📄 page_169.html
字号:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <title>page_169</title> <link rel="stylesheet" href="reset.css" type="text/css" media="all"> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> </head> <body> <table summary="top nav" border="0" width="100%"> <tr> <td align="left" width="30%" style="background: #EEF3E2"><a style="color: blue; font-size: 120%; font-weight: bold; text-decoration: none; font-family: verdana;" href="page_168.html">< previous page</a></td> <td id="ebook_previous" align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_169</strong></td> <td align="right" width="30%" style="background: #EEF3E2"><a style="color: blue; font-size: 120%; font-weight: bold; text-decoration: none; font-family: verdana;" href="page_170.html">next page ></a></td> </tr> <tr> <td id="ebook_page" align="left" colspan="3" style="background: #ffffff; padding: 20px;"> <table border="0" width="100%" cellpadding="0"><tr><td align="center"> <table border="0" cellpadding="2" cellspacing="0" width="100%"><tr><td align="left"></td> <td align="right"></td> </tr></table></td></tr><tr><td align="left"><p></p><table border="0" cellspacing="0" cellpadding="0" width="100%"><tr><td align="right"><font face="Times New Roman, Times, Serif" size="2" color="#FF0000">Page 169</font></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3">wavelength and works for any of the four phase variables previously discussed. Alternative approaches to implementing the integer search are presented, for example, in Refs. 61 and 89.</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3">Consider a set of <i>n </i>> 4 differentially corrected phase measurements of wavelength </font><font face="Symbol" size="3">l</font><font face="Times New Roman, Times, Serif" size="3">:</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3"><img src="16336b434a5818429b2cc7f7b12bf546.gif" border="0" alt="0169-01.GIF" width="360" height="47" /></font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3">where the measurements are partitioned into primary and secondary measurement sets. The ambiguity resolution algorithm proceeds by hypothesizing a set of integers for the primary set of measurements and using the secondary set of measurements as a test of each hypothesis. The primary set of measurements must have at least four satellites, and these four should be selected to have a reasonable GDOP.</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3">Assume also that at the initial algorithm step, x = 0, var(x) = <i>P</i> = </font><font face="Symbol" size="3"><i>s</i></font><i><font face="Times New Roman, Times, Serif" size="1"><sub>x</sub></font><font face="Times New Roman, Times, Serif" size="3">I</font></i><font face="Times New Roman, Times, Serif" size="3">, var(</font><font face="Symbol" size="3"><i>b</i></font><font face="Times New Roman, Times, Serif" size="3">) = <i>R</i> = </font><font face="Symbol" size="3"><i>s</i></font><font face="Symbol" size="1"><sub>b</sub></font><font face="Times New Roman, Times, Serif" size="3"><i>I</i>, and </font><font face="Symbol" size="3"><i>s</i></font><i><font face="Times New Roman, Times, Serif" size="1"><sub>x</sub></font></i><font face="Times New Roman, Times, Serif" size="1"><sub></sub></font><font face="Times New Roman, Times, Serif" size="3">>> </font><font face="Symbol" size="3"><i>s</i></font><font face="Symbol" size="1"><sub>b</sub></font><font face="Times New Roman, Times, Serif" size="3">. These assumptions, although realistic, are not necessary for the algorithm to work, but allow a theoretical basis for the algorithm derivation. The phase measurements will be processed by recursive least squares, as described in Sec. 4.1.2.</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3">The search algorithm will be implemented as a nested triple ''for" loop. Before the loop is initialized, the following variables should be defined to minimize calculations within the loop:</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3"><img src="63234c8a4e0ddd7da70c6a3144246e92.gif" border="0" alt="0169-02.GIF" width="299" height="25" /></font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3"><img src="829a848d87457b9ee5d64fb4e081188d.gif" border="0" alt="0169-03.GIF" width="294" height="22" /></font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3"><img src="2cd2de4388fa2afac7630cb1998ae891.gif" border="0" alt="0169-04.GIF" width="292" height="22" /></font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3">The meaning of each variable is defined below.</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3">The algorithm proceeds as follows:</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3">1. Hypothesize a set of integers N</font><font face="Times New Roman, Times, Serif" size="1"><sub><i>p</i></sub></font><font face="Times New Roman, Times, Serif" size="3"> = [0, <i>N</i></font><font face="Times New Roman, Times, Serif" size="1"><sub>2</sub></font><font face="Times New Roman, Times, Serif" size="3">, <i>N</i></font><font face="Times New Roman, Times, Serif" size="1"><sub>3</sub></font><font face="Times New Roman, Times, Serif" size="3">, <i>N</i></font><font face="Times New Roman, Times, Serif" size="1"><sub>4</sub></font><font face="Times New Roman, Times, Serif" size="3">]</font><font face="Times New Roman, Times, Serif" size="2"><sup><i>T</i></sup></font><font face="Times New Roman, Times, Serif" size="3"> for the primary measurements. Each of the three "for" loops counts over a range of one of these three integers (i.e., <i>N</i></font><i><font face="Times New Roman, Times, Serif" size="1"><sub>i</sub></font><font face="Times New Roman, Times, Serif" size="3">, i</font></i><font face="Times New Roman, Times, Serif" size="3"> = 2, 3, 4). If <i>m</i> integer values on each side of a nominal integer are hypothesized, then the entire algorithm will iterate (2<i>m</i> + 1)</font><font face="Times New Roman, Times, Serif" size="2"><sup>3</sup></font><font face="Times New Roman, Times, Serif" size="3"> times. The first integer is artificially set to zero to make the solution unique.</font><font face="Times New Roman, Times, Serif" size="2"><sup>**</sup></font><font face="Times New Roman, Times, Serif" size="3"> Note that without this assumption, all the integers could be increased by <i>i</i> and the clock bias estimate could be increased by <i>i</i> wavelengths without affecting the position solution. The clock bias that results in the following is <i>c</i></font><font face="Symbol" size="3">D</font><font face="Times New Roman, Times, Serif" size="3"><i>t</i></font><i><font face="Times New Roman, Times, Serif" size="1"><sub>r </sub></font></i><font face="Times New Roman, Times, Serif" size="1"><sub></sub></font><font face="Times New Roman, Times, Serif" size="3">- <i>N</i></font><font face="Times New Roman, Times, Serif" size="1"><sub>1</sub></font><font face="Symbol" size="3">l</font><font face="Times New Roman, Times, Serif" size="3">. If it is necessary that the code and the phase clock estimates match, then <i>N</i></font><font face="Times New Roman, Times, Serif" size="1"><sub>1</sub></font><font face="Times New Roman, Times, Serif" size="3"> can be estimated based on the average of their discrepancy.</font><font face="Times New Roman, Times, Serif" size="3" color="#FFFF00"></font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0" width="100%"><tr><td rowspan="5"><img src="f7703d30723feae8ee39d997c6419c20.gif" border="0" width="24" height="1" alt="f7703d30723feae8ee39d997c6419c20.gif" /></td> <td colspan="3" height="12"></td> <td rowspan="5"><img src="f7703d30723feae8ee39d997c6419c20.gif" border="0" width="24" height="1" alt="f7703d30723feae8ee39d997c6419c20.gif" /></td></tr><tr><td colspan="3" height="1"><table cellpadding="0" cellspacing="0" border="0"><tr><td></td></tr></table></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="2"><sup>** </sup>Actually, integer <i>N</i></font><font face="Times New Roman, Times, Serif" size="1"><sub>1</sub></font><font face="Times New Roman, Times, Serif" size="2"> is subtracted from all elements of N</font><font face="Times New Roman, Times, Serif" size="1"><sub><i>p</i></sub></font><font face="Times New Roman, Times, Serif" size="2"> and N</font><font face="Times New Roman, Times, Serif" size="1"><sub><i>s</i></sub></font><font face="Times New Roman, Times, Serif" size="2">, and <i>N</i></font><font face="Times New Roman, Times, Serif" size="1"><sub>1</sub></font><font face="Symbol" size="2">l</font><font face="Times New Roman, Times, Serif" size="2"> is subtracted from the clock bias estimate. This results in the first component of the vector being zero.</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table></td></tr></table><p><font size="0"></font></p>聽 </td> </tr> <tr> <td align="left" width="30%" style="background: #EEF3E2"><a style="color: blue; font-size: 120%; font-weight: bold; text-decoration: none; font-family: verdana;" href="page_168.html">< previous page</a></td> <td id="ebook_next" align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_169</strong></td> <td align="right" width="30%" style="background: #EEF3E2"><a style="color: blue; font-size: 120%; font-weight: bold; text-decoration: none; font-family: verdana;" href="page_170.html">next page ></a></td> </tr> </table> </body> </html>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -