臺灣博碩士論文加值系統

本論文探討在多重路徑環境下，利用陣列接收機所接收之訊號，辨識直視路徑訊號所對應之指向天線方法，以改善訊源誤判問題。
本論文使用模稜函數，估測各多重路徑與直視路徑之相對延遲時間。此外，採用正規化最小均方演算法估測多重路徑通道模型，包含延遲時間與通道增益，以驗證模稜函數所估測之時間延遲。
論文所提方法比對所得之通道估測，與各指向天線與全向監視天線之互相關計算結果，以判斷辨識直視路徑入射方向所對應之指向天線。利用此資訊，可避免來自多重路徑方向之訊源誤判。
論文以擷取之雷達訊號及抽頭延遲線通道模型進行軟體模擬及硬體實驗，以探討演算法之可行性及未來改進方向。

This thesis investigates a method that identifies a directional antenna corresponding to the line of sight signal source based on radar array received signals in a multipath propagation environment. The method can improve false decision of signal direction problem.
This work uses an ambiguity function to estimate the relative time delay between each multipath and the line of sight. Additionally, a normalized least mean square algorithm that identifies the multipath channel model including the time delays and gains are also used to verify the estimation results of the ambiguity function.
The proposed method compares the channel estimation and the cross-correlation results of each directional antenna and an omni-directional surveillance antenna to determine the incident line-of-sight and multipath signals corresponding directional antennas. With such information, false alarms in the directions associated with multipath can be avoided.
Computer simulations and experiments are performed to verify the feasibility of the proposed method, where a set of recorded radar signals are used as sources and a tap-delay-line model is adopted to simulate a multipath channel. Future work of improving the proposed method is also discussed based on the verification.

摘要 I
ABSTRACT II
致謝 III
目錄 IV
圖目錄 VI
表目錄 VIII
第1章 緒論 1
第2章 文獻探討 2
2.1 多重路徑通道模型 2
2.2 模稜函數 4
2.3 正規化最小均方演算法 5
第3章 直視路徑與多重路徑訊號辨識演算法 7
3.1 接收端陣列天線架構 7
3.2 模稜函數演算估測時間延遲方法 8
3.3 正規化最小均方演算法估測通道模型方法 13
第4章 模擬與分析 14
4.1 使用模稜函數估測時間延遲 14
4.2 NLMS演算估測通道模型驗證模稜函數估測時間延遲 17
4.3 BPSK及雷達訊源使用NLMS演算法問題分析 18
第5章 訊號擷取與結果分析 24
5.1 訊號擷取與降頻處理 24
5.2 擷取之訊號使用模稜函數演算 28
5.2.1 25MHz數位中頻轉換之基頻訊號降取樣2倍 28
5.2.2 500MHz數位射頻轉換之基頻訊號降取樣43倍 30
第6章 結論與後續研究方向 32
參考文獻 33

[1]F. Colone, et al., "A Multistage Processing Algorithm for Disturbance Removal and Target Detection in Passive Bistatic Radar," IEEE Trans. Aerospace and Electronic Systems, vol.45, pp. 695-722, 2009.
[2]F. Colone, et al., "Cancellation of Clutter and Multipath in Passive Radar Using a Sequential Approach," in Proc. of the 2006 IEEE Conference on Radar, April, 2006.
[3]T. S. Rappaport, Wireless Communication: Principles and Practice Second Edition, Prentice Hall, 2002.
[4]M. A. Richards, Fundamentals of Radar Signal Processing, McGraw-Hill, pp.159-173, 2006.
[5]C. E. Cook and M. Bernfeld, Radar Signal: An Introduction to Theory and Application, Artech House, 1993.
[6]R. Jacob, et al., "Fast Computation of Wide-band Ambiguity Function and Matched Filtering in Active Sonars," Ocean Electronics, pp. 40-47, 2011.
[7]S. Sen, et al., "Adaptive Design of OFDM Radar Signal With Improved Wideband Ambiguity Function," IEEE Trans. Signal Processing, vol. 58, pp.928-933, Feb., 2010.
[8]B. R. Mahafza, Radar Systems Analysis and Design Using Matlab, Chapman &; Hall/CRC, 2005.
[9]J. M. Thomas, et al., "Ambiguity Function Analysis of Digital Radio Mondiale Signals for HF Passive Bistatic Radar," Electronics Letters, vol. 42, no. 25, pp. 1482-1483, June, 2003.
[10]S. Haykin, Adaptive Filter Theory Fourth Edition, Prentice Hall, pp. 231-343, 2008.
[11]K. Elangov, "Comparative Study on the Channel Estimation for OFDM System Using LMS, NLMS and RLS Algorithms," Informatics and Medical Engineering(PRIME), pp. 359-363, March, 2012.
[12]Lyrtech, VHS-ADC/DAC User’s Guide, March, 2009.
[13]Lyrtech, Twin Tunable RF Transceiver User Guide, 2009.
[14]National Instruments, NI PXIe-5185/5186 Specifications, March, 2011.