Abstract: A programmable randomly tunable digital demodulator is provided with a carrier recovery loop and a PN code clock recovery loop each having a programmable digital loop filter coupled in series therein. Each digital loop filter is controlled by a timing control which is capable of controlling the carrier frequency tuning and the PN tuning frequency under the control of a microprocessor. A replica PN generator is programmed to produce an epoch signal when the transmitted carrier frequency and/or chipping rate is varied in a pseudorandom manner and is coupled to the timing controls so that the modulator replicates the received variable rate signals.