Measured Noise Performance of a Data Clock Circuit Derived from the Local M-Sequence in Direct-Sequence Spread Spectrum Systems

摘要

An improved method for deriving the timing information required for data recoveryin the receiver of direct-sequence spread spectrum systems was implemented in hardware. This method uses a priori knowledge of the spreading sequence and its relation to the transmitted data to determine the precise beginning and end of data bits in the received signal. Testing of the hardware built for this research is concerned primarily with the performance of the circuit designed to provide the timing required to implement an integrate and dump circuit as a means of data recovery. A conclusion of this research effort is that a method exists for deriving the timing information required for data recovery from the locally generated m-sequence in the receiver. This method appears to be superior to alternative methods since the reference timing is derived from the locally generated m-sequence and is therefore isolated from the effects of additive noise in the channel. In addition to this improvement in noise performance, the new method is independent of transitions in the data stream which permits design flexibility for voltage representation of bits.