Design Of An External Field Simulator For A Certain Type Of Impulsive Altimeter

Due to the requirement of fast in-situ testing for radio altimeter,it is necessary to have functional devices with analog and simulated echo signal,and altimeter simulator arises at the historic moment.The main content of this paper is to design a simulation of impulse radio altimeter echo altimeter field simulator,to achieve a high degree of simulation and sensitivity of radio altimeter simulation,so as to realize the function of the performance test of radio altimeter,meet the requirements of the aircraft altimeter.The main contents are arranged as follows: first,the working principle of radio altimeter and altimeter detection is briefly introduced,and the design scheme of the altimeter external field simulator is put forward,and the basic architecture design and implementation method of altimeter field simulator system are discussed in detail.The system is mainly composed of PC104 microprocessor unit,radio frequency link unit,power unit,delay control board unit and interface unit.The functions of each component are described in detail.The radio frequency link unit and the delay control unit are the key modules of the system design.The RF link unit includes the 0m delay,the 1000 m delay and the variable delay unit.Variable delay part use Altera FPGA based on large scale integrated circuit board delay control and time delay control to achieve control of frequency conversion,frequency,channel selection,and PC104 in the control of the microprocessor unit,the radio altimeter data and the dynamic simulation function of fixed height.The test chamber is verified,which ensures the rationality and correctness of the design.Finally,it is applied to outfield test and outfield protection for a certain type of pulse radio altimeter.In this paper,the radio altimeter external field simulator of the pulse system is studied.The main achievements are as follows:1.the antenna is coupled with the antenna signal,and it can be connected with the aircraft without electrical connection at work,and the function simulation of the radio altimeter is realized.2.the working condition of the altimeter is simulated with fixed height and dynamic simulation,and all the basic working conditions of the radio altimeter are simulated.