Study And Application On Ranging Principle Of LFMCW Radar Material Level Measurement Instrument

Ranging is the most essential function of radar. High-precision ranging, especially the short range, is an important application field of civil radar. The radar using LFMCW (Linear Frequency Modulation Continuous Wave) technology is a comprehensive system which acquires information of distance and velocity through frequency modulation. Because of the advantages of no range blind area, high range resolution, low signal power and simple structure, LFMCW radar has attracted more and more attention recently. The theories, key technologies and applications develop rapidly.Firstly, this paper introduces merits and demerits of LFMCW radar technologies and its applications in all fields, analyzes the make up of radar system. Through the classical radar ranging equation, the effect and application of radar transmitting wave modulated by different types of modulation signals are analyzed. The relative ranging resolution arithmetic of LFMCW radar are studied, including the precision influence factors, significance and purpose of studying transmitting wave linearity and ambiguity function to ranging resolution, and ways of improving frequency resolving power.This paper mainly studies the hardware components working principles of radar transmitting source in the instrument, including voltage controlled oscillator, isolator, circulator, mixer, aerials. The hardware parameters are determined. In electrical circuit unit, those are studied including signal generator circuit, temperature compensation circuit and filter network. The working principles and flowchart of signal processing module are illustrated as well.Finally, the adjustment experiment of radar material level measurement instrument system is devised. Through the experiment of microwave beat signals stability and distance measurement resolution in simulation working field, the stability and resolution of the specimen instrument are tested.The main research work and results can be summarized as follows:1. Ranging principle and arithmetic of improving measurement resolution of LFMCW radar are studied.2. Accomplishing system design of the material level measurement instrument, and the selection and computation of key parameter.3. Adjusting the hardware components of the radar transmitting and receiving units with the relative instruments, providing the working parameters in practice.4. Accomplishing and debugging the hardware electrical circuit board.5. Designing the shape and structure of the instrument, debugging the hardware system, validating the measurement effect of the specimen instrument in the working field.