A Low-Rate Wireless Spread-Spectrum Communication Technique using Linear Step FM Signal

A low data-rate communication technique using linear step frequency modulated (LSFM) signal is presented. When the carrier frequency offset (CFO) between the transmitter and the receiver is significant comparing to the symbol rate, the techniques using normal signaling waveforms with matched filtering become infeasible. In this scenario, wideband chirp (linear FM) signal is feasible because of its favorable characteristics in ambiguity function. However the fully digital implementation of the matched filter for the chirp signal is not economic. In this paper, we propose the use of a linear step FM signal, which has similar characteristics as a chirp signal, and an efficient hardware structure in the digital implementation of the corresponding matched filter. Keywords—Chirp, Linear Step FM, Low-Rate