Abstract: LORAN-C navigation equipment is disclosed wherein digital circuitry is used to automatically distinguish a master LORAN-C transmitting station from a secondary station. The equipment operator manually enters approximate time difference of signal arrival information for a particular secondary station into the equipment after consulting a LORAN-C chart. The operator then manually determines the exact time difference of arrival using thumbwheel switches and a LED lamp display. This procedure is repeated to determine exact time difference of arrival information for the master and each selected secondary station, and the information is plotted in a well-known manner on the LORAN-C chart to locate the position of the craft upon which the equipment is located. Manual acqisition of secondary stations simplifies the equipment and eliminates interference problems caused by skywaves and other transmissions.

Abstract: A cooperative type aircraft anti-collision radio system utilizes radio transmitters and receivers transmitting and receiving on a single radio frequency common to most aircraft having radio systems or on multiple radio frequencies if desired. Each aircraft will be capable of transmitting at least one and preferably a plurality of selected tones which may be received by appropriate radio receiver circuitry of other aircraft operating in the vicinity. Conventional automatic direction finding circuitry ascertains the bearing of the aircraft transmitting a modulated tone or tones which is displayed for visual inspection. By interpreting changes in the bearing of the aircraft transmitting the tone or tones and/or by interpreting the strength of the signals being received a decision may be made whether or not evasive action is required in order to avoid a collision.

Abstract: In a doppler radionavigation system wherein a transmitted signal has opposite frequency coding during alternating time intervals, a reference antenna is provided which has different radiation modes during the alternating time intervals. In a preferred embodiment, the two reference antenna modes have substantially the same amplitude radiation pattern, but different phase radiation characteristics. The phase between the radiation in a selected direction and the radiation in the remaining directions is different for the two antenna modes. This phase change substantially reduces the position determination error resulting from multipath signals.

Abstract: The frequency scanned corner reflector antenna is a modified corner refler antenna that incorporates a feeding technique to achieve monopulse or sequential lobing radiation patterns in one principal plane and one or more frequency-scanned beams in the other principal plane. Scanning of the beam of the corner reflector antenna for direction finding and tracking applications is accomplished without destroying the unique monopulse and sequential lobing capabilities of the antenna.

Abstract: An instantaneous, omnidirectional direction finding system for locating an incoming wave over a complete 360.degree. arc in space employing a circular antenna array and a fixed phase shifting network for deriving from said array a differently time phase shifted signal for each different spatial direction. The array observes all spatial directions continuously, as opposed to a sequential angular scanning technique. In a preferred system, the phase shifting network provides a plurality of output modes wherein the incoming wave is defined by different phase displaced signals that are compared and quantized to obtain a digital code representing direction.

Abstract: An air navigation and landing aid system wherein a pair of transponder beacons are located at known positions adjacent an airport runway. The aircraft carries a weather pulse radar system and an antenna for furnishing information affording a navigation aid during the flight stage. Switching means are inserted between the antenna and the weather radar for switching, during the landing stage, the received pulses relating to each beacon, in response to the interrogation of the weather radar, to a special receiver and a processing circuit which furnishes information affording a landing aid.

Abstract: A broadband localizer antenna array with an even number of elements is supplied by a backmatched power dividing network comprising two chains of directional couplers and a group of hybrids which divide the power among the elements in accordance with geometrical progessions. The center elements in the array may be spaced 0.6 wavelength apart at the average frequency. Other spacings between the elements are greater than 0.6 wavelength.

Abstract: A radio beacon for a nautical emergency rescue system includes a flotation housing containing an antenna in an upper portion, a ground plane and a transmitter in a central portion, and batteries in a lower portion. When placed in the water, the lower section is submerged and the central section is at surface level, enabling contact between the ground plane and the water via conductors that pass through the housing. The upper portion projects above the water to permit efficient radiation from the antenna, which consists of a vertical rod and a coaxial cylindrical can that is open at the bottom end. The upper end of the rod is attached to the center of the can closed end. The radio transmitter is frequency modulated in a distinctive pattern, and operates with a duty cycle that permits detection and direction finding of multiple such beacons.

Abstract: An aircraft landing system which provides a pilot a perspective view of a nway on which he intends to land under zero visibility conditions. The system includes a multiplicity of microwave transmitters spaced at known intervals along both sides of a runway and a timing generator which causes the microwave transmitters to transmit in sequence. The aircraft contains a monopulse receiver which provides conventional azimuth angle video information to a CRT display and also provides range video information to a Y sweep generator. The latter Y sweep generator generates a sweep voltage for the Y axis of the CRT display which is of sufficient length to display all transmitted pulses from all microwave transmitters in sequence with the correct relative spacing between microwave transmitters.

Abstract: A beacon receiver or IFF system in which the gain of the receiver is time varied to enhance the discrimination between response from transponders located ahead of the interrogator as compared with the responses from transponders in the side or rear lobe regions of the interrogator antenna pattern. The system is employed with a directional antenna and signal processing apparatus giving sum .SIGMA. and difference .DELTA. channels. In accordance with this invention, the gain of the receiver in the sum .SIGMA. channel is increased from the minimum value to a maximum value beginning after the end of interrogation pulse. The difference .DELTA. channel is varied in gain from the time in the beginning after the end of the interrogator pulse but the gain is varied inversely from the maximum level at the beginning of reception to a maximum level at the end of reception.

Abstract: Flat radar antenna for radar apparatus comprising a plurality of aligned radiating elements disposed in parallel rows, in which the quantity of energy flowing between each one of said elements and the radar apparatus can be adjusted, characterized in that said radiating elements are waveguides with coplanar radiating faces, said waveguides being grouped according to four quadrants, each one of said quadrants being connected with the radar apparatus by means of a feed device adapted to take on one of two conditios, one in which it feeds all the waveguides in the quadrant and the other in which it feeds only the rows nearest to the center of the antenna excluding the other waveguides in the quadrant, means being provided for the four feed devices to take on at the same time the same condition, so that the radar antenna emits a radar beam which is symmetrical relatively to the center of the antenna, and having a different configuration according to the condition of the feed devices.

Abstract: A thermoelectric voltage generator utilizing heat from a vehicle exhaust to rovide a differential temperature through a plurality of thermoelectric elements comprised of serially connected alternate N- and P-type semiconductors having alternate electrical contacts between adjacent elements at a hot side and at a cold side to produce electrical energy in accordance with the Seebeck effect and in which the electrical energy is applied to an external device by way of connections at opposite ends of said plurality of thermoelectric elements.

Abstract: A decision circuit for use in pulse doppler proximity fuzes having three er-connected time-gated detection channels. The logical pattern of combining the outputs of these detection channels allows a pulse doppler fuze to operate more effectively in an ECM and clutter environment.

Abstract: A target indicating system includes a high-range-resolution monopulse radar hich produces four dimensions of data: a range trigger signal, elevation angle error data, azimuth angle error data, and range video data. Additionally included is a display system having an x-y display for presenting the four dimensions of data. The display is improved by the addition of a sweep generator, elevation summary amplifier, and azimuth summing amplifier which cause the trace on the display to be driven diagonally and generate an isometric presentation of the four dimensions of data.

Abstract: A digital communication system for the transmission of digital data with a modulated carrier uses a modulation locked loop and pseudo-random code to develop synchronization signals for the digital data signals and to ensure a high level of communication reliability.

Abstract: A photoconductor-switched electroluminescent matrix panel for use in a laser-addressed tactical data display system in which photoconductor elements on the back of a screen are connected in series with electroluminescent display and feedback elements which form the front of the screen and an a-c power supply. The photoconductor has a high dark impedance so that in the initial OFF position insufficient a-c power passes through the electroluminescent elements to cause significant light emission. When the photoconductor is illuminated with a light pulse from a scanning laser beam, the impedance drops sharply so that substantially all of the a-c supply voltage is received by the electroluminescent element thereby causing the element to luminesce. The photoconductivity persists long enough for the electroluminescent emission to build up and sustain the low photoconductor impedance via optical feedback.

Abstract: A guidance system for aircraft and ships, which system comprises at least two localizer antenna arrangements which are spaced in elevation above a reflecting surface, at least two distance measuring antenna arrangements which are spaced in elevation above the reflecting surface, and at least two glide slope antenna arrangements which are mounted vertically above each other, the guidance system being such that the localizer antenna arrangements are at a mean height of at least 21/2 wavelengths above the reflecting surface and are fed with signals having the same radio frequency but having a phase difference, the distance measuring antenna arrangements are at a mean height of at least 25 wavelengths above the reflecting surface and are fed with signals having the same radio frequency but having a phase difference, and the glide slope antenna arrangements are fed with signals having the same radio frequency but two different frequencies of amplitude modulation to give by reflection from the reflecting surface at

Abstract: An improved thermopile construction particularly adapted for use as an electric generator for producing a signalin response to heat from a pilot flame. Groups of elongated elements of dissimilar metals are assembled or arrayed in a circle within a metal sleeve to produce a pilot generator. The first group of elements is arrayed against the inside wall of the metal sleeve and the second group of elements is assembled radially inwardly from the first group. Respective ends of the elements of the first group and the second group are joined with the opposite end of the respective end of the element of the second group being joined to the opposite end of the next adjacent element of the first group. Individual elements of each group have a cross-sectional configuration to provide for optimum heat transfer between the sleeve and elements of the first group and to provide for assembly of the elements of the second group in a circle of smaller diameter.

Abstract: A step track antenna system adapted for tracking rapidly moving signal sources, in which systematic step commands cause antenna rotation in fixed angular increments about each of two orthogonal axes so as to maximize the strength of the received signal. In each axis, the direction, or polarity, of each step is selected in response to a comparison of the signal strength existing before and after the last step that was taken about that axis. A determination is made from this comparison as to which direction a step must be taken in, to produce an increase in signal strength. The step tracking rate is augmented by generating a signal representative of the time integral of the polarity indications. The antenna servo system responds to this signal by imparting a corresponding, continuous rate of motion to the antenna. The effect of this rate augmentation is to reduce the amount of antenna motion which must be accounted for by the step tracking process.

Abstract: A radio frequency beam forming network is disclosed wherein a plurality of antenna feed elements arranged in the focal plane of a radio frequency lens is coupled to corresponding input ports of a radio frequency energy distributing means. Output ports of such radio frequency energy distributing means are coupled to a receiver/transmitter through different paths. Disposed in the different paths are active elements, including variable phase shifters and attenuators. The active elements, in response to control signals, provide proper attenuation and phase shift to the signals passing therethrough thereby to form a desired antenna beam. Such antenna beam is comprised of one or more "spot" beams. With such arrangements failure of a single one of the active elements will only slightly degrade system performance without resulting in a complete loss of any one of the "spot" beams.