Abstract: A space-borne interferometric radiometer for imaging a radiation emission from a target scene (ED), comprising a plurality of receiving elements arranged in a two- or three-dimensional array (REA), a first signal processor (SP1) for computing a two-dimensional set of samples of a visibility function by pair-wise cross-correlating signals received by the receiving elements; and second signal processor (SP2) for reconstructing an image from the samples of the visibility function. The radiometer is further characterized in that it has the ability for rotating the two- or three-dimensional array (REA) about a rotation axis (z) which is substantially directed toward the target scene (ED) and in that the second signal processor (SP2) is adapted for reconstructing the image from a plurality of two-dimensional sets of samples of the visibility function corresponding to different rotational positions of the rotating two- or three-dimensional array (REA) of receiving elements.

Abstract: A space-borne interferometric radiometer for imaging a radiation emission from a target scene (ED), comprising: a plurality of receiving elements arranged in a two- or three-dimensional array (REA); first signal processing means (SP1) for computing a two-dimensional set of samples of a visibility function by pair-wise cross-correlating signals received by said receiving elements; and second signal processing means (SP2) for reconstructing an image from said samples of said visibility function; characterized in that it further comprises means (ROT) for rotating said two- or three-dimensional array (REA) about a rotation axis (z) which is substantially directed toward said target scene (ED); and in that said second signal processing means (SP2) are adapted for reconstructing said image from a plurality of two-dimensional sets of samples of said visibility function corresponding to different rotational positions of said rotating two- or three-dimensional array (REA) of receiving elements.

Abstract: A radio occultation instrumentation system includes a first satellite arranged with a transmitter for transmitting a signal with a carrier frequency and a second satellite arranged with a receiver for receiving the signal. The receiver receives information I(x,v) regarding the position and velocity of the first and second satellite and provides a prediction of the Doppler shift displacement of the carrier frequency of the signal for use in tracking the signal. The predicted Doppler shift displacement is also used to determine atmospheric conditions.

Abstract: 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.

Abstract: An inexpensive high gain antenna for use on terminals communicating with low earth orbit (LEO) satellites which include an elevation table mounted for arcuate movement about a transverse axis on an azimuth turntable mounted for rotational movement about a central axis. A plurality of antenna elements forming a phased array antenna are mounted on the top of the elevation table and have a scan plane which is parallel to and extends through the transverse axis of the elevation table. The antenna may be both mechanically and electrically scanned and is used to perform handoffs from one LEO satellite to another by positioning the elevation table of the antenna with its boresight in a direction intermediate the two satellites and with the scan plane of the antenna passing through both satellites. At the moment of of handoff, the antenna beam is electronically scanned from one satellite to another without any loss in data communication during the process.