System for measuring solution concentration by using perturbation method

Abstract

The invention relates to the technical field of solution parameter measurement and relates to a system for measuring a solution concentration by using a perturbation method. The system comprises a microwave resonant cavity sensor, a wave detector, a voltage-controlled oscillator, a frequency tracking module, a frequency measuring module and a main control processing module, wherein frequency modulated signals generated by the voltage-controlled oscillator under the control of the main control processing module are divided into two ways; one way is mixed with local oscillator signals so as to generate difference frequency signals; the other way is led into a waveguide and is transmitted and coupled by the waveguide to be coupled into a resonant cavity; reflecting signal inside the resonant cavity enters the wave detector through a circulator; modulating signals output from the wave detector are transmitted into the frequency tracking module; the frequency tracking module comprises an amplitude discriminating module and a phase discriminating module; the main control processing module is used for controlling the carrier frequency of the voltage-controlled oscillator; the output of the frequency measuring module is accessed to the main control processing module; and the main control processing module obtains the corresponding relationship between a frequency offset and a solution concentration. The system can realize accurate and real-time measurement to the solution concentration.

Description

technical field [0001] The invention relates to a control system for measuring solution concentration based on a perturbation method, which can accurately measure and control the solution concentration, and belongs to the technical field of testing. Background technique [0002] In modern industrial and agricultural production, medicine, chemical industry, food and other fields, there is an urgent need for the detection of a wide range of liquid concentration. It is hoped that a new liquid concentration detection system with simple structure, easy control and accurate measurement will appear. [0003] The solution concentration is calculated according to the content of the solute in the solution. In practical applications, the solution concentration also changes due to the change of the solute amount. The measurement methods of solution concentration are divided into direct measurement and indirect measurement. It is the most basic method to directly extract the solution to...

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Problems solved by technology

The indirect measurement method is based on the characteristics of the solution, such as the conductivity of the solution to measure the amount of solute in the solution, but this method can only be applied to electrolyte solutions, which limits its measurement range

[0004] The applicant's previous invention patent application 201210009379.3 provided a microwave resonant cavity sensor and measurement system for measuring solution concentration. The measurement principle of this sensor and measurement system is based on the relationship between the dielectric constant of the solution and the solute content. , can overcome the above-mentioned shortcomings, and has the advantages of simple structure, wide application range, and online measurement. This patent application mainly provides microwave resonant cavity sensors, and the measurement system only provides a basic measurement method. Measurement accuracy needs to be improved

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