Abstract: Considering the generation mechanisms of the atmospheric gravity waves and measurement techniques for TID_s, some useful rules for explaination of the measurements are drawn. It is shown that: TID_s consist of two harmonic waves which are orthogonal to each other, and both the measurement techniques for TID_s i.e. the total electron content measurement and the electron density measurement are equally effective. Accordingly inversion formulas for determination of the phase velocity of TID_s from radio astronomical data are derived, and the suppressing effects on wave amplitude are discussed.