Handheld transceiver with frequency synthesizer and sub-audible tone squelch system

摘要

A handheld transceiver providing separate selective communications links for transmission and reception on a single carrier frequency by means of independent carrier and sub-audible tone frequencies in transmit and receive modes. A carrier frequency synthesizer functions as a local oscillator and direct FM modulator, and a Continuous Tone-Coded Squelch System (CTCSS) generates and detects sub-audible tones that are transmitted simultaneously with voice information on a carrier wave. The carrier frequency synthesizer and the CTCSS tone detector/generator operate at frequencies independently determined by data stored in a programmable read only memory such that each channel can be programmed to have a unique carrier and CTCSS tone frequency in both transmit and receive modes.