Accession Number : AD0020524

Title :   CORRELATION DETECTION USING STORED SIGNALS

Corporate Author : MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB

Personal Author(s) : Green,P. E. , Jr

Report Date : AUG 1953

Pagination or Media Count : 1

Abstract : The problem of sending a message, consisting of a sequence of symbols, through additive white Gaussian noise is discussed. The NOMAC system, a type of communication system employing noise-like signals and cross-correlation detection, is described as an answer to this problem. In order for desired operating characteristics to be achieved, synchronized reference copies of the signaling wave forms must be available independently at both transmitter and receiver. Preparatory to investigating ways of storing the reference signals, a study was made of the degree of synchronization required and the amount of distortion which can be tolerated. The nature of the correlation operation suggested storage either as the impulse response of a matched filter or as a function time. The process of storage as a function of time appeared more practical. An experimental system, deriving its stable time base from a crystal oscillator and producing signals of required characteristics, were devised. In an effort to judge the usefulness of NOMAC systems, the effect of quasi-stationary multipath conditions was analyzed. The superior performance with multipath of either storage type system and the advantage of using wide-band signals were demonstrated. Results indicated that signal storage systems of the type developed experimentally are practical and that further investigations should proceed along these lines and toward the development of a practical matched-filter systems.

Descriptors :   BROADBAND, COMMUNICATION AND RADIO SYSTEMS, CORRELATION, CROSS CORRELATION, CRYSTAL OSCILLATORS, DETECTION, DISTORTION, GAUSSIAN NOISE, MATCHED FILTERS, MULTIPATH TRANSMISSION, NOISE, OPERATION, PULSES, RESPONSE, SIGNAL PROCESSING, SIGNALS, STABILITY, STORAGE, SYNCHRONISM, SYNCHRONIZATION(ELECTRONICS), TIME, WAVEFORMS, WHITE NOISE.

Distribution Statement : APPROVED FOR PUBLIC RELEASE