Abstract: A system for illuminating a light emitting panel for backlighting a visual display positions the panel behind the visual display at a front wall of a processor cabinet. The light emitting panel has at least one layer of optical fibers which extend from the panel and are bundled and terminated in one or more receptors which are mounted in the cabinet remote from the panel and visual display. A cover is hinged to the cabinet and mounts a light source in operative alignment with the receptors when the cover is closed to illuminate the panel and display. The cover can be swung open to position the light source in a maintenance position in which light bulbs of the source can be removed and replaced.

Abstract: A communication module has a backplane interface circuit that enables the module to communicate with other components of the programmable controller, and has a network interface circuit which sends and receives messages via a serial communication link. A memory within the module stores a designation of a starting time, a designation of a length of a message repeat interval, and a file of message information. A clock circuit determines when the starting time occurs and thereafter determines the expiration of each successive occurrence of the message repeat period. A control mechanism responds to the clock circuit determining an occurrence of the starting time or determining an expiration of a message repeat interval, by operating network interface circuit to transmit a message, that contains the message information, over the serial communication link.

Abstract: A microwave receiver self-test capability which includes at least two channels with each channel including an amplifier and an IF receiver, the microwave receiver, also including a local oscillator capable of mixing with either of said channels for providing an IF signal and a data modulated signal source capable of coupling with said local oscillator through one channel of said microwave receiver and thereby, generating a microwave test signal for the other of said channel of said microwave receiver.

Abstract: An optical beamforming network is provided for controlling the RF radiation pattern of a phased array antenna. Light from a first laser is modulated by a spatial light modulator that is user-programmed with the desired far field radiation footprint. The modulated light beam is directed through a Fourier transform lens and onto a beam splitter where it is combined with light from a second laser that is frequency offset by the RF center frequency of the antenna. Light from the beam splitter is recovered by first and second fiber optic bundles. Each optical fiber leads to a corresponding photodetector that detects the beat frequency produced by the two frequency offset light beams. The outputs of corresponding photodetectors of the two fiber optic bundles are combined to control the radiation of a corresponding radiation element of the phased array. The use of two sets of optical fibers and photodetectors improves the signal-to-noise ratio of the system.

Abstract: A 20 to 500 MHz directional coupler for use in a high power RF system uses a pair of transmission line sections electrically interconnected in series by their shield terminals. The primary signal is passed through one of the line sections, and the second section is connected to ground through a resistor. The forward voltage is thus the voltage between the shield of the first line section and ground across the second line section.

Abstract: An automatic gain control (AGC) amplifier, which may be fabricated as a monolithic integrated circuit, provides linear gain response in dB over a wide dynamic range. The AGC amplifier comprises multiple cascode amplifier stages connected in cascade to provide high power handlign capability and high gain. A control voltage is input to a linearization circuit which provides an output to an operational amplifier that functions as a voltage controlled voltage source (VCVS). The VCVS produces a conditioned control voltage which is fed back to the linearization circuit and provided to each of the cascode amplifier stages. The conditioned control voltage provided to each amplifier stage causes current to be removed from the cascode amplifier, thereby lowering its gain. The overall gain of the AGC amplifier is linear in dB with respect to linear changes in the control voltage applied to the linearization circuit.

Abstract: There is disclosed an inspection system which allows the visual inspection of an item and the automatic recordation of the position of a defect or other inspection characteristic in the plane of inspection. In the visual inspection of an electronic circuit card, the card is inserted into a holder which maintains the card in a reference plane which is fixed relative to a plurality of sonic emitters. A microscope or other viewing device is fixed in a predetermined position on a support structure and includes cross hairs or other indicia to allow the visual identification of a particular point on an item that is to be visually inspected. A plurality of sonic receivers are coupled in predetermined positions on the support structure to receive sonic energy generated by the emitters.

Abstract: A system and technique is disclosed which enables the production of in-phase and quadrature phase signals useful for deriving phase difference measurements. In an in-phase and quadrature phase difference measurement system, the phase shifter employed must receive an input signal and produce an output signal which is 90.degree. out of phase and equal in amplitude to the input signal over the full frequency range of the input signal. This is accomplished by using a phase locked loop which locks onto the input signal and uses the output of a voltage controlled oscillator located in the loop to derive the sine and cosine of the input signal. The resulting sine and cosine outputs are then 90.degree. out of phase and form in-phase and quadrature phase signals which have equal amplitudes. These two signals maintain lock over the frequency range of the input signal and may be used as inputs in the phase difference measurement system.