Design of a spread-spectrum modulation signal bearing directional information

In this article, we propose a multiple beams spread-spectrum modulation signal transmitted by a Cassegrain antenna for communication and direction-finding applications. The main idea is that a sum beam and two difference beams are transmitted by the Cassegrain antenna similar to the Monopulse technique. According to the beams' radiation pattern, a multiple beams spread-spectrum modulation scheme is designed to modulate the beams' spatial parameters into the transmit signal constellation. In this way, a receiver with a single antenna demodulates the data information and the directional information from the receive signal constellation, simultaneously. Simulation results show that the proposed signal can be applied to the integrated system of communication and direction-finding in a low signal-to-noise ratio environment.