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 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 .