Abstract: A microwave cooking system comprising a thermally insulated holder for food bodies having a thermally reflective shield for reflecting thermal radiation from the food bodies to thereby reduce the loss of heat by radiation through the thermal insulation layer while providing for propagation of microwave energy into the food body through the thermal insulating portion of the food holder.

Abstract: A reflectometer for precisely measuring the reflectivities of mirrors by performing two sequential measurements each of which is related to a different function of the reflectivities of a reference mirror and the mirror under test. For the first measurement, the two mirrors are arranged so that a beam of light is reflected alternately from the reference mirror and from the test mirror to an output detector to produce an output signal related to the difference of the reflectivities. In the second measurement, the mirrors are positioned so that the beam passes to the output detector directly and, alternately, after reflection from first the reference mirror and then the test mirror, thereby producing an output signal related to the product of the reflectivities. The reflectivity of the test mirror is then calculated from the two output signal quantities.

Abstract: A combination microwave and convection oven in which a gas burner positioned outside the oven provides heated combustion products which are drawn from the burner area along with vapor from an outlet of the oven by a blower system and the combined output of the blower system is blown into the oven through an oven inlet region in the oven wall. Both the oven outlets and the oven inlet are formed of holes substantially less than one-half wavelength in diameter. A predetermined portion of the blower output system is blown through an exhaust vent thereby creating slight negative pressures in the oven and in the burner plenum to accurately control the air flow through the burner.

Abstract: This system accepts compass outputs from a wide variety of compass output devices such as stepper and synchro devices having different coupling ratios, supply voltages and carrier frequencies. The system then, as part of a PPI radar system, electronically converts these compass outputs without the usual intermediary electromechanical devices into real-time analog reference signals properly phased with respect to the radar timing to provide an electronically stabilized PPI. This is achieved by comparing the points of equal amplitude of any two phases of gyro compass synchro output signals and using these major transition points to provide a digital code indicating the angular position of the gyro output shaft; a microprocessor then transforms the code, by comparison with a previously stored position code into coded position change signals which are then used to change a stored angular value, representing the course of the ship.

Abstract: A tailbiter and open magnetron protection circuit for a radar pulse modulator having an extra winding on the modulator output transformer which combines a circuit to shorten a short range radar pulse with a circuit for applying a substantially constant load to the modulator when the magnetron is open or inactive. The extra winding on the transformer is connected in series with a saturable reactor which prevents shorting the desired short pulse width and stores undesired pulse energy in a capacitor and an SCR tailbiter circuit to short the excess pulse energy to ground in the interpulse period upon actuation of the SCR. Also included in the tailbiter circuit is an alternate path through a voltage divider and zener diode to the SCR gate which, whenever the magnetron is open or does not fire, a voltage build-up exceeding the zener voltage triggers the SCR gate circuit to maintain a substantially constant load on the primary of the modulation transformer.

Abstract: A microwave oven having a rotating radiator supported on a conductor extending through an aperture in a wall of the oven. The radiator is made up of a plurality of separate radiating elements supplied with microwave energy from said conductor via separate strip lines. A conductor of each of the strip lines rotates with the radiator and with respect to a ground plane which is common to all the strip lines and is formed by the wall of the oven containing the aperture. The radiating elements simultaneously radiate separate patterns into the oven.

Abstract: A microwave convection oven in which a gas burner positioned outside the oven cavity has its combustion products circulated through the oven through screens for preventing escape of the microwave energy from the oven cavity with the burner being of the multi-ported type providing high burner density and having secondary air closely adjacent all portions of the burner to reduce its incondescent flame length while permitting the burner to be positioned in a region between the screened vapor outlet region the oven and the inlet of a blower system for mixing the output of the burner with the vapor drawn from the oven thus the temperature of the vapor outlet region is maintained below that at which ionization of the vapor being drawn from the oven might produce leakage of microwave energy through the screen.

Abstract: An optical encoder device for use with a variable range mark display. An operator rotatable cylindrically shaped encoder wheel with longitudinal slits is panel mounted. Two light-emitting diodes are positioned outside the wheel opposite two phototransistors located inside the wheel. The light-emitting diode-phototransistor pairs are spaced at a forty-five degree angle from one another from the center of the wheel. Rotation of the wheel interrupts the light path between the light-emitting diodes and phototransistors producing two output signals. For one direction of rotation the first signal leads the second while for the other direction of rotation the first lags the second. A circuit is disclosed which determines from the output signals the direction of rotation and produces a count indicative of the amount of rotation.

Abstract: A laser gyroscope having a multi-frequency ring laser resonator containing a gas laser energized by electric discharge through a gaseous laser medium from two anodes to a common cathode positioned outside the lasing passage and communicating therewith through a narrow bore having a nonuniform constant magnetic field applied to the gaseous discharge in said bore to suppress high frequency gas discharge oscillations in the laser.

Abstract: A method and apparatus for fracturing and/or heating subsurface formations wherein an alternating current electric field is produced in the frequency range between 100 kilohertz and 100 meghertz between electrodes spaced apart in the formation and a radio frequency generator supplying a voltage between said lines with suitable loading structures tuned to the frequency of the generator to resonate the electrodes as a parallel wire transmission line which is terminated in an open circuit and produces a standing wave having a voltage node at the end of the line.

Abstract: An overload protective circuit for direct current switching or flyback power supplies which senses for build up of internal transistor stress during operation of the main power transistor output stage. Normally, setting an internal overload limit for the main power transistor dissipation is difficult to achieve because the load current to be sensed is out of phase with input driver current. The invention provides for sensing a change in base drive input voltage during a departure from normal operating saturation of Baker clamped main power transistors and initiating a reduction in the width of the drive pulses to reduce internal transistor stress and to reduce power input prior to transistor damage.

Abstract: A combination electric heat and microwave oven employing a common cavity for cooking food with either microwave energy, electric resistance heating, or both in which the oven is supplied with microwave energy through a rotating multi-port radiator having a plenum fed from a magnetron through a waveguide and a coaxial line whose outer conductor extends into the plenum and whose central conductor supports said radiator.

Abstract: A system for forming a beam of radiant energy which is incident upon or radiated from an array of radiating elements such as sonar transducers. As a wavefront progresses across the array, samples of signals received by individual ones of the transducers are selected in accordance with specific beams to be formed, the selected samples being summed together through a sequence of partial summations until a complete summation of a sample of a beam is obtained. The sequence of partial summations is initiated successively for each output sampling interval. For a long array, wherein the transit time of a wavefront across the array is longer than the intersample interval, a plurality of the sequences are generated concurrently. All partial sums for all beam samples are generated periodically at the output sampling rate and are stored in a memory.

Abstract: A radar system in which the time duration of video pulses corresponding to echo returns is increased as a direct function of the range of the return. On a PPI visual indicator, the visibility of long range targets is thus enhanced by increased size without distorting the display of short range targets and clutter.

Abstract: A bright display radar system having anticollision capabilities in which received signals are digitized at a rate determined by a radar range setting and displayed at a constant relatively slow rate independent of the range setting. A computer based anticollision unit operates in response to the relatively slow digitized received signals so that targets may be tracked equally well at short and long ranges. Two sets of operator actuable switches are provided for controlling the anticollision unit. A first set of switches is provided which correspond directly to the most commonly used computer operating functions. The second includes an alphanumeric keyboard which may be used to actuate subroutines stored in a physically separate read-only memory which operates only in response to the alphanumeric keyboard.

Abstract: A high voltage power supply system particularly adapted for rapid switching of high voltage applied to an anode of a beam penetration color cathode-ray tube. Energy for making the rapid transition between voltage levels is stored in two energy storage inductors, one for upward transitions and the other for downward transitions. When it is desired to change the voltage applied to the cathode-ray tube, the appropriate one of the storage inductors is coupled through a controlled switch to the anode causing the voltage applied to the anode to change at a rapid rate. The voltage rises until the desired voltage level corresponding to a desired output color is reached at which time the switch is turned off and the storage inductor recharged. A tracking high voltage supply maintains the anode at the predetermined voltage level once that level has been reached.

Abstract: A variable range marker device for use with a PPI radar with digitized video displayed in non-real time. The position of the range marker is initially operator determined by rotation of a knob mechanically linked to an optically encoded disc. Optical sensors produce a digital output indicative of the disc rotation angle and range mark position as a distance from the center of the radar display screen. A counter is preset with the digital output at the start of each sweep and decremented once each range cell until a count of zero is reached at which time an unblanking pulse is produced. A numeric display of range is produced by dividing the number of range cells to the range mark by the range setting and displaying the result with a three digit LED display.

Abstract: A radar system with digitized video having a digital interference rejection circuit for eliminating spiral interference caused by nearby radar transmitters operating in the same frequency band. Video signals from each sweep are stored in a random access memory. A comparison is made between adjacent range cells in the present "live" video signal and the video signal from the previous sweep. The output video signal to the display device is inhibited should the comparison indicate the presence of interference.

Abstract: A radar system having an adaptive compass drive capable of operation over a wide variety of compass outputs and supply voltages and frequencies. For compass outputs in the form of multi-phased analog signals, a digital phase detector converts the signals to a series of digital pulses which are used to operate a three-phase to UP-DOWN pulse converter. If the gyro compass output signals are in the form of overlapping digital signals, the converter changes the signals directly to a sequence of UP or DOWN pulses. The UP-DOWN pulses are used to operate a binary counter which operates the phases of a multi-phased stepper motor which is coupled to the true bearing scale of the radar system the output of which may also be used to operate a north stabilization synchro converter for the radar display.

Abstract: A radar system having the radar pulse rate controlled directly from an indicator unit. Separate modulator-transmitter-receiver and digital video processor indicator units are provided. A radar trigger pulse is produced by the processor unit in synchronism with the processor clock at a rate determined by the radar range setting. An acknowledge signal is produced in turn by the modulator-transmitter-receiver in accordance with an activating signal in the modulator and fed back to the indicator unit to start video signal digitization and the CRT sweep. Jitter between the start of the radar return signal and the radar sweep are eliminated.