USA As Represented by Secretary of the Navy

Applied Acoustic Research, Inc.

Lord Corporation

Lynn A Poole

Glenn E Warnaka

Robert D Marciniak

Jiri Tichy

Dale H Hoover

Harry M Crain

A low power, wide-dynamic-range, signal compressor is suitable for operat from batteries. The compressor input is compatable with most sensors, resistive, capacitive or inductive and it is capable of compressing 150 db of input dynamic range into a 6 bit digital or 40 db analog signal. The output from the compressor is single valued and satisfactory for driving standard telemetry equipment.

Wide dynamic range, low power, analog-to-digital receiver

A conventional voice microphone placed in non-critical spaced relation to a source of intelligible speech sound while exposed to an acoustical field of ambient noise, electrically transmits output signals attenuated under control of a signal processing controller to which a sampled input of noise signals is fed by a reference microphone exposed to the same acoustical noise field as the voice microphone for audio reproduction of the speech sound without background noise by programming of the controller.

Noise reducing system for voice microphones

The acoustical energy output of a source is varied in frequency between limits to sweep a frequency band encompassing cavity resonance conditions which depend on the quantity of a fluent material within a tank excited by such acoustical energy. The volume of the fluent material is calculated from the excitation frequency registered during verified detection of resonance conditions, based on abrupt changes in signal characteristics and stored data relating to the geometry of the acoustic sensor arrangement through which the tank interior is monitored.

System for monitoring fluent material within a container

A remote monitor unit comprising a battery pack, a regulated power supply, program control board, a receiver AD board, a plurality of memory boards and a transducer, all housed in a water tight enclosure. External control or data communication links are unnecessary with the remote monitor unit. Once the device has been activated and placed in its housing, a programmable time delay feature allows the user to place the unit at a selected site in advance of the start of the recording period without wasting any data storage capability. When deployed and activated, analog data from the transducer is converted to digital form and silently recorded by storing it in a non-volatile memory medium on the memory boards. The digitized information is later retrieved from the memory boards by micro, mini or main frame computer and stored on magnetic tape for subsequent processing. The memory boards are then erased by exposure to ultra-violet light and reused.

Remote monitor unit

An active attenuator is provided for the attenuation of a relatively broad band of lower frequency vibration such as sound waves from a given source, by the introduction of cancelling vibration having the mirror image amplitude and phase characteritics of the source vibration. The active attenuator herein includes an input sensor for detecting the source vibration, a cancelling speaker for generating cancelling vibration, an error sensor for sensing the combination of source and cancelling vibration, and an electronic controller coupled to the input sensor, cancelling speaker and error sensor. The electronic controller includes an adaptive cancelling filter which employs a deterministic algorithm operable to accommodate the propagation delays of the vibration sensed by the input and error sensors, and produce an output to activate and control the cancelling speaker for the production of cancelling vibration.

Active acoustic attenuator

A beam-former for sampling and digitizing a sonar signal preparatory to F Fourier Transformer (FFT) processing comprising an array of ceramic sensors forming a series of rows and columns, a sampling transformer for each row and each column for sampling the weighted sum of the signals from the sensors in each row or column, a log compressor for each sampling transformer for compressing the amplitude of the sampled signal, an analog-to-digital (A/D) converter circuit following each log compressor for sampling and digitizing the compressed signals under the control of a counting circuit so that the log compressor outputs are sampled at prescribed times in relation to each other so as to impart a time or phase shift to the digitized outputs to effect a beam tilting, a decompression circuit for decompressing the time shifted signals, an accumulator for adding the samples from each row and column, and a shifting circuit for shifting the accumulated signal up or down to make it compatible with the FFT circuit.

Beam-former for FFT-based signal processor

A combined analog and digital ratio detector circuit produces a gated out whenever the average amplitude of an information pulse exceeds a fixed preset threshold in the presence of an interfering noise background. The circuit also has the capability of tracking the average value of the noise to null it out, thereby maintaining the preset signal-to-threshold ratio over a wide range of slowly varying noise amplitudes. The circuit's functional breakdown is as follows: (1) an input operational amplifier has a time constant related to the information pulse duration; (2) a noise voltage tracking and nulling loop has a time constant related to the background noise characteristics; (3) a logic interface between a system clock and a counter (part of item 2) prevents 'racing'; and (4) an adjustable threshold gate sets the false alarm rate at an acceptable information retrieval probability.

Growing community of inventors

State College, PA, United States of America

Lynn A Poole