Frequency-Coded Signals with Low Sidelobes in Central Zone of Autocorrelation Function
Kapitel i bok, 2011
This chapter presents a new class of signals based on frequency coding sequences that may be constructed by means of perfect difference sets. These sequences give rise to frequency-coded signals of a specific structure characterized by nonuniform distribution of the number of subpulses over the frequencies. Such a structure allows achievement of considerably lower sidelobes in the vicinity of the main lobe of the time autocorrelation function relative to those exhibited by Costas signals without using weighting functions. It is clear that unlike the weighting, this approach doesn’t result in signal-to-noise ratio degradation although the main lobe broadening still remains. In addition these new signals exhibit thumbtack ambiguity functions with relatively low sidelobes over a wide region of the time-frequency plane. The chapter is organized as follows. In Section 2, the structure of a new class of multifrequency signals is described. Next, a simple algorithm, which employs the fundamental property of perfect difference sets , for the design of the frequency coding sequences is considered in Section 3. Section 4 presents some results of analytical and numerical investigation of the autocorrelation and ambiguity functions of the proposed signals.