Direct Sequence Spread Spectrum (DSSS) and Code Division Multiple Access (CDMA) transmit data across hostile radio channels by multiplying narrowband information bits by a high-rate pseudorandom noise (PN) chipping sequence. Spreading the signal energy across a broad RF bandwidth depresses its power spectral density beneath the thermal noise floor, conferring severe immunity to narrowband jamming and multi-user interference, which are eliminated upon receiver despreading.