Abstract: A spread spectrum communications system is described for recovering data from a signal having a first carrier frequency modulated by one of at least four phase modulations, each phase modulation orthogonal to one another and the signal further modulated by a predetermined spreading function incorporating a frequency synthesizer for generating a plurality of frequencies, including one of the phase modulations, a plurality of mixers, a combiner, a broadband convolver, a second combiner coupled to a reference signal generator for generating respective orthogonal modulations on spaced apart carrier frequencies, a power divider coupled to the output of the convolver and filters each having a frequency passband for recovering or separating the output signals of the convolver. The invention overcomes the problem of additional hardware complexity to accomodate Walsh orthogonal functions and of requiring a plurality of broadband convolvers to decode a plurality of orthogonal modulations of lesser bandwidth.

Abstract: A convolver having at least a first interdigital transducer for generating a first surface acoustic wave in response to an input signal and a second interdigital transducer for generating a second surface acoustic wave counter to the first surface acoustic wave in response to a time reversed-time multiplexed reference signal. A segmented summing bus having a plurality of fingers extending into the interaction region of the first and second surface acoustic waves generates a plurality of samples indicative of the convolution of the first and second surface acoustic waves. The convolver also includes a pair of acoustic horns, one disposed between the segmented summing bus and each of the interdigital transducers and a ground bus having a plurality of filler segments extending intermediate the fingers of the segmented summing bus.

Abstract: A digital minimum shift keyed modulator (MSK) has been described incorporating a code generator for generating a plurality of bits in series representative of a spreading function, an Exclusive OR circuit for multiplying two successive bits, a memory for holding predetermined constants, timing circuitry, a digital-to-analog voltage converter and a bandpass filter. The invention overcomes the problem of variations over frequency and temperature associated with previous MSK modulator designs.

Abstract: A minimum shift keyed reference signal generator is described (FIG. 3) incorporating a shift register, for holding a spreading function, a first and second memory for holding in-phase and quadrature weights, a counter for addressing the first and second memory and first and second Exclusive OR circuits for combining the weights when addressed by the counter with the spreading function held in the shift register. A minimum shift keyed correlator is described (FIGS.

Abstract: A spread spectrum communication system is described for decoding data from a signal having a carrier frequency and at least one of a plurality of predetermined orthogonal modulations thereon incorporating a frequency synthesizer for generating a plurality of frequencies, a plurality of mixers, a combiner, a broadband convolver, a second combiner coupled to a reference signal generator for generating respective orthogonal modulations on spaced apart carrier frequencies, a power divider coupled to the output of the convolver and filters each having a frequency passband for recovering or separating the output signals of the convolver. The invention overcomes the problem of requiring a plurality of broadband convolvers to decode a plurality of orthogonal modulations of lesser bandwidth.

Abstract: Digital codes, each of which is comprised of a series of equally spaced pulse positions bracketed by framing pulses are passed through a delay line having a plurality of taps. The taps are connected in a gating structure which extracts only valid codes and suppresses garbled and phantom codes.

Abstract: The positive portion of the differentiated negative envelope of a detected radar return signal is divided into range cells. The first range cell is taken and doubled to provide a first and succeeding range cell to comprise a Doublet. The Doublets are integrated in a sliding window detector and beam split to supply the target coordinates.