A dynamic data transmission technology for expendable current profilers is proposed in this paper. Two parallel varnished wires are employed as the data transmission medium. By testing the transmission properties of the varnished wires, a baseband transmission system is studied and designed. Modified low-voltage differential signaling is adopted as the physical layer for data transmission. The data transmission protocol is modified and optimized in accordance with the RS 232 protocol, and the

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... nchester code is superimposed. According to the results of indoor and marine tests, the data transmission distance of the designed system, which employs a 0.1 mm diameter varnished wire, extends to 2 km with high efficiency and accuracy for data transmission, exhibiting excellent performance. Moreover, this data transmission technology could be used for other expendable marine-environment parametric measuring instruments such as an expendable bathythermograph and an expendable conductivity temperature depth profiler.