Automatic noise suppression system for acoustic height sensor
First Claim
1. In an ultrasonic distance sensor adapted to receive bursts of ultrasonic wave energy reflected from a distance surface, the combination of means responsive to said received bursts for producing a pulsed signal representative of said received bursts, means responsive to said pulsed signal for producing an electrical signal proportional to the range of said distant surface, sample and hold circuit means, means for applying said electrical signal proportional to range to said sample and hold circuit means such that the sample and hold circuit means can be actuated to store the previous value of said electrical signal proportional to range, means for detecting the presence of noise of predetermined magnitude in wave energy received by said sensor, means coupled to said detecting means and operable when noise is detected for actuating said sample and hold circuit means to store said electrical signal proportional to range while preventing passage of pulsed signals to said means for producing a signal proportional to range, and wherein said means for producing an electrical signal proportional to range includes a variable gain amplifier for amplifying returned bursts of ultrasonic wave energy, means for varying the gain of said variable gain amplifier as a function of the range of said distant surface, and second sample and hold circuit means for maintaining the gain of said variable gain amplifier constant when noise of predetermined magnitude is detected by said detecting means.
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Abstract
An acoustic height sensor, particularly adapted for use in the foil-borne mode of operation of a hydrofoil, wherein sensitivity to noise pulses is materially reduced or essentially eliminated by monitoring for noise levels capable of producing interference and, if the noise persists for a sufficiently long period, suspending processing of any signal returns until the noise ceases. In the meantime, and as processing of signal returns is suspended, sample and hold circuitry maintains the output of the system at its previous level until the noise abates.
17 Citations
4 Claims
- 1. In an ultrasonic distance sensor adapted to receive bursts of ultrasonic wave energy reflected from a distance surface, the combination of means responsive to said received bursts for producing a pulsed signal representative of said received bursts, means responsive to said pulsed signal for producing an electrical signal proportional to the range of said distant surface, sample and hold circuit means, means for applying said electrical signal proportional to range to said sample and hold circuit means such that the sample and hold circuit means can be actuated to store the previous value of said electrical signal proportional to range, means for detecting the presence of noise of predetermined magnitude in wave energy received by said sensor, means coupled to said detecting means and operable when noise is detected for actuating said sample and hold circuit means to store said electrical signal proportional to range while preventing passage of pulsed signals to said means for producing a signal proportional to range, and wherein said means for producing an electrical signal proportional to range includes a variable gain amplifier for amplifying returned bursts of ultrasonic wave energy, means for varying the gain of said variable gain amplifier as a function of the range of said distant surface, and second sample and hold circuit means for maintaining the gain of said variable gain amplifier constant when noise of predetermined magnitude is detected by said detecting means.
Specification