The Research On The Detection System Of Weak Signal Of The Ocean Current Sensor

The ocean flow, which plays an important role in global climate change, coastal erosion and marine life, is one of the important parameters of the marine environment of hydro meteorological. The measure of the ocean flow has always been the focus of marine science and technology workers, and the development of high-performance ocean current sensor is the main direction of development of the current measuring technology.We design a detecting system for the ocean current sensor to measure the weak upwelling signal in this paper. The signal of upwelling is so much weak that it belongs to a weak signal range. In order to overcome it, firstly we summed up the theory of weak signal detection and drew the conclusion that the key to detecting weak signals is to reduce noise and to improve the signal-to-noise ratio. Then we put forward a method of reducing device noise by reducing the number of component, and using a high-precision sigma-delta AD converter with built-in differential amplifier to reduce quantization noise and eliminate temperature drift for the purpose of improving the signal-to-noise ratio of the system. Ultimately, in consideration of the special ocean environment, we design the hardware and software according to the demand of self-contained system, use the ratio metric connection to eliminate the influence on system accuracy caused by the power performance, take advantage of digital filtering to improve the accuracy of the data and write program which uses storage mode in unit to replace page storage mode of AT45DB041memory chip, and analyze the power consumption of the system as well as the storage time. Putting low-power, low-noise, high-precision, high integration first, we design a detecting system which has low-power and battery-powered, based on HX711digital-to-analog conversion circuit. We finish the protracting of the whole principle chart and the facture of the PCB board according to the requirements of electromagnetic compatibility, measure the accuracy of the system through experiment, analyse the performance of the system and verify the feasibility of detecting system on the measure of weak signal.For the sake of the convenience of analysis and data saving, we design a Labview display interface, from whose two-dimensional map we can visually observe the data’s change trend. And the data which is saved automatically in Excel form can facilitate the following data processing. It also generates executable and installable file of display interface in order to enhance the portability of the display interface.The research work based on this project provides important supports for the ocean current sensor in practical application.