Remote sensing apparatus for satellites
First Claim
1. Remote sensing apparatus for use on board a satellite for sensing the differing values of a variable geophysical parameter in a plurality of measurement cells definable in at least one elongated region of the surface of the earth adjacent to the satellite ground track, said variable parameter altering the back-scatter coefficient of radar signal echos, said apparatus comprising:
- transmitter-receiver means for illuminating said region with radar signals and receiving echos therefrom, said transmitter-receiver means including at least one frequency scanning antenna means, said transmitter-receiver means including control means for energizing said antenna means to transmit a succession of radar beams, each of said radar beams being transmitted at a predetermined angle of incidence to the earth'"'"'s surface and illuminating a cell in said region, each of said radar beams having a predetermined frequency and transmission power output selected in accordance with the transmission angle of incidence, said control means energizing said antenna means at substantially the same transmission power for time periods of differing lengths, thereby to control the transmission power output of said antenna means for each of said radar beams, and said transmitter-receiver means including signal processing means coupled to said antenna means for obtaining back-scatter coefficient properties of the radar signal echos and the values of the variable geophysical parameter.
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Accused Products
Abstract
The invention relates to remote sensing from a satellite of a parameter in one or more regions on the ground adjacent the satellite ground track by radar transmission. The purpose of the invention is to reduce energy consumption and optimize measurement accuracy. A transmitter antenna generates a plurality of pencil radar beams which illuminate respective cells of the region. A control means successively energizes the antenna at respective frequencies for respective pulse durations and for respective number of pulses. The invention is particularly appliable to scatterometer apparatus for responding to wind speed and direction by sensing radar backscatter from sea.
21 Citations
9 Claims
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1. Remote sensing apparatus for use on board a satellite for sensing the differing values of a variable geophysical parameter in a plurality of measurement cells definable in at least one elongated region of the surface of the earth adjacent to the satellite ground track, said variable parameter altering the back-scatter coefficient of radar signal echos, said apparatus comprising:
- transmitter-receiver means for illuminating said region with radar signals and receiving echos therefrom, said transmitter-receiver means including at least one frequency scanning antenna means, said transmitter-receiver means including control means for energizing said antenna means to transmit a succession of radar beams, each of said radar beams being transmitted at a predetermined angle of incidence to the earth'"'"'s surface and illuminating a cell in said region, each of said radar beams having a predetermined frequency and transmission power output selected in accordance with the transmission angle of incidence, said control means energizing said antenna means at substantially the same transmission power for time periods of differing lengths, thereby to control the transmission power output of said antenna means for each of said radar beams, and said transmitter-receiver means including signal processing means coupled to said antenna means for obtaining back-scatter coefficient properties of the radar signal echos and the values of the variable geophysical parameter.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
Specification