Abstract: A microcomputer within a duplex RF transceiver operates in an interrupt-driven manner to simultaneously encode and decode CTCSS signalling (with one microcomputer interrupt service routine being devoted to CTCSS encode, and another microcomputer interrupt service routine being devoted to CTCSS decode). Such encoding and decoding of CTCSS signalling is accomplished using minimal external control hardware (e.g., two flip flops and an inexpensive conventional multipurpose counter/timer chip). The resulting arrangement is inexpensive, reliable and requires only a few components in addition to the appropriately programmed microcomputer in order to provide simultaneous encoding and decoding of CTCSS signals in a full duplex RF transceiver context.

Abstract: A LAN multi-node generic digital signal communications link within a radio frequency (RF) base station system communicates control signals within and between base stations. The generic digital signal link eliminates the use of multiple lines for respective functions by using the same generic communications interface for various different functions. By using such a generic digital signal link for inter and intra base station communications, RF and auxiliary control become standardized--reducing complexity in the product, in the documentation and in field repair techniques.

Abstract: A digital FM base station radio having a dedicated digital signal processing (DSP) board operates on audio signals from RF links and land lines. The DSP board detects, filters and generates tones and communicates information regarding these tones to a controller microprocessor on the central control board for the radio.