MSK Modulation Strategy for Mechanical Antenna Based on Improved Fuzzy PI Controller

As a new ultra-low frequency electromagnetic communication mode, mechanical antenna has high application value in the field of underwater communication and submerged command. Aiming at the problem of low signal-to-noise ratio of rotating permanent magnet mechanical antenna signal radiation magnetic field weakness and the problem of low band utilization of FSK modulation, this paper proposes MSK modulation scheme of mechanical antenna system and its high-performance servo control strategy, establishes the mapping relationship between MSK signal modulation and rotary servo control, and puts forward MSK modulation strategy based on improved fuzzy PI controller by designing fuzzy rules to improve the motor's performance in underwater communication and submergence command. Aiming at the working condition of mechanical antenna system with large transient current and frequent switching of rotational speed, the MSK modulation strategy based on improved fuzzy PI controller is proposed to improve the symmetry of motor acceleration and deceleration by designing the fuzzy rules to eliminate the cumulative error of phase. By controlling the relative position of the motor rotor, it is guaranteed that the rotor phase is always changed in one code element time ±π/2. Finally, the experimental platform of rotating permanent magnet mechanical antenna system is built, and the control performance verification experiment of the servo control algorithm, the modulation signal loading experiment, the penetration ability test under the underground and seawater, and the communication experiment are completed, which verified the feasibility of MSK modulation scheme and servo control strategy.