Noise that satisfies one or more standard tests for statistical randomness. Although pseudorandom noise seems to lack any pattern, it contains a sequence of pulses that repeat after a long period of time or after a long sequence of pulses. Spread spectrum (SS) radio systems modulate the carrier so that it appears as pseudorandom noise to receivers that are either not locked onto the transmitter frequencies or are incapable of generating a pseudorandom code sequence that correlates with the received signal. See also carrier, code, frequency, noise, signal, and SS.