Apparatus and method for performing open loop tracking of a signal

摘要

Apparatus for performing open loop tracking of a signal in a radio occultation instrumentation system including a first satellite arranged with a transmitting means arranged for transmitting a signal with well defined carrier frequency and a second satellite arranged with signal receiving means receiving said signal, wherein said transmitted signal has a ray path from said first satellite to said second satellite which descends into and ascends from the atmosphere, said apparatus including means for providing a control signal to a frequency control unit for signal acquisition included in said receiving means, means for receiving information I(x,v) regarding the position and velocity of the first and second satellite; arrangement for providing a prediction of Doppler shift displacement of a transmitted signal in such a radio occultation system; and method for determining atmospheric conditions from information of Doppler shift displacement in a radio occultation instrumentation system.