Doppler radar/ultrasonic hybrid height sensing system
AssigneeThe United States of America as represented by the Secretary of the Army
InventorsReed W. Hoyt, John F. Lanza
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Abstract
A height measurement system uses an inexpensive ultrasonic height measuring evice to provide an apparent height of a descending airborne object. To compensate for movement of the object during the ultrasonic measurement, a Doppler radar velocity measuring device determines the vertical velocity in a short measurement period. The measured vertical velocity is used to determine the vertical distance travelled during the ultrasonic measurement and to compensate therefor by converting the apparent height to a true height of the descending object. Updates of the true height may be obtained by storing the vertical velocity and retrieving the vertical velocity for multiplication by a time value to obtain an updated value of the true height.
Claims10
Hybrid distance measuring apparatus for correcting ultrasonic distance measurements comprising:
- ultrasonic means for measuring an apparent distance between first and second objects by transmission and reflection of ultrasonic signals;
- radar means for measuring a relative velocity between the first and second objects by transmission and reflection of radar signals;
- and
- compensating means for compensating the apparent distance measured by said ultrasonic means by modifying the apparent distance in accordance with the relative velocity measured by said radar means and for producing an indication of true distance between the objects.
Hybrid height measuring system for correcting ultrasonic height measurements comprising:
- ultrasonic means for measuring a height between a descending airborne object and a landing surface by transmission and reflection of ultrasonic signals;
- radar means for measuring a vertical velocity of the descending object by transmission and reflection of radar signals;
- and
- compensating means for compensating an apparent height of the descending object measured by said ultrasonic means by modifying the apparent height in accordance with the vertical velocity measured by said radar means and for producing an indication of true height between the objects.
Dependencies are inferred from the claim text.