English  |  正體中文  |  简体中文  |  Items with full text/Total items : 67621/67621 (100%)
Visitors : 23115785      Online Users : 318
RC Version 7.0 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
Scope Tips:
  • please add "double quotation mark" for query phrases to get precise results
  • please goto advance search for comprehansive author search
  • Adv. Search
    HomeLoginUploadHelpAboutAdminister Goto mobile version


    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/27553


    Title: A STUDY OF THE FREQUENCY COHERENCE OF STRATOSPHERIC AND TROPOSPHERIC RADAR ECHOES MADE WITH CHUNG-LI VHF RADAR
    Authors: CHU,YH;FRANKE,SJ
    Contributors: 太空科學研究所
    Keywords: DOMAIN INTERFEROMETRY;LAYERS
    Date: 1991
    Issue Date: 2010-06-29 18:40:48 (UTC+8)
    Publisher: 中央大學
    Abstract: In the past few years the technique of Frequency Domain Interferometry(FDI) has been developed on VHF radar. By using this technique, the characteristics of a very thin atmospheric layer structure, which is embedded in the radar volume and can not be resolved by the conventional VHF radar with only one operational frequency, can be determined through the calculation of the coherence and the phase from two echo signals with slightly different operational frequencies. In this article the results of a frequency domain interferometry experiment carried out on Chung-Li radar are presented. The use of four discrete frequencies and three different frequency separations distinguishes this study from previous investigations. It is shown experimentally that the signal-to-noise power ratio indeed affects significantly the magnitude of the observed coherence. For the first time the dependence of coherence on frequency separation is also investigated. The results show that coherence decreases with frequency spacing with the roll-off rate ranging from -0.2/MHz to -1.2/MHz, depending on the atmospheric structure. After best fitting the theoretical model to the observed coherence taken from a height range with no atmospheric layer existing, the effective range resolution can be found. Employing this information, the thicknesses of two prominent and lasting layers locating at height 7.2 km and 7.8 km are estimated through the least square fitting process, and found to be 114 and 186 meters, respectively.
    Relation: GEOPHYSICAL RESEARCH LETTERS
    Appears in Collections:[太空科學研究所 ] 期刊論文

    Files in This Item:

    File Description SizeFormat
    index.html0KbHTML417View/Open


    All items in NCUIR are protected by copyright, with all rights reserved.

    社群 sharing

    ::: Copyright National Central University. | 國立中央大學圖書館版權所有 | 收藏本站 | 設為首頁 | 最佳瀏覽畫面: 1024*768 | 建站日期:8-24-2009 :::
    DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - Feedback  - 隱私權政策聲明