USA As Represented by Secretary of the Navy

Cabell N Pryor, Jr

Arthur D Delagrange

Wayne D Wilson

Edward H Hug

Michael H Stripling

An oscillator generates a fixed frequency ultrasonic output signal. After wer amplification this signal drives a transmitting transducer which projects an ultrasonic beam into water. Reflected signals are received by a receiving transducer and AGC preamplified. A chopper multiplies the received signal with the transmitted signal and generates an output signal if a target exists. To determine whether the target is a swimmer, this output signal is band pass filtered and amplified and then fed both to an automatic alarm and to a set of headphones. A human operator listening to the headphone output classifies the target and determines exact bearing.

Acoustic Doppler detector

An electrical circuit for measuring the phase difference between a pair of nput signals by uniformly limiting selected properties of the waveforms describing the input signals and modulating an output signal in dependence upon the duration of contrariety between the unlimited properties of the input signals whereby error in the output signal due to 'jitter' (i.e., abrupt, spurious variations in pulse amplitude or duration caused by superimposition of noise) is substantially eliminated. Various output means produce either a continuous wave analog signal or a digital bit signal in dependence upon the modulation of the output signal. Coupled ancillary circuitry monitors one input signal in comparison with the other input signal and provides an output signal signifying which input signal has a leading phase angle.

Waveform comparing phasemeter

A line spectrum detector to distinguish motor vehicles acoustically in the resence of background noise. The detector senses periodic signals, such as the firing rates of internal combustion engines, by using a swept phase-lock loop spectrum analyzer and passes the sensed signals to a logic network which measures the frequency stability of the sensed signal to distinguish motor vehicles from aircraft vehicles and the like.

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Silver Spring, MD, United States of America

Cabell N Pryor, Jr