Design And Implementation Of Reconstructed Radio Altimeter

The radio altimeter is an important navigation equipment for aircraft,missile and other aircraft,it can accurately measure the real altitude of the aircraft relative to the ground or sea in various climatic conditions,in order to ensure the aircraft to perform the the related tasks.Currently most of the radio altimeter uses analog discrete devices,the main functions are realized by hardware circuits,for more and more complex electronic systems on the aircraft,the radio altimeter is difficult to integrate and the resources can not be shared.In recent years,with the wide application of spread spectrum technology and software radio technology,the new digital radio altimeter based on pseudo code ranging system,has adopted the FPGA+DSP architecture mode and realized the design of board type,which has the advantages of small size,light weight,low power consumption,wide range of height measurement,high precision and strong anti-interference ability,etc,and the reconfiguration design strengthens the integration of the core software,realizes the resource sharing,the system can configure the running channel of each function flexibly,and facilitates the management,upgrading and maintenance of the software on the machine.Firstly,the thesis briefly describes the basic principle of pseudo-code ranging and the overall design of a radio altimeter based on a pseudo-code ranging system,it discusses the hardware and software design of a reconfigurable radio altimeter in detail and describes the various components(transmitting antenna.,receiving antenna,ALT receiving / excitation module,functional module)design ideas,hardware implementation block diagram,the main device selection;ALT module software and ALT function software design ideas and design process.Then the main technical problems in the design are analyzed and researched,and the specific implementation methods are given,including:(1)In order to realize the resource sharing of the system,a reconfiguration design method is adopted;(2)To adapt to 500m/ The tracking rate of s uses the high-speed tracking technology of multi-channel parallel processing,and tests its performance in the laboratory;(3)In order to solve the formation flight of the aircraft,the random code-breaking technique is proposed and the implementation process is described;4)For the change of the strength of the external signal,the implementation process of the AGC control design and the selection principle of the IF control word in the project implementation are described.Finally,the application of the configuration radio altimeter is briefly described,the laboratory test and the field test data are analyzed,it is verified that the reconstructed radio altimeter based on the pseudo-code ranging system works stably and reliably,and meets the overall development requirement.