差分GPS在中国地磁监测网地理方位角测量中的应用①

金基项目：地震行业科研专项(201208009);地震行业科研专项(201308011)

李秋红1， 辛长江1， 许康生1， 舒雷2， 高慧慧3

(1.甘肃省地震局，甘肃 兰州 730000； 2.内蒙古地震局呼和浩特地震台，内蒙古 呼和浩特 010010；

3.青海省地震局都兰地震台，青海 都兰 816100 )

摘要：中国地磁监测网由地磁台站和流动地磁测点构成，实现对观测网内地磁场的相对记录和绝对观测。它的绝对观测采用世界上最先进的F、D、I测量仪器组合，其中地磁偏角D是地理北和地磁北的夹角。对地磁偏角D的绝对测量要求在地磁台站投入正常观测前必须完成观测墩和观测标志的地理方位角测量，流动地磁测点在每次地磁偏角D观测前后至少进行地理方位角测量各一次。据地磁监测网《观测规范》要求，地磁偏角D的观测精度必须≤6″，所以中国地磁监测网采用天文和差分GPS地理方位角两种测量方法，且两种方法观测精度相当，均≤6″。与天文测量相比，差分GPS观测不受天气等自然因素的限制，操作简单，观测快捷，数据处理计算机程序化。随着GPS技术的普及，中国地磁监测网差分GPS地理方位角测量方法已基本取代了天文方法。本文主要介绍差分GPS在中国地磁监测网地理方位角测量中的应用。

关键词：中国地磁监测网； 地磁场； 差分GPS； 地理方位角

收稿日期：①2014-10-04

作者简介：李秋红(1965-)，女，工程师，主要从事地震监测工作。E-mail: lzhimo@sina.com。

中图分类号:P318.6文献标志码：A

DOI:10.3969/j.issn.1000-0844.2015.03.0862

ApplicationofDifferentialGPStotheGeographicAzimuth

MeasurementinChinaGeomagneticFieldMonitoringNetwork

LIQiu-hong1, XIN Chang-jiang1, XU Kang-sheng1, SHU Lei2, GAO Hui-hui3

(1.Earthquake Administration of Gansu Province, Lanzhou 730000,Gansu，China;

2.Hohhot Seismic Station, Earthquake Administration of lnner Mongolia Autonomous Region, Hohhot 010010, Inner Mongolia，China;

3.Dulan Seismic Station, Earthquake Administration of Qinghai Province, Dulan 816100,Qinghai，China)

Abstract：This study introduces the principle and method for the use of differential global positioning system (GPS) in measuring azimuth in the China Geomagnetic Field Monitoring Network (CGFMN). We also present some azimuth measurement results and accuracy levels by geomagnetic observatories and geomagnetic survey stations, and offer some suggestions on how different geomagnetic observatories can measure azimuth in the future. We adopted two sets of differential GPS (model PROMAK 2 and PROMAK 100) including auxiliary devices antennas, cables, connected bases, and used one theodolite (model Mingeo) with an accuracy higher than 1 second. We installed the two differential GPS on two tripods, locating one near a mark (called station A) and the other alongside a fixed station room (station B) to measure the angle between geographical north (N) and a line AB (∠NAB).The entire measuring process ensures that the antennas and tripods remained stable and that the distance between stations A and B was more than 200 m. The GPS can receive satellite data until the transmission distance is more than 5 km, then the system turns off, and the above procedure is repeated. ∠NAB is computed using the two GPS data files using a special program. The theodolite was installed on a tripod near the mark to measure the angle between lines AP and AB (∠PAB, P is one of pillars), then it was moved to the pillar to measure the angle between the lines PA and PM (∠APM, M is one of marks). As such, the azimuth between geographical north (N) and the line from any pillar to any mark is determined through known angles. There are several methods for measuring azimuth. The proposed CGFMN azimuth measurement has the accuracy of the astronomical and differential GPS methods, less than 6″ of arc, which is higher than that of other equipment. Since 2001, the Lanzhou geomagnetic observatory has used differential GPS to measure the azimuth of 14 geomagnetic observatories and more than one thousand geomagnetic survey stations. Currently, the differential GPS method has replaced the CGFMN's astronomical method of azimuth measurement, using extensive GPS application. The main advantages of the differential GPS method over the astronomical method is that, in addition to having the same accuracy, it is free from the effects of weather conditions and human factors, all equipment can be operated easily by observers, and the data processing is completely computerized and has higher efficiency.

Keywords：ChinaGeomagneticFieldMonitoringNetwork;geomagneticfield;differentialGPS;geographicazimuth

0引言

地球磁场各成分起源不同，构成复杂，因此不同的研究领域对地磁场的分类不同。……