Acquisition of pseudo-noise sequences by digital correlation

Abstract

In this thesis, a new fast pseudo-noise (PN) sequence acquisition algorithm for direct sequence (DS) spread spectrum system is studied. The purpose of this work is to realize the fast PN sequence acquisition system which can be used in various communication systems including ranging systems. The basic concept of the proposed PN sequence acquisition system had been adopted from that of the classical sliding correlator. Mathmatical modeling of the proposed system and its analysis have been done. Also, the candidates of optimum parameters of the system have been selected using the analysis results. Next, computer simulation was performed to find the optimum system parameters among the candidates from the analytical results and to verify the analytical study. In the simulation program development, various kinds of computation reduction techniques have been employed. The results of analysis and computer simulation show that the proposed system yields significant performance improvement over the sliding correlator over the wide range of signal to noise ratio (SNR). Finally, hardware and software for PN sequence acquisition have been developed. In the hardware, two 64 bit digital correlators have been used for real time digital correlation and a Z-80 single card computer (SCC) has been used for the correlation hardware control. To control the high speed hardware with much slower SCC, an efficient method of control has been studied. To test and measure the performance of the developed hardware, Intel TK-80 has been used. The results of hardware performance measure are also presented.