Explanation: Frequency hopping spread spectrum (FHSS) systems achieve spectrum spreading by rapidly changing the carrier frequency of a signal over a wide range of frequencies. The sequence of these frequency changes, or "hops," is determined by a pseudo-random code known to both the transmitting and receiving stations. This rapid, pseudo-random alteration of the center frequency across a list of available channels is the defining characteristic of FHSS. Direct sequence spread spectrum (DSSS) is a different technique where the data stream is multiplied by a high-speed pseudo-noise code, spreading the signal across a wide bandwidth *without* changing the carrier frequency. "Time-domain frequency modulation" and "frequency compandored spread spectrum" are not recognized terms for this method of spread spectrum communication.