Method and device for measuring dissolved oxygen based on dual-channel lock-in amplifying technique

Abstract

The invention belongs to the technical field of ocean observation and discloses a device and a method for measuring dissolved oxygen based on a dual-channel lock-in amplifying technique. The device comprises an oxygen sensitive membrane, an optical detection module, a signal modulation and demodulation module, a signal processing module, a system control module, a communication module and a power management module. Through the technical scheme, the device and the method are capable of measuring the content of the dissolved oxygen in the water in real time, are free of consumption of samples and free of pollution, is stable and efficient, and is also capable of achieving remote on-line in-situ monitoring.

Description

technical field [0001] The patent of the present invention relates to the technical field of marine monitoring, in particular to a dissolved oxygen measuring device and method based on dual-channel lock-in amplification technology. Background technique [0002] Oxygen is closely related to people's production and life. The determination of dissolved oxygen has important applications in aquaculture, papermaking, metallurgy, chemical oil refining, sewage treatment, and medical biology. Traditional dissolved oxygen measurement techniques mainly include titration iodometric method, electrochemical method and analog lock-in amplification method. Since the iodometric method consumes a large amount of samples, remote monitoring cannot be realized, and the sensor made by the electrochemical method has inherent defects such as easy contamination, frequent cleaning, instability and failure. Although the analog lock-in amplification technology can detect the weak dissolved oxygen sign...

AI Technical Summary

Problems solved by technology

Since the iodometric method consumes a large amount of samples, remote monitoring cannot be realized, and the sensor made by the electrochemical method has inherent defects such as easy contamination, frequent cleaning, instability and failure.

Although the analog lock-in amplification technology can detect the weak dissolved oxygen signal submerged in the strong noise background, it has strict requirements on the phase of the reference signal.

Because the prerequisite for the output DC signal to be proportional to the amplitude of the measured signal is to ensure that the frequency of the input signal and the reference signal are the same, and the phase difference is 0, because the initial phase difference between the useful signal and the reference signal is different. Can have a large impact on the output of the multiplier and low-pass filter

The DC output signal of the lock-in amplifier can truly reflect the change of the actual signal when the initial phase difference is 0, but the detection effect in other cases is not ideal, and the measured dissolved oxygen parameters are quite different from the actual ones.

This requires adding a phase shift circuit between the reference signal and the measured signal to ensure that the phase difference between the two is 0, but there are many difficulties in real-time and accurate adjustment of the phase difference to 0.

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