Analysis and Optimization of Direct Sequence Spread Spectrum Scheme for an Unmanned Aerial Vehicle PPM Control Signal

Binary pulse-position modulated (PPM) control signal is widely used in remotely controlled unmanned aerial vehicles. It consists of data frames, which contain a synchronizing pulse followed by a number of shorter pulses equal to the number of channels N. In this paper we present analysis and optimization of direct sequence spread spectrum (DS-SS) scheme for PPM control signal protection. That scheme uses (N+1) pseudonoise (PN) sequences: one of them (PN0) is assigned to the synchronizing pulse while the each of the remaining N sequences (PN1, PN2,..., PNn) corresponds to the appropriate channel. At the receiving side, the set of (N+1) passive correlators is used to detect respective PN sequences and to reconstruct data. One-level and two-level detection are considered. Threshold settings optimization is based on the Neyman-Pearson procedure. As an additional performance measure we introduce probability of corruptive false alarms. Numerical results are presented.