Application of global positioning system in surveying project of high voltage transmission line in Tangshan City,Hebei Province,north China.

This paper presents an application of static GPS in the surveying of high voltage transmission line in Tangshan City,and focuses on the design of static control network in line survey,field operation and accuracy analysis.Through data union calculation and analysis,measures to improve data accuracy of interior and field survey were proposed.For example,in the design of static control network,the impact of Nnicom Mobile signal towers,a large area of water,high buildings and tall trees to GPS satellite signal should be considered.To ensure a strong GPS signal,base stations are generally set up in high elevation areas,such as on top of buildings,mountains and open land.To ensure the accuracy of data,a series of measures are taken to control errors in a permitted scale.A careful and thoughtful field survey of GPS is a precondition to ensure data accuracy,and the data process is the final test to check data accuracy.For the data that cannot be obtained in field survey,an eccentric observation is carried out.A model and factors affecting eccentric observation on accuracy are presented.