| Long baseline acoustic positioning system is a classic acoustic positioning system. As an important part of this kind of system, the main tasks to the shipborne rangefinder platform are measuring transponder array, launching ask signal and underwater acoustic remote control instruction, receiving underwater acoustic signal from transponder, processing signal and uploading results to PC by network. The software is required to calculate time delay of signal and detect instructions from transponders, then, upload results to PC. The main content of this paper is the design of shipborne rangefinder software, including algorithm implementation,software design process and performance test.The signals of this system include broadband frequency signal and CW signal, using the fast sliding correlation to process the broadband frequency signal and estimate the time delay; using adaptive Notch filter to preprocess CW signal,then,detecting and estimating the time delay by means of VIFD.DSP TMS320C6678 is a high-performance processor with eight cores, which can meet the requirement of real-time processing. The software includes network data transmission module, time delay estimation module and instruction detection module on the basis of SYS/BIOS real-time operating system, loading those four software modules into the first four cores of TMS320C6678. What's more, this paper studied the multi-core loading technology applied to TMS320C6678.Finally, testing the performance of this software by lake experiments, and the facts show that ship rangefinder software can complete the task stably and reliably. |
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