On the Dynamic Adjustment of Repeating Levelling Nets Covering a Vast Area

In order to solve the problem of dynamic adjustment of repeating leveling nets covering a vast area,several adjustment programmes are suggested,By way of calculating examples,these programmes are analyzed and compared in respect to the average error of adjusted differences of heights and velocity values,as well as the efficiencies of convergence of calculation,In this way,a rigorous method——the progressive approximation adjustment of the velocity value and the difference of heights——is suggested,which may suit well the condition of our country.Since the difference of heights used in the adjustment may come from the levellings of different orders,the question,of reasonable weighting of observations is thus emphatically discussed,and a method of weight determination is proposed.Besides,according to the result of the calculating example,a discussion is made about how to determine the mean year of the different observation periods and how to choose the leveling lines.A formula of weight reciprocal of the adjusted velocity value is also given in order to calculate the mean error of the adjusted velocity value of some bench marks.