Application of Wavelet Transform Techniques to Spread Spectrum Demodulation andJamming

摘要

This project has investigated the application of wavelet methods in spreadspectrum communications. Use of the wavelet transform as an alternative to the short-time Fourier and quadratic time-frequency transforms for measuring critical parameters of intercepted slow frequency hopping communication signals has been explored. Direct application of the wavelet transform was found to not offer performance advantages over the Fourier transform in this application. However, use of the wavelet transform in conjunction with Fourier methods provided an efficient hybrid framework for precise measurement of hopping times and frequencies. A new approach to multiple-access spread spectrum communications was also developed in this project. This approach employs orthogonal wavelets as symbols for encoding digital communication signals. Several users can transmit simultaneously in the same medium using channels defined by wavelet scale in much the same way that channels are defined by frequency in traditional frequency division multiple access. Appropriate choices of wavelet symbols make the transmitted signals robust with respect to detection and jamming.... Wavelets, Spread spectrum communication systems.