應用於雷達系統之 FPGA 實作的六埠接收機

Abstract

本論文係介紹可以將應用於雷達系統之具有自動增益控制的六埠(Six-port)接收機透過無線通訊平台開發板實現的設計。首先探討一般六埠接收機的操作原理及其在雷達系統的應用。接著使用場效可程式邏輯閘陣列(Field Programmable Gate Array, FPGA)實現擁有自動增益控制和I/Q產生器模組的六埠接收機的獨特設計。六埠接收機能夠偵測兩輸入端訊號的相位差。自動增益控制的功能在於改善接收端的動態範圍從-1.8 dBm到-66.8 dBm，增加雷達偵測距離的範圍。I/Q產生器負責提供一組參考用的I/Q訊號。 實驗中探討了接收端和發射端之間的距離對於訊號相位的影響。藉由改變接收端和發射端之間的距離，同時六埠接收機偵測不同距離情況下訊號的相位差。在系統中透過使用公式將量測的相位差推導出偵測的距離，緊接著比較偵測距離和實際的距離得到誤差。偵測相位差和實際相位差的誤差小於5度，在距離138公分到143公分的量測環境情況下，偵測距離的誤差小於1.7釐米。 接著探討入射角和相位差的關係，本論文分別使用連續波訊號、幅移鍵控(Amplitude Shift Keying, ASK)調變訊號、四相相移鍵控(Quadrature Phase Shift Keying, QPSK)調變訊號、二進制頻移鍵控(Binary Frequency Shift Keying, 2FSK)調變訊號和十六進制正交調幅(Hexadecimal Quadrature Amplitude Modulation, 16QAM)調變訊號進行量測。當入射角度為0度，六埠接收機偵測的相位差和實際的相位差的誤差小於3度，偵測的入射角角度和實際的入射角角度彼此之間的誤差小於1度。

In this thesis, the design of a six-port receiver with automatic gain control for radar systems using a wireless communication platform board is reported. At first, the operation principle of the six-port receiver and the application of the receiver in radar system are discussed. Next, a novel design of six-port receiver with automatic gain control and I/Q generator in FPGA are implemented. The six-port receiver detects the phase difference of two input signals. The automatic gain control function is used to improve the receiver’s dynamic range from -1.8 dBm to -66.8 dBm to increase radar detection distance. The I/Q generator is responsible for providing a set of I/Q signals for reference. In experiment, the effect of distance between transmitter and receiver on signal phase is studied. By changing the distance between the antenna of receiver and transmitter, the six-port receiver detects the phase differences. Use the equation with the measured phase differences to derive the distance value detected in the system, and then compared the detected distance value with the actual distance to tell the deviation. The deviation between detected and actual phase difference is less than 5 degrees, and the detection distance deviation are less than 1.7 millimeters from 138 to 143 centimeters measurement. Next, the effect of incident angle on phase difference is studied. In the study, continuous wave signal, ASK modulation signal, QPSK modulation signal, BFSK modulation signal and 16QAM modulation signal are used for the measurement, respectively. When the incident angle is 0 degrees, the deviation between the detected and the actual phase difference is less than 3 degrees, and the deviation between the detected and the actual incident angle is less than 1 degree.