Radiosonde

Claim 1

An altitude measuring system for a radiosonde comprising: means for identifying the exact geographic location of said radiosonde, said geographic location consisting of the latitude and longitude of said radiosonde; means for transmitting a timing signal from a reference station of known geographic location and known altitude to said radiosonde; means for returning said timing signal from said radiosonde back to said transmitting means; means for receiving said returned signal located with said transmitting means at said reference station; means for communicating said radiosonde's geographic position from said identification means to said reference station; a computer connected to receive said transmitted signal, said return signal, and said radiosonde's geographic position, the time difference between said transmitted signal and said return signal proportional to twice the distance D between said radiosonde and said remote reference station said computer programmed such that the distance D is determined and the height ΔZ of said radiosonde above or below said reference station according to the equation ΔZ=±√D.sup.2 -X.sup.2 -Y.sup.2 is determined where ΔZ=the difference in altitude between the reference station and the radiosonde. D=the distance between the radiosonde and the reference station, ΔX=the difference in latitude between the reference station and the radiosonde, and ΔY=the difference in longitude between the reference station and radiosonde; and means for sensing motion are connected to said computer to evaluate whether ΔZ is positive or negative.