What describes a spread spectrum communications system altering the center frequency of a conventional carrier rapidly?

A spread spectrum communications system that alters the center frequency of a conventional carrier rapidly is known as frequency hopping. This technique involves changing the carrier frequency at predefined intervals, programmed into the system. By rapidly switching frequencies, frequency hopping provides several benefits, including resistance to interference and eavesdropping, as well as improved security for the transmitted signal. It spreads out the signal over a wider bandwidth, which makes it more robust against jamming and allows multiple users to share the same frequency band more effectively.

In contrast, amplitude modulation involves varying the amplitude of the carrier signal without changing its frequency. Direct sequence is another spread spectrum technique where the data signal is modulated with a higher-rate pseudorandom noise signal, but it does not involve rapid frequency changes. Time division multiplexing allows multiple signals to occupy the same frequency channel by dividing the signal into time slots, which is unrelated to varying the center frequency of a carrier.