Underwater Robot Communication System Design And Implementation

As human is more and more in-depth development of the marine world,underwater robots as the main tool for marine development, has become the focus ofnational research. This article focuses on the communication between underwaterrobots.Underwater robots are divided into two kinds, cable robots and no-cable robots.Cable robots have greatly limited the scope of use, and they can’t do a lot of complexwork in shallow water environment. No-cable robots control flexible and able to adaptto the complex environment of the shallow probing inspection tasks, so no-cable robotsare widely applied and has become the core of national research.This paper is concentrate on communication between underwater robots. In fact,the underwater robot communication research is research of communication in shallowwater channel environment. Shallow water channel is a complex multi-path channel.Channel parameters will change with the change of time, space and frequency. Shallowchannel has become one of the most complex communication channels. Theattenuation of electromagnetic waves in the water is very high, so the transmissionpropagation distance is very segment and electromagnetic information can not betransformed in the shallow water environment. The low-frequency acoustic signals canbe transmitted in water tens of kilometers. So the acoustic signals can be realizedunderwater communication. Underwater acoustic communication system is the corecontent of underwater robot communication system.The paper selects the fourth generation mobile communication technology OFDMas the basic theory of the communication system of underwater robot. OFDMtechnology has excellent resistance to multipath interference. It is used to realizeunderwater robot acoustic communication.OFDM technology is proposed for quadrature modulation scheme of the presentsystem to achieve orthogonal frequency division multiplexed. Various parameters ofthe communication system is determined according to the channel characteristics and the communication requirements of the robot. MATLAB tool is use to establish acommunication system simulation model for analysis. Finally verify that the system isable to complete the underwater acoustic communication function.One of the main works is the implementation of the communication systemtransmitter. This article is complete transmitter signal processing portion by FPGA,Including functional module: USB control, framing, channel coding, interleaving,symbol mapping, interpolation, IFFT, cyclic prefix is inserted, DAC control. Foranalog Signal Processing, this article describes the digital-to-analog conversion moduleand filter circuit design. In this paper, experiments verify system performance.Experiments show that the bit error rate of is less than0.02%. This proves that thesystem can be good to overcome multipath interference, to achieve the effect of goodcommunication.