FMCW SIGNAL PROCESSING OF GROUND PENETRATING RADAR AND 3N-GPR DISPLAY

• Main Author: YENAS - NIM : 13214022 , NURUL
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/29850
• Institution: Institut Teknologi Bandung

<p align="justify">The underground structural map is one of the most important aspects of infrastructure development. In Indonesia, the information of underground structural map is inadequate. As a result, the construction of new buildings can damage existing infrastructure such as power lines, plumbing, data communication cables, etc. To prevent this, it is necessary to survey the land prior to infrastructure development. Ground Penetrating Radar (GPR) is an instrument that can be used to perform such underground survey. In this final project, we develope GPR instrument, refered to as 3N-GPR which has compact, low cost, portable, and user friendly features. 3N-GPR consists of 5 main parts namely GPR frame, antenna, baseband module, signal processing module, and display. Specifically, the scope discussed in this final project document includes both signal processing and display modules. 3N-GPR is designed to detect underground pipeline in the depth range of 0-2 meters. It is required that the depth information and the position of underground pipes are displayed on a tablet. To obtain this information, it is necessary to process the echo/reflected signal using raspberry pi 3 as signal processor module. The main parts of the software implemented on raspberry pi 3 consist of: submodule plotting, Fast Fourier Transform (FFT) computation, windowing process, and pipe depth information. The plotting submodule is used to represent the beat waveform, whereas FFT computation submodule is utilities to obtain the beat frequency in determining the depth of underground pipe. The windowing process acts to eliminate noise and to convert the values resulting form FFT computing into logarithmic scale to enhance the difference between the ground with the object to be detected. The last process is the unit conversion to obtain the depth information and the position of underground pipes in meters. All informations and processes will be displayed on the tablet. In addition, there is a Graphical User Interface (GUI) which consists of several menus and sub menus to facilitate the user in operating the 3N-GPR display. After being integrated with all GPR module, the function of signal processing module was tested using input signals received by the receiver antenna. Here, we have obtained the beat waveform signal and the FFT spectrum whose frequency varies when the distance between the transmitter and receiver antennas facing each other is changed. The windowing processes of this FFT signal have also been successfully perform using Hamming Window function. To evaluate the information processing on the position of the underground pipes, an emulation test is performed using input signals from a function generator. In this test, the frequency of the function generator was varied in a value range corresponding to a depth of 0 to 2 meters. The GUI developed for the instrument has been able to provide menus, submenus, and widgets that make it easier for user to operate. <p align="justify"> <br />