Research And Implementation Of Remote Metering Radar For Micro Deformation

The rapid development of economy and science technology has led to the constantbreakthroughs in construction industry, with various ultrahigh pressure cross-rivertowers, large-scale bridges, skyscrapers and large-scale dam successively emerging invarious countries all around the world. However, these large-scale buildings or theircomponents may be deformed while being used, especially in disastrous weather, thedeformations will be aggravated, and even exceeding the safe range of deformation,which undoubtedly resulted in catastrophic consequence. Therefore, it will guaranteethe safe utilization of these buildings by the supervisions of their deformations. Thispaper aims to realize the detection on the micro-deformations of large-scale buildings,and discuss the solutions of the issues encountered in the realization process. And themain research contents of this paper include the theoretical research and analysis of thedeformation measuring system of large-scale buildings, the hardware realization ofremote measuring radar system for micro-deformation, and a series of problemsencountered in the system realization processThe research achievements of this paper can be summed up as follows:First, theoretically analyze the remote measuring radar system formicro-deformation, propose the remote measuring radar system for micro-deformationbased on the microwave ratio and the spread spectrum code division multiple accesstechnology, and provide the schematic diagram of system realization. The simulationsresults show that the remote measuring method of micro-deformation specified hereincan efficiently distinguish the signals of various beacon transmitters from compositesignals, and isolate the signal waves of each beacon transmitter on the base that relativephases keep unchanging. By comparing the relative phases of the isolated signal waves,it can accurately calculate the range difference between the under-measured beacontransmitter or the reference transmitter and the receiving antenna.Second, Analyze the key technology to be realized and key issues to be solved inremote measuring system of micro-deformation, which mainly include: selection of PNcode, problem resolution of resources possessed in large amount and multiple accessinterference, etc.Selection of PN code: this paper analyzed the autocorrelations and crosscorrelations of various PN codes according to special requirements of remote measuring radar system for micro-deformation, and determined the optimal PN code for thissystem, put forward the method of distinguishing beacon transmitters in differentchannels through using the differences of PN codes’ relative phases according to thespecialties of distance measurement in this program. According to the method, onlytwo-channel PN codes with good orthogonality are needed to distinguish multi-channelbeacon transmitters.The issue of possessing a large amount of resources in hardware circuit design: thispaper designed and realized the improved digital down conversion (DDC) and theimproved digital Costas loop circuit, adopted the method of replacing Direct DigitalSynthesizer (DDS) module with Logical Control module to realize digital downconversion and phase locked loop, therefore, the purpose of saving the digital signalprocessing resources is achieved. Such method has significant application values inmulti-channel carrier signal extraction and down-conversion, especially in array radarsignal processing. As for the issue of possessing a large amount of resource in directdesign of narrow-band filter encountered in the processes of pseudo code capturing andtracking, the purpose of saving a large sum of FPGA resources is achieved throughutilizing the correlation in filter coefficients and establishing equivalent narrow-bandfilter by the method of interpolation filtering. According to the specific situation of theremote measuring radar system, the improved spread scheme is proposed. Using theapproximate equivalent method, we resort to the one-line capture and track circuit torealize the spread function of the multichannel signals, which will also bring about thelow energy consuming.Multiple access interference elimination: this paper analyzed various eliminatingmethods of code division multiple access, concluded that the paiallel interference offsettechnology is the optimal method for eliminating multiple access interferences inremote measuring radar system for micro-deformation. And simulation of the realizationof such method was created with good effect.Third, a whole set of transmitting and receiving system of remote measuring radarfor micro-deformation was designed, and a deformation survey of buildings underpractical conditions was conducted with good effect. Such system includes: transmittingdesign circuit, RF transmitter, transmitting antenna, receiving antenna, RF signal downconversion, intermediate-frequency signal digitization, digital down conversion module,dispreading module, signal carrier isolation module, multi-channel carrier phasedifference calculation and the formation and display module of deformation curve. Such system contains all contents realizing the deformation measurement of large-scalebuilding and provides a significant platform for further study on the micro-deformationmeasuring radar of large-scale buildings.