During underwater signal data transmission process, using Field Programmable Gate Array (FPGA) to calculate Cyclic Redundancy Check (CRC) code with traditional serial calculating method cannot meet the demand of fast computation; however, parallel checking method, which is much faster, has difficulty in practical engineering application because of programming complexity. In order to meet the demand of transmission speed, to eliminate programming difficulty and time waste, a method was proposed to automatically generate parallel CRC code for any length data frames by Matlab. It finished all the mathematical deductions based on matrix method and calculations with the help of Matlab and then generated parallel CRC calculating program which conforms to the Verilog HDL grammar rules. Finally, the CRC calculation program statements generated by Matlab were first simulated in Quartus II 9.0 and then demonstrated by data transmission experiments on a civil towed sonar system. The results prove the validity of the proposed method, its programming and generation can be finished in tens of seconds, and the CRC module can accurately figure out CRC code of every long data frame defined by transmission protocol within requested time.

The paper proposed a precise full-array-synchronization data acquisition clock generation and transmission method to handle the hydrophone's data acquisition synchronization problem in the ocean underwater acoustic detection. By using the independent high-precision clock source and asynchronous differential transmission lines, the long distance synchronous acquisition of the hydro-phone's array was realized, which was characterized with high anti-jamming capability and so on. The detailed model of the full-array-synchronization principle was analyzed and the prototype system was established. Circuits experiment was carried out to verify the feasibility of the entire system. Recovered clock's time delay in the acquisition node was less than 165ns when the low-speed synchronous clock signal was transmitted by the unshielded twisted pair of 18 meters length. The experimental results show that the proposed method has good effect when being applied to transfer the standard clock of data acquisition in the linear array.