網際GPS自動化算服務之研究

Abstract

傳統的GPS (Global Position System) 相對定位測量，使用者至少必須使用兩組的GPS接收儀以及GPS觀測資料後續的處理軟體。這對於GPS的使用者來說不但增加軟硬體的投資，而且在外業上也必須至少同時操作兩台的接收儀。同時，資料的處理對於GPS方面的新手來說也相當的困難，諸如GPS原始資料的下載 、軟體的使用等等。 網際GPS自動化算服務的建構解決了這一些問題。在外業上，GPS使用者只需要操作一台接收儀不需要基站就可以完成所有的定位的工作。在內業方面，GPS使用者不再需要購買以及維護任何的資料處理軟體，甚至不必了解軟體的操作。在資料處理完成之後，資料的成果是以電子郵件的方式通知使用者。 本研究描述使用者如何透過網路使用這種網際GPS自動化算服務系統。以國立交通大學所設置的NCTU固定站以及國立成功大學所設置的DONS固定站作為測試的測站，2001年三月的觀測資料作為測試數據。首先利用國際IGS衛星追蹤站武漢(WUHN)以及馬尼拉天文台(PIMO)解算NCTU以及DONS固定站2001/3/1至2001/3/7七天的觀測資料，以這七天逐天解算成果的平均值當為真值，比較網際GPS自動化算服務系統在觀測時段24小時、6小時、4小時以及2小時解算的成果。所選用的精度指標包括：絕對值平均誤差、絕對值最大誤差以及絕對質最小誤差三種。本研究中在觀測時段24小時的情況下，每個GPS自動化算服務系統解算的成果的平面誤差皆在公分級以下，在高程方面不同的GPS化算服務系統則有不同的結果，有的成果在2~3公分，有的成果在10~20公分。在比較基線長的部分，誤差在170286.0442m 29.63mm。

In the conventional relative GPS surveying, user have to use a minimum of two sets of GPS receiver, as well as the associated processing software package. This is not only a increasing for hardware and software, users must have to operate two GPS receiver outside at one time. In addition, in many instances the data processing step may be more difficult for users with minimum experience in GPS technology, involving as it does the downloading of data files into a PC, the operation of software, etc. Those problems can be solved by the Internet GPS Service. In this way the users can finish all works outside with only one GPS receiver and will no longer need any basestation and to buy and maintain any data processing software, or even understand the operation of such software. The users will be notified of their results by e-mail after the data processing step has been completed. This paper describes how users using the Internet GPS service via Internet. Testing two fixed station NCTU and DONS established by National Chiao Tung University and National Cheng Kung University, time of observation file is from 2001/3/1 to 2001/3/31. At first, the IGS station WUHN and PIMO are used to be the reference station and solve the NCTU and DONS during days from 2001/3/1 to2001/3/7. Computation of the mean of those seven days is to be the true value and compare with the result which is solved by Internet GPS Service with observation interval 24, 6, 4 and 2 hours. The result is evaluated using mean absolute error, maximum absolute error and minimum absolute error. In this paper, in the situation of observation interval of 24 hours, the error on 2D of all Internet GPS Service is in the cm level, but there are different results in height, some are at the 2~3 cm level, some are at the 10~20 cm level. In the baseline, the error is 170286.0442m 29.63mm