US Government As Represented by the Secretary of the Army

Electric Power Research Institute Incorporated

Checkpoint Systems, Inc.

Zeger-abrams Incorporated

Burton S Abrams

Andrew E Zeger

Joseph L Rose

Gurvinder P Singh

Douglas S Makofka

Richard G Wheeler

Michael J Avioli

Luke C Chang

Louis A Mastrocola

Von C Ertwine

Stephen J Casey

Joseph M Cannon

Calvin R Waples, Jr

An improved electronic article security system is employed for detecting the presence of a security tag within a detection zone. The system includes a transmitter for generating electromagnetic energy and, in the disclosed embodiment, a single antenna for emitting electromagnetic energy received from the transmitter to establish an electromagnetic field within the detection zone and for sensing disturbances within the electromagnetic field, including disturbances resulting from a security tag within the detection zone. A receiver is provided for processing signals from the antenna relating to sensed disturbances and for providing output signals. A data processing and control section analyzes the output signals from the receiver and determines whether a sensed disturbance within the electromagnetic field is caused by the presence of a security tag within the detection zone. The output signals from the receiver are analyzed in accordance with predetermined criteria and pattern recognition techniques based upon receiver output signals which would be expected if a security tag were present in the detection zone to establish a security tag probability percentage.

Electronic article security system with digital signal processing and

Disclosed is a multiple-signal receiver system for direct sequence, code division multiple access (CDMA), spread spectrum (SS) signals. The receiver is structured to overcome inter-signal interference during signal acquisition and data reception even when the ratio of received signal powers exceeds the bandwidth spreading ratio of the signals. The receiver contains one processing channel for each signal in which correlation with the spread spectrum code of its particular signal is used to selectively isolate that signal so that its waveform parameters can be estimated, its data demodulated, and its waveform reconstructed. Each reconstructed CDMA waveform is individually adjusted in amplitude and phase to cancel its particular CDMA signal from the composite input of multiple CDMA signals. This receiver structure allows cancellation at the input of each receiver signal processing channel of all CDMA signals except the particular desired signal for that channel.

Multiple signal receiver for direct sequence, code division multiple

An ultrasonic return signal analyzing instrument and method including analog circuitry for making partial power measurements on two selected frequency bands of the frequency spectrum of an ultrasonic return signal waveform and digital circuitry for measuring selected features of the envelope of the ultrasonic return signal waveform. Digital waveform measurements are converted to analog signals and then combined in an algorithmic combining circuit to produce a test statistic signal. A decision circuit receives the test statistic signal and registers a decision on a characteristic of the structure under examination based on the value of the test statistic signal. The instrument includes a signal normalization circuit to normalize the ultrasonic return signal to a fixed peak value and includes a frequency up-converter in the normalizing circuit and frequency down-converters in the partial power measurement circuits for increasing the accuracy of peak detection in the normalizing circuit and envelope detection for the partial power band signals and the total power signal. The digital waveform feature measurement circuitry includes circuitry for measuring the rise time and duration time of the ultrasonic return signal envelope and logic is provided for handling two distinct return signal waveforms with rise time and duration time measurements being accomplished on the highest distinct pulse within the GATE signal window of the instrument. A GATE signal generated from the delayed GATE input of the pulser receiver of an ultrasonic instrument is utilized to GATE the various measurement functions so that measurements will be made only on the selected segment of the ultrasonic return signal waveform desired to be analyzed. A Fisher linear discriminant function is used as the algorithm in connection with analyzing ultrasonic return signals from stainless steel pipe having possible intergranular stress corrosion cracking conditions therein.

System and method for measuring ultrasonic return signals

Disclosed is an in-band, non-sampling, real time VHF radio relay or signal epeater for use in two-way, multi-hop remote sensor data links. Each signal repeater comprises a transceiver which includes interference cancellation circuits for preventing the high level signal produced by the radio repeater's transmitter section from desensitizing the low noise RF amplifier circuitry incorporated in the front end of the radio repeater's receiver section. Such apparatus is utilized to implement a remote sensor data collection network consisting of a plurality of subject radio repeaters and several sensors normally arranged in groups. The data which flows over the relay network can either originate at the sensors and flow to a read out station or it may originate at the read out station and flow to the sensors. Sensor originated information may be either digital or analog, or both, while read-out station originated information is digital only. The relay operates with either analog or digitally-modulated signals. When used with an omnidirectional antenna, it is not direction-preferential.

VHF Sensor in-band radio relay

Growing community of inventors

Wyndmoor, PA, United States of America

Burton S Abrams