Spread Spectrum Multiplexed Noise Codes

The contents of this paper comprises a treatise on spread spectrum multiplexed noise codes. Multiplexed noise codes are codes formed with mate code pairs which when orthogonally multiplexed, transmitted, and detected in a matched filter possess an impulse autocorrelation function (i.e., noise like codes which compress to a single impulse containing no sidelobes). The fundamental requirement for achieving this desirable result is that the autocorrelation function of the two codes forming a mate pair must be of equal magnitude and opposite sense for all values of time outside of the main lobe. The various fundamental concepts which define the requirements for obtaining lobeless compression, an orthogonal noise code subclass, and basic general code expansion concepts are described and theoretically verified. In addition, a relatively complete coverage of the various unique attributes inherent in multiplexed noise codes are disclosed. In essence, a practical unified theory and explanation of these codes is presented to teach the principles involved and illustrate the magnitude of the gains that are realizable from codes that are capable of compressing to a lobeless impulse and which are available in abundance. The theoretical treatment demonstrates that the concepts and applications are all technically sound. Utilizing the various concepts established, an orthogonal subset of multiplexed noise codes (32 bit mate pair codes) was implemented actively using shift registers and tested in appropriate test configurations to verify that the theoretical performance can be obtained with practical hardware.