SAW device implementation of a weighted stepped chirp code signalfor direct sequence spread spectrum communications systems

摘要

This paper introduces a new weighted stepped chirp code signal forndirect sequence spread spectrum (DS/SS) communications systems. Thisncode signal uses the truncated cosine series functions as the chipnfunctions, and it is the result of discretizing a continuous wave (CW)nchirp that results in enhanced performance versus a pseudonoise (PN)ncode and equivalent performance and easier implementation than a CWnchirp. This code signal will be shown to have improved compression ration(CR) and peak sidelobe level (PSL) versus a PN code with identical codenlength and chip length. It also will be shown to have a similar CR andnPSL compared to a CW chirp with identical pulse length and frequencyndeviation. The code signal is implemented on surface acoustic wave (SAW)ndevices that will be used as the code generator at the transmitter andnthe correlator at the receiver. The design considerations for the SAWndevice implementation of the code signal are discussed, including theneffects of intersymbol interference. Experimental data is presented andncompared to the predicted results for 8 different SAW devices examiningnthe effects of code length (9 or 13 chips), weighting (uniform,ncosine-squared, and Hamming), and sampling on the performance of thencode signal