Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.