Design Of FMCW Level Radar Measurement System

River water level measurement is the most important part of the hydrological work, at present domestic most hydrological station use contact measurement method. This measurement method is easily influenced by underwater sediment and other foreign body, can cause the damage of the phrase or even measurement equipment.Using FMCW radar measuring water level can avoid the above situation. It is an advanced way of non-contact measurement method witch has the advantages of high accuracy and resolution with simple installation. Based on it, this thesis designed the FMCW radar level measurement system.FMCW radar level measurement system calculates the distance between radar and water surface by measuring the IF (intermediate frequency) signal be produced by mixer inside radar, then reach the water level. FMCW radar level measurement system includes several parts:the waveform generator,24GHZ radar sensor, signal sampling and processing module and real-time display module. Waveform generator drives the radar to work by sending the sawtooth wave, the intermediate frequency signal measured by radar sensor is send to the front end signal processing circuit. This circuit can make the intermediate frequency signal suitable for DSP internal ADC sampling and subsequent processing.Then the DSP internal ADC Samples the signal after processing, and DSP do1024-point FFT, get the frequency of IF signal. According to the frequency, the water level can be calculated. After the result coming out, it will be displayed on the viewing screen. This thesis describes the ranging principle of FMCW radar, design of waveform generator and display module, and implementation of AD Samplling and FFT.The measurement system was tested, the experimental datas were recorded and analyzed, the relative error of measurement of this system is within±1%, so the FMCW radar level measurement system is meet the requirements.