Abstract: The present invention uses digital values of MSK-like waveshapes which can be stored in a storage media such as a ROM and then output in a prescribed fashion such as in phase quadrature through the use of an addressing technique to the ROM. The digital values, each of N bits, are then multiplied in quadrature times a data representative signal which is divided into phase quadrature components. These N+1 bit products are summed to produce a composite digital signal representing analog bipolar values. A digital-to-analog conversion provides the modulated analog output signal.

Abstract: A multipath diversity spread spectrum communications receiver will enhance system performance over communication channels with distortion caused by multipath and fading effects. The multipath diversity receiver utilizes decision directed coherent integration with post detection correlation techniques for performance enhancement. The receiver also incorporates a fast attack, fast release automatic gain control to process noncontinuous wideband spread spectrum signals which are subject to fading and multipath effects.

Abstract: Both wide-band and narrow-band noise suppression can be achieved by the disclosed signal normalizer in which the properties of hard limiting and adaptive control weights are fully utilized.

Abstract: A radio signal is applied to an in phase detector channel and a quadrature phase detector channel. Each detector channel includes, in cascade arrangement; an in phase downconverter means for downconverting the received radio signal to a baseband signal; a sampling means for sampling the baseband signal at a predetermined rate; and a matched filter means matched to the symbol waveform and wherein the sample pulses are stored over a predetermined period of time that corresponds to two data symbols. The sum of the pulses for the first data symbol and the sum of the pulses for the second data symbol are compared to determine if there has been a phase reversal between the two data symbols. The outputs of the in phase and quadrature phase channels are summed, which results in demodulation of the encoded data.

Abstract: A single sideband signal can be demodulated by using sampled data techniques. An intermediate frequency (IF) radio signal is split into two branches and is sampled by two sample and hold devices; each sample and hold device operates at a rate that is not only a submultiple of the carrier frequency, but is also at least twice the information bandwidth. Prior to, or during sampling of one branch (the quadrature branch), a Hilbert's transform is performed upon the IF signal which results in the output of the two sample and hold devices being in phase quadrature. A phase shift of 90.degree., using a baseband finite impulse response Hilbert's transform filter, is performed upon the output signal of the quadrature branch's sample and hold device. The sum of the inphase sampled signal and the filtered quadrature phase sampled signal produces the demodulated lower sideband while the difference between the two produces the demodulated upper sideband.

Abstract: A modulating system using a surface acoustic wave device for receiving impulses and providing, as an output, shaped carrier signals for transmitting data. The preferred embodiment uses impulses of positive and negative polarities to provide minimum shift keyed modulated output signals wherein the carrier frequency is an odd one-quarter multiple of the repetition rate of the impulses.