Mobile Underwater Acoustic Communication System for Small Underwater Unmanned Platform

Abstract

Mobile underwater acoustic communication channels have the typical characteristics of multipath and Doppler dual expansion, which seriously affects communication performance. In particular, the equipment of small underwater unmanned platforms in the field of underwater special operation has the characteristics of variable navigation state, multi-shallow sea application, and low transmission power under limited power consumption, resulting in variable Doppler, serious multi-path, and low signal-to-noise ratio (SNR), which poses great challenges to traditional mobile underwater acoustic communication schemes. In this study, a mobile underwater acoustic communication scheme for small underwater unmanned platforms in a special operation field is proposed. In this scheme, the analog/digital conversion sampling rate is adjusted by a direct digital frequency synthesizer chip, and real-time Doppler compensation is realized in the hardware. Combined with direct spread spectrum sequence modulation, the anti-multipath performance is improved under the condition of low SNR. A hyperbolic frequency-modulation synchronization design was used to ensure synchronization acquisition performance. The results of the hardware-in-the-loop simulation demonstrated the effectiveness of the system.

Keywords

• mobile underwater acoustic communication
• doppler compensation
• signal-noise-ratio
• hyperbolic frequency modulation