The Design And Implementation Of Acoustic Communication System Based On Offshore CPT

China is a big maritime country since ancient times, and rich in marine resources which have great potential for exploitation. In recent years a growing number of marine engineering facilities is carrying out with the proposition and implementation of national maritime strategy. All marine construction are indispensable to marine geological exploration. And static cone penetration test(CPT) with its unique investigation advantage is playing an increasingly important role in marine geological engineering surveys. The current data communication in CPT equipments are still using cable. But the cable conntecting with the probe may cause some problems: the probe assembly is difficult and time-consuming, cable likely to break in harsh marine environments resulting in data loss and damage to equipment, the cable limits the movement of the probe in downhole subsea CPT equipments and so on.For the existing cable data communication in CPT equipments has some problems, we designed and have realized an acoustic communication system based on offshore CPT. After researching and analysing the wireless communication using in CPT equipments from world wide region.This system takes the probes as the communication media, uses acoustic waves as its data carrier, and is compatible with original interface. So it can be a direct replacement for cable to achieve wireless data communication in CPT equipments. The emphases of this paper are as the follows: Firstly, via doing acoustic wave propagation theory research on probe string and marking simulation experiments, we analyzed the acoustic transmission characteristics of the CPT probe and provide a theoretical basis for the acoustic communication system design. Secondly, by combining some of the existing research results and the experimental data, we demonstrated several key technical solutions of the system. Then longitudinal wave transducers, pulse drive mode, 4DPSK modulation and BCH encoding were determined to use. Thirdly, we specifically studied and introduced hardware and software design of the system. Hardware includes SCM system, acoustic launch circuit, power supply for transmitting and Receiving terminal, signal conditioning circuit. Software includes data caching, data encoding packing, 4DPSK modulation, AGC algorithm, 4DPSK demodulation, data decoding and unpacking. Finally, we tested the function and performance of the system. Experiment results show that the design of hardware and software is reliable and stable. Wireless data communication in CPT equipments could be roughly implemented.