Abstract: A new digital radio includes codec, vocoder and encryption/decryption processing all on a single integrated circuit chip module. Great flexibility is provided in terms of different operating modes (e.g., encrypt/decrypt only, vocode only, or encrypt/decrypt and vocode). Radio control processor overhead is reduced substantially, because the radio control processor does not need to transfer data between codec, vocoder and encryption/decryption processes and/or components. An internal executive routine within the module handles all vocoder and encryption command and data processing. A special synchronization scheme is provided to synchronize the transceiver modem rate with the speech processing rate. The single-chip speech processing module is sufficiently flexible to allow users to define, write, load and use their own encryption/decryption routines without requiring a new masked ROM.

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.

Abstract: A radio frequency (RF) base station transmitter receiver (transceiver) system includes an audio compression arrangement that compresses a sum of multiple audio signals so that all signals within the sum are equalized to a substantially uniform audio output level despite differences in their input levels. Compression thresholds can be adjusted from a remote location. The RF base station provides audio signal compression using digital signal processing (DSP) techniques such that advanced features (e.g., noise blanking and hard limiting) and flexibility are built into the system. Line audio inputs from several sources are filtered, converted to digital signals, and processed by a digital signal processor (DSP). This DSP provides an audio compression function that selects and applies appropriate gains to the digitized audio signal. The compressed signal is converted to analog form, filtered and routed to a variety of destination such as a RF transmitter modulator or a land line.