【摘要】 <正> 一、概述短波远距离传递时间信号主要通过天波传播,借助于电离层的反射来实现。当前,一般采用BIH所给出的经验公式计算短波传递时延值,其关系式为: τ=d/V_d 式中d为大圆距离;V_d=290-(a/(d×10^-3-b))（Km/ms）;a=139.41;b=2.90。用此公式计算发射台和接收台之间短波传播的时延值,认为是一个固定不变的值。现代的技术工作对短波的时间同步精度要求优于0.1ms的情况下,如果忽略了电离层高度变化的更多还原

【Abstract】 In this paper, a practical formula for calculating the time lag of sbort wave propagation being suited for a distance of less than 1000 km is given. This formula is derived directly based on the virtual height of ionosphere, the periodic variation of sunspot for 11 years, the annual and diurnal variations. It is the following τ=τ₀+τ+τ+τ（ms） τ₀=2.90 τ=+0.001012 τ=-0.048 cos （2πt+28°.4） τ=-0.110 cos （2πt_■-14°.3） where τ₀ is the time lag value calculated by the BIH experiential f ormula, τ, τ and τ₁ are the effects on the time lag caused by the relative number of sunspots, the annual and diurnal variations of ionosphere, respectively; and t_■ and t_d stand for the fractions of a year and a day separately. With the data obtained in Wu Chang Observatory of IGG, the formula was used in calculating a practical example. The compared results are given. The accuracy by this formula is better than that by BIH formula.更多还原