Code acquisition by binary autodirective search

Abstract

This paper presents a new method for rapidly acquiring code synchronization in direct sequence spread spectrum communication systems. Traditional search methods look for code synch by sequentially stepping the phase of a locally generated copy of the spreading code and examining the result of correlating that code with the received signal. In contrast, the non-sequential binary autodirective method progressively discards half of the total remaining code uncertainty space with each decision. Decisions are based on correlating the received signal with a succession of locally generated waveforms; the waveforms are constructed such that the correlator output is a signal which indicates whether or not the phase of the locally generated code has been successfully advanced to within half way of achieving synchronization. This paper lays out in detail how the new method works, presents a preliminary analysis of the system's performance, and briefly addresses implementation issues.<>