Abstract: A frequency down-converter down converts an input signal having a frequency in a given bandwidth and a frequency up-converter up converts the down converted input signal and imparts a doppler shift to the up converted signal to generate an output signal having a frequency with doppler shift in the given bandwidth.

Abstract: A voltage controlled oscillator has coupled thereto N capacitors in different permutation under control of an N stage binary counter and a counter drive signal enabling the generation of signals having 2.sup.N discrete frequencies. A phase locked loop is employed to stabilize each of the 2.sup.N frequencies. This loop includes a mixer coupled to a harmonic generator and the output of the oscillator. The mixer output is applied to a crystal filter whose output is phase compared with a reference signal and the resultant output is employed to stabilize the oscillator.

Abstract: The correlator disclosed herein detects in a stream of input pulses a plurality of sequences of time spaced signals, each of the plurality of sequences having a different one of a plurality of pulse repetition intervals disposed within a given pulse repetition interval range. This is accomplished by clocking the input pulses into a first shift register by a first clock pulse having a given frequency. N groups of n bistable stages (N being an integer greater than one and n being an integer greater than zero) are disposed at different spaced time positions along the first register corresponding to the pulse repetition intervals and the pulse repetition interval range. First logic circuitry is coupled to each of the N groups of n stages to provide an output pulse when the time spaced pulses of the plurality of sequences of time spaced pulses are simultaneously present at appropriate ones of the n stages of a given number of the N groups of n stages.