Abstract: The diode bias input terminals of an IMPATT microwave power combiner are resistively coupled to a common floating node to provide stabilization of the operating points of the individual IMPATT diodes, thus minimizing the tendency of the diodes to contribute unequally to total RF output, particularly in a varying temperature environment. The optional inclusion of RF lossy bypass capacitors to ground several points of the common node suppresses bias circuit oscillations.

Abstract: A large N.times.N Butler matrix is comprised of a first plurality of smaller essentially flat M.times.M Butler matrices arranged in a first stack and a second plurality of smaller, essentially flat P.times.P Butler matrices arranged in a second stack in which the planes of the matrices are orthogonal to the planes of the matrices of the first plurality. M can be equal to or differ from P.

Abstract: A mount and mechanism for imparting scan motion to a radar antenna useful in locations where obstructions forward of the antenna limit the field of view of the radar. The mount includes a carriage for translating the antenna transversely to the direction of beam propagation. Several mechanisms are disclosed for converting translatory motion to rotary motion and imparting the rotary motion as scanning motion to the antenna.

Abstract: An oxygen regulator for controlling the flow of breathing oxygen and uncontaminated air at various altitudes includes a balanced oxygen valve (20) and a balanced air valve (50) which cooperate with a dilution aneroid valve (62) to provide breathable mixture whose oxygen percentage increases with altitude to a predetermined altitude. Above that altitude one hundred percent oxygen is provided. A gas loading aneroid valve (110) operates to increase the oxygen pressure in accordance with altitude over a range of altitude.

Abstract: An A.C. motor is connected into a transistor bridge which includes a small current sensing resistor. The bridge is operated to supply alternating half cycles of current to the motor and resistor. The voltage drop across the resistor is compared in a comparator with a reference voltage which is equal to a fixed voltage minus a percentage of the bridge D.C. supply voltage. When the voltage drop across the resistor exceeds the reference voltage a gate means is closed to render the bridge transistors non-conductive.

Abstract: The elevation angle of a low angle target is accurately measured by subtracting from the received radar signal signals derived from an estimated value of target elevation which reduces the resulting signal to a minimum. The estimated value is an accurate measure of target elevation.

Abstract: A circular multimode antenna array having N radiating elements, an NXN Butler matrix and N-1 phase shifters includes feed networks comprising a back fill-in network, a sum pattern power divider network, a difference pattern power divider network and a sum-difference combiner network. The various networks are used either alone or in simultaneous combination to provide sum and difference circular antenna patterns having omnidirectional side lobes.

Abstract: A heat exchanger for cooling the recycled air of a self-contained closed loop breathing apparatus having a tank of high pressure breathable gas such as oxygen includes a heat sink located inside the tank, a heat exchange element located outside the tank in the stream of recycled air, and a heat pipe extending through one end closure of the tank providing heat communication between the heat exchanger element and said heat sink.

Abstract: A membrane interface is provided over the sample inlet port of an ion mobility detector. Sample, included as a vapor component in a gas stream impinging the exterior surface of the membrane, penetrates the membrane and is carried into the ion mobility detector by means of a carrier gas which scrubs the interior surface of the membrane.

Abstract: A plurality of binary pseudo noise generators are used to develop a Gaussian code that appears thermal noiselike in both amplitude and phase. Half of the pseudo noise generators are provided in an in-phase section and half in a quadrature section, with each said generator output being mixed with data to be transmitted and applied to modulate a carrier, the outputs from the various sections being combined for transmission. A receiver having the same number of pseudo noise generators and generating the same code synchronously demodulates the received data.

Abstract: A spirometer includes an expansible chamber of the piston type fitted with an indicia strip. The indicia comprise two columns of alternating light and dark bars. The columns are offset from one another by one-half the thickness of a bar and are respectively viewed by two photodetectors which generate signals which are shifted 90.degree. from one another as the columns pass through their respective fields of view. The signals are continuously sampled as digital words and consecutive words are compared to determine whether a counter should be incremented or decremented by one or two counts.

Abstract: A timing circuit (20, 22, 24) for use with a pulsed solid state radar generates signals which are applied to a pulse forming circuit (33) to provide preheat and immediately subsequent thereto current drive pulses applied to IMPATT diodes which in response thereto generate RF signal pulses (10, 12) having reduced chirp and level variations. The pulses are formed by transistors (70, 74) which are rendered conductive when their current return paths (28, 38) are established through resistors (34, 44) whose values determine the levels of the preheat and drive pulses.The duration of the preheat pulse is made responsive to ambient temperatures by using a negative-temperature-coefficient thermistor (86) as the time determining element of the timing circuit. The level of the preheat pulse is made responsive to ambient temperature by using positive-temperature-coefficient silicon thermistors (34) in the above mentioned current return path.

Abstract: A comparator has one input terminal connected to a reference voltage terminal and a second input terminal connected to sense the voltage on the resonator structure of a crystal filter. In the event the voltage on the resonator structure changes, such as by failure of the ground connection, the comparator generates an output signal indicating crystal filter failure.

Abstract: A pressure transducer is comprised of a crystalline quartz deflection plate which is clamped to a clamping plate having a rectangular hole therein so that deflection of the crystalline quartz plate in response to pressure difference thereacross is into the rectangular hole. The crystallographic axes of the deflection plate are arranged with respect to the longitudinal axis of the rectangular hole so that the deflection versus temperature curve of the transducer is a quadratic.

Abstract: First and second redundant command signals are formulated in parallel-by-bit digital format by two ganged wafer switch sets in a control unit. The first redundant command signal is stored in a shift register and subsequently strobed out, by clock pulses received from a remote unit, and transmitted to the remote unit in serial-by-bit format where it is stored and used to control the remote unit. The command signal is subsequently clocked out of the remote unit and returned to the control unit in serial-by-bit format where it is compared against the second redundant command signal to insure that the remote unit has responded to the proper command.A renewable timer is reset by the clock pulses. If the clock pulses are interrupted for more than a predetermined time the renewable timer times out and indicates a fault.

Abstract: This invention comprises means for monitoring the operation of an aircraft landing guidance system which functions independently of the landing guidance system. The means include a radio altimeter aboard the aircraft, a reflector positioned on the ground at a predetermined location along the prescribed approach path to provide enhanced return of the altimeter signal and means for comparing the actual radio altitude with a predetermined altitude value to provide an indication of the location of the aircraft within a tolerable distance from a prescribed point on the approach path.

Abstract: A radar field of interest is divided into cells at a common range but at different angular spacings. The second derivative of the signal intensity of a radar return signal in each range cell is obtained by subtracting the signal intensity in the cell of interest from the signal intensity in the adjacent cell to obtain the first derivative and then subtracting the first derivative thus obtained from the subsequent first derivative. The second derivative is summed with subsequent second derivatives and further summed with the original return signal. The last sum is scaled, raised to an exponential value and again summed with the original return signal. The resultant signals from each range cell are reassembled to form a field of data corresponding to the radar field of interest.

Abstract: Digital codes, each of which is comprised of a series of equally spaced pulse positions bracketed by framing pulses are passed through a delay line having a plurality of taps. The taps are connected in a gating structure which extracts only valid codes and suppresses garbled and phantom codes.

Abstract: A capacitance-type fluid gage has the probe electrode shaped in accordance with a specified function of container volume and the relative dielectric of the fluid to be gaged.

Abstract: An aircraft air speed signal is differentiated to provide a signal related to rate of change of air speed. This signal is added to a signal related to aircraft barometric altitude change with the sum signal being compared against aircraft radio altitude to generate warning if the aircraft rate of descent is excessive for the conditions encountered.