Light noise filtering-out apparatus for optical water quality measurement system

Abstract

The invention relates to a light noise filtering-out apparatus for an optical water quality measurement system. The light noise filtering-out apparatus comprises: a signal modulation unit for modulating the light intensity of a light signal emitted by a light emitting unit; a reference signal conditioning unit for carrying out shaping and phase shift on the modulated signal copy obtained from thesignal modulation unit to provide a phase-consistent reference signal; a coherent detection unit for receiving the reference signal transmitted by the reference signal conditioning unit and a detection light signal transmitted by a light receiving unit, and filtering out the stationary light noise in the detection light signal; an autocorrelation unit for receiving the signal output by the coherent detection unit and carrying out autocorrelation operation according to a signal period; a dynamic observer for receiving the signal output by the autocorrelation unit, filtering out the non-stationary light noise in the signal, and outputting a current state vector; and an effective light intensity output unit for extracting a light intensity variable from the current state vector, and outputting an effective light intensity after filtering out the stationary light noise and the non-stationary light noise. The light noise filtering apparatus of the present invention can effectively filter out stationary and non-stationary environment light noise.

Description

technical field [0001] The invention relates to an optical water quality measuring instrument, in particular to an optical noise filtering device. Background technique [0002] Optical measuring instruments, especially optical measuring instruments based on scattering method, fluorescence method, transmission method, etc., are widely used in the process of outdoor operation, such as surface water body SS (suspended particulate matter concentration) and COD (chemical total oxygen demand) index measuring instruments In the face of ambient light interference, such as ultraviolet and infrared rays in sunlight, they will also enter the photodetector through reflection and scattering of the water sample to be measured. The sun is the main source of ambient light interference. In general, sunlight is stronger than artificial light. It is a non-modulated light source and has a wide spectral bandwidth. The artificial light source used for lighting is usually a kind of modulated ligh...

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Problems solved by technology

[0004] In view of the above-mentioned defects in the prior art, the purpose of the present invention is to provide an optical noise filtering device suitable for optical water quality measurement systems, so that it can effectively solve the problems encountered in the use of optical water quality measurement instruments. Optical noise interference problem, while controlling manufacturing costs, improving its ease of deployment, maintainability and real-time measurement

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