利用微波探測三維地形之研究

Abstract

本研究為發展一套利用電磁波對於現場地形的測量與分析方法。研究中我們考慮到室外氣候與使用的微波的頻段對電磁波的影響，而雷達系統採用主動式微波遙測的架構，設備包含訊號產生器、天線與示波器，為委託大同大學設計與製造。 在現地測量時，使用訊號產生器產生訊號，並藉由發射天線向目標物發射訊號，再由接收天線接收從目標物反射與散射回來的反射波，最後用示波器將此反射波儲存成數位訊號，再對訊號進行分析。 訊號分析採用交互相關方程式(Cross-Correlation Function)。分析的過程由相關係數的理論出發，從發射訊號與接收訊號間的相關係數數列裡，找出各個波峰間的時間延時(Time delay)，再由此時間延時求得現地反射物與發射天線之間的相對距離，並由現場的環境中找出可能的反射點間的距離，來驗證相關係數所求得的結果。從室外實驗的結果，得知本研究所採用的量測方法可以穿透樹叢，並找出現場反射物與發射天線之間的相對距離。

This research is to develop a method of detecting and analyzing the topography by using electromagnetic wave. In this study, we took the influence of the weather and the frequency of the microwave we used into account. Our radar system adopted the framework of active microwave remote sensing. The devices including a pulse generator, three antennas, and an oscilloscope were designed and made by Tatung University. When in field experiments, we used the pulse generator to produce an impulse and emitted signals by the transmitted antenna. Then we received the reflection and scattering signals by the receiving antenna from our targets. We recorded the receiving signals and transformed them into digital data for analysis in the laboratory. The data analysis is on the basis of Cross-Correlation Function. By the theory of the correlation, we could find the time delays between two peaks in the cross-correlation sequence of the data, and then obtain the relative distance from the time delays. We compared the real distances between the possible reflecting targets and our transmitting position with the obtained results to verify our analysis. From the results of the field experiments, we found that the method we developed could penetrate through bushes and workably measure the relative distances between the targets and the antennas.