEM

摘要

A voice Guard digital voter system for a mulit-site public service trunking (PST) digitally trunked RF communications system operates on the principle that it is highly likely that messages received during a system redundancy removal period are redundant messages. For a given RF channel, digital receiver is associated with each of multiple sites and receives digital messages reported to it by its associated sites. The multiple digital receivers axe connected to a digital selector via a service request line (FSL) and a serial data line (BSL). Digital receivers calculate a bit error rate code (BERC) for each message they receive. All digital receivers receiving a version of a message are synchronized by the digital selector in response to a request to transmit by one of the digital receivers. The digital receivers wait a delay time corresponding to the BERC they calculates and also responsive to a fixed slot assignment associated with each digital receiver. The digital receiver having the lowest calculated BERC begins first to transmit its message to the selector -- and all other receivers abort transmitting. Bus contentions between digital receivers calculating the same BERC by introducing the additional delay time corresponding to digital receiver fixed slot assignment.