Abstract: A method and apparatus for classifying and/or identifying materials by means of their spectral response to gamma radiation. Classification is carried out by irradiating multiple different samples with gamma radiation, detecting a spectral response in the backscatter direction, sorting the spectral response into energy bands and selecting a combination of energy bands to define a relationship that best distinguishes between clusters of spectral responses for different material classes. Two or more of the energy bands may overlap.

Abstract: Methods and apparatus for detecting a modulating element of an object are described in which signal values are obtained from one or more optical detectors. A determination is made if there is a time dependent variation in the obtained signal values at the one or more optical detector and a modulating element is detected based on the determination.

Abstract: Methods and apparatus for detecting a modulating element of an object in a scene are described in which an element in a scene is illuminated with a modulated light source. A signal is obtained from an optical detector based on light received from the illuminated element. An intermediate frequency signal is detected from the signal obtained from the optical detector, the intermediate frequency signal being related to a frequency of the modulated light source and a frequency of modulation of the element within the scene. The modulating element is detected based on the intermediate frequency signal.

Abstract: A system for selectively interconnecting a plurality of audio/video sources and a plurality of audio/video communication devices including a single switch, a mixer to combine the audio and video signals as a single signal from a source to the switch and a modulator for modulating the video signal after the switch for optical transmission to the communication devices. The modulated audio and video signals directly drive an optical transmitter as a composite signal. A programmable interface is provided at the sources and at the communication devices for translating system remote control signals to source and communication device control signals for the connected device. The interface provides ALL CALL overrides.

Abstract: An apparatus for providing video signal synchronized operation between two or more video signal originating devices, such as video color cameras, one operating as a master, and the other one or more video cameras or devices operating as slaves or masters, is described. The apparatus takes the latch output of the master camera channel and derives a positive-going ramp one horizontal line long. The slave latch output is also caused to form a sample pulse. The master ramp and slave sample pulse are compared and the resultant positive correction voltage is applied to the voltage controlled oscillator of the slave. The apparatus develops positive error pulses if the master and slave video signals are not synchronized.