Communications – electrical: acoustic wave systems and devices – Echo systems – Returned signal used for control
Patent
1990-05-29
1991-10-22
Pihulic, Daniel T.
Communications, electrical: acoustic wave systems and devices
Echo systems
Returned signal used for control
367 99, G01S 1500
Patent
active
050602055
ABSTRACT:
A distance sensing system includes an ultrasonic transducer, a transceiver and a microcontroller-based signal processing unit. The transducer periodically generates and directs towards the terrain a dual frequency ultrasonic signal. Echo signals from the ground and/or any intervening crop or trash are reflected back to the transducer and are processed. The system generates amplified and filtered echo envelope signals. Leading and trailing edge times are determined as the times the echo signals cross a threshold value which is a certain proportion of a maximum echo amplitude value. A near distance value is derived from the leading edge time of the first echo which exceeds a minimum amplitude. A far distance value is determined as the trailing edge time of the last echo signal which has an amplitude which exceeds a certain value. Multiple echo time and amplitude values are derived from the maximum amplitude echo. These values are used to prevent echoes which occur after the multiple echo time with less than a certain amplitude from being used in the determination of the far distance value. This far distance value represents the distance to ground and weaker, earlier echoes from trash or crop and later, multiple echoes may be ignored.
REFERENCES:
patent: 3454922 (1969-07-01), Dory
patent: 4414792 (1983-11-01), Bettencourt et al.
patent: 4573124 (1986-02-01), Seiferling
patent: 4760419 (1988-07-01), Fujiwara et al.
patent: 4910717 (1990-03-01), Terry
Deere & Company
Pihulic Daniel T.
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