利用中壢特高頻雷達新干涉天線陣列觀測中氣層之風場; Using Chung-Li VHF radar to observing the wind field of the Taiwan of mesosphere

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题名:	利用中壢特高頻雷達新干涉天線陣列觀測中氣層之風場;Using Chung-Li VHF radar to observing the wind field of the Taiwan of mesosphere
作者:	鍾明哲;Jhong,Ming-Jhe
贡献者:	太空科學研究所
关键词:	干涉定位;流星尾;風場;interferometric;meteor;wind field
日期:	2013-07-19
上传时间:	2013-08-22 11:41:26 (UTC+8)
出版者:	國立中央大學
摘要:	民國101年，中壢52MHz特高頻雷達站增設了一套干涉天線陣列，由5座八木天線排列成非等間距之十字型，提供干涉定位所需5路接收信號；本研究主要目的是在建立此干涉天線陣列之定位方法；干涉定位時必須利用不同天線間接收目標時，因傳播路徑差而產生之相位差值，推估出目標物的空間位置；由於天線間距均超過半波長，自然會存在空間位置的混淆現象，且接收通道內部之系統相位差，亦會影響定位正確性，本文發展干涉定位技術時，首先必須獲得經由系統正確的相位誤差量，提供各通道接收信號作為補償之依據，接著解算通道間信號相位差，並經由多組求解方式，設法解決空間位置的混淆現象，歸納出目標位置的唯一解。接收通道的系統相位差可以利用中壢地區上空電離層散塊E層(Es)因沿磁場分布(Field Aligned)及其回波信號必須以接近垂直波束角度的指向靈敏性(Aspect sensitivity)特徵，其回波空間位置可以利用IGRF模型得出預測回波分布區；實際散塊E層回波信號經干涉定位後，所得到的空間位置分布，與理論分析所得預測回波位置比較後，即可得出系統相位偏差量。本文成功建立了相位差獲得方法，並用於干涉定位技術，因此可針對空間隨機分布之流星尾信號進行正確定位，得到其高度及方位資料，因流星尾會隨時間擴散並受中氣層風場影響而飄移，依據移動窗區法(Sliding Window)挑選出流星尾資料，並利用最小平方法(Least-squares Method)，由回波都卜勒(Doppler)信號可以估計出中氣層水平背景風場。推算出水平東西向及南北向不同高度之風場分布，經過與HWM和TIDI(TIMED Doppler Interferometer)觀測所獲得風場比較，，其變化趨勢具有一致性，且全日潮(Diurnal Tide)特徵是相當明顯的。 The new interferometry antenna array composed with the five YAGIs is built at Chungli 52MHz VHF radar station in 2012. The antenna array is arranged in the form of an asymmetric cross providing that 5 channels interference received signal. The purpose of this study is to create interferometric positioning formula. Interference positioning requires individual path differences between the receiving antennas and targets. We can estimate the spatial position of the target through phase differences due to propagation path difference. Because all the antenna distances are longer than half wavelength, that leads to phase aliasing. The system phases of receiving channels also affect the positioning accuracy. Interferometer positioning technology developed in this paper, first, needs the correct phase error value of the system. Second, solving channel phase difference between the signals and multi-solving the spatial location aliasing give the unique solution of the target location. The phase differences of receiving channel can be found by collecting the echo signals of sporadic E layer in the ionosphere. The forecast echo distribution of IGRF model provides a theoretical position. We can obtain the differences through the overall comparison between observation and model run. This paper successfully established a method for obtaining the phase difference and interferometric positioning technology. Thus, spatial random distribution of meteor signals is correctly positioned in height and location information. Meteor trail diffuse with the mesosphereupper wind to drift. Using Sliding Window method to choose the meteor data and use them for the estimation which is by means of the least squares method of the background mesosphereupper wind field. After surveying the HWM and TIDI (TIMED Doppler Interferometer) wind field observed, they are consist with my results and the Diurnal Tide features are quite obvious.
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