| 摘要 |
A continuous wave radar altimeter comprises a memory (24, 26), means for storing in the memory in digital form an array of return signals representative of the variation of reflected amplitude with path length, means (27), for addressing the memory for identifying a peak return representative of the highest objects on the terrain, means (28) responsive to the array for determining the signal-to-noise ratio thereof, and means (29) responsive to the height at which the said peak return occurs and to the signal-to-noise ratio to determine a "centre of area" height representative of the lowest surface on the terrain. The altimeter thus provides not only the peak level, representing for example the tops of trees and buildings, but also the ground level.
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