Abstract: In accordance with the principles of the invention, a surveillance radar is provided with a rotating, frequency squinting, end-fed slotted array antenna, which is caused to transmit a plurality of different carrier frequency pulses for successively illuminating specific antenna beam positions during rotation of the antenna. Upon reception of each radar signal return, a signal processor responsive to the frequency of each transmitted pulse and the mechanical pointing angle of the antenna at the time of transmission of each pulse, will determine the frequency dependent squint angle for the transmitted pulse and combine that angle with the instantaneous mechanical pointing angle of the antenna at the time of the pulse transmission, to determine the actual beam pointing angle for each pulse at the time of its transmission. A video signal processor groups together the pulse signal returns from physically adjacent ones of the actual beam pointing angles for common processing, i.

Abstract: A communication system for receiving aircraft reply squits (transmissions) normally used in a radar beacon system for surveilling aircraft in a given geographic area. The communication system includes a plurality of omnidirectional receivers, each receiver having a function of omnidirectionally receiving the aircraft squits and developing therefrom two types of information strings, namely a data string, indicative of a message in the aircraft squit, and a corresponding confidence string indicative of the reliability of the developed data string. A data communication link transmits the data and confidence strings between the plurality of omnidirectional receivers and the master data processor.

Abstract: System for tracking a vehicle equipped with a transponder which emits a first reply signal containing data identifying the vehicle in response to a first interrogation signal and emits a second reply signal containing data specifying the altitude of the vehicle in response to a second interrogation signal, the system including: (a) a squitter transmitter located on the vehicle for interrogating the transponder with the first and the second interrogation signals which are separated in time by a predetermined time spacing interval, in response to which first and second interrogation signals, the transponder transmits the first and second reply signals; (b) a plurality of spaced apart ground receive stations, each of which includes a receiver and decoder for: (i) receiving and decoding data from the first and second reply signals, (ii) determining a time of arrival of the first and second reply signals and the predetermined time spacing interval, and (iii) determining an identity of the vehicle by combining data

Abstract: A system for locating and identifying aircraft while on an airport. Each aircraft has an IFF transponder which is interrogated from on board the aircraft to produce replies at a slower rate than normal interrogation rates. A plurality of receiving stations at different locations about the airport measure the time of arrival of the replies and decode the replies. The time of arrival information is forwarded to a central receiving station along with the decode reply data. Using conventional correlation techniques, the location of each aircraft is established through the time of arrival information as well as the identity of the aircraft from the decoded reply data.

Abstract: Tracking system for monitoring aircraft position during simulated training exercises. Standard IFF transponders on the aircraft are periodically enabled by a squitter transmitter mounted on the aircraft. On the ground a plurality of receiving stations are interconnected through a communication link. The transponder replies are received at each receiving station. The time of arrival for each of the transponder replies is measured and communicated to one of the receiving stations. Using Loran techniques, accurate longitudinal and latitude coordinates are determined from the time of arrival data.

Abstract: An alarm signalling method and system utilizing cross cueing between radio, audio and visible alarm signals which are emitted by an alarm signalling unit. A method and system for measuring the range between the alarm signalling unit and a receiver carried by a rescuer wherein the differences in the time of receipt at the receiver of simultaneously emitted radio and audio signals is used as a measure of range.

Abstract: An aircraft locating system identifies on a TV format radar display the position of a specific aircraft based on an RF transmission from the aircraft on an RF channel. The locating system includes at least a pair of receive stations located within several miles of an airport and separated by a base line which is in near proximity to at least one runway at the airport or a theoretical extension thereof. Each receive station includes a passive receiver for determining a bearing angle to a source of RF on the RF channel for generating a signal representative of the bearing angle.The locating system further includes a processor which is responsive to bearing angle signals derived from the receive stations for generating line count and line delay information. The line count and line delay information correlate a position determined by the bearing angle signals from at least a pair of receive stations with a frame of reference of the TV display.

Abstract: Unattended measurements of horizontal and vertical visibility are broadcast, along with the results of time trend analysis so as to provide for short-term prediction of visibility. A calibration mechanism is provided along with sensors to determine mis-alignment of the apparatus. Broadcast information is particularly useful to pilots approaching unattended airports for landing.

Abstract: The invention provides an apparatus for processing radar returned video signals in the vicinity of an airport including at least one runway and at least one vehicle roadway intersecting the runway, in order to assist air traffic controllers in detecting potential hazardous situations. Radar returns from each of plural geographic monitored locations are compared with a simulated return for each corresponding location to detect a moving object at any of said geographic monitored locations. The presence of a moving object at one of such locations may be indicative of a hazardous situation, and in that event, the air traffic control operator may be warned by an alarm or the like.

Abstract: A method and apparatus for determining the dew point or dew point depression which is arranged for unattended operation and is extremely accurate in the vicinity of very small dew point depressions. In addition to measuring present dew point depression, historical records are maintained and the device is arranged to perform a time trend analysis so as to provide for short term future prediction. Output is provided via a voice synthesizer and a radio. Dew point depression is computed by determining the adiabatic change in volume required to produce condensation. The change in volume is produced by rapidly expanding a test chamber. The measurement cycle concludes with a compression step to raise chamber temperature to at least freezing.

Abstract: Apparatus for recording and play back of radar video employs a conventional TV video recorder. A multiplexer accepts radar timing signals, synchro data definitive of azimuth, a 60 Hz. reference as well as radar video and formats the signals for recording. A demultiplexer accepts video signals formatted as above, from the conventional video recorder and reformats the signals to drive a conventional PPI display. The video recorder is unmodified so conventional TV video can also be recorded or played back, interspersed, if desired, with the radar video.

Abstract: An antenna array suitable for mounting at a selected height above a target plane, which provides for excellent resolution along a line in said plane extending through the vertical projection of the center of said array and perpendicular to a plane including said array. The array may comprise a plurality of radiators, each having a phase center along a support. The support is constrained to describe a segment of a circle in a vertical plane whose center lies on said line. As a result, the distance from any arbitrary point on the line in the target plane to any element of the array is equal.

Abstract: The present invention relates to an improved goniometer circuit having extremely low modulation harmonic distortion characteristics, which is particularly suitable for use in a VOR navigation system. In the disclosed circuit, modulation harmonic distortion is greatly reduced by the use of a phase lock loop operating at small signal levels prior to the power amplification stage of the system. The phase lock loop employs a voltage controlled oscillator to completely eliminate harmonic distortion so that the final output of the system is virtually modulation free.

Abstract: A display indicia generator driven by compressed data is arranged to draw indicia on a display coordinated with signals from an external environment. For drawing a line, for example, the compressed data includes coordinates of a point on the line, a slope of the line and a length of the line. The display includes a deflection system for deflecting a writing beam, such as a cathode ray beam, over the display area in a predetermined pattern, i.e., a raster scan or PPI display. The signal source for the external signals to be displayed is coupled via a mixer to the unblanking control of the display. Another input to the mixer comes from the indicia generator which is arranged to enable the beam when it reaches a point, such as the start point on the line. On each succeeding coordinate scan, counters keep track of the portion of the sweep during which the beam should be unblanked so as to display the line. At the completion of the frame, the indicia has been generated concurrently with the signals.

Abstract: A radar with 3-D capability comprises a conventional 2-D radar with a height finding attachment. More particularly, a height finding antenna is mounted on the back surface of the conventional 2-D antenna reflector and points in a direction 180.degree. offset in azimuth from the direction of the 2-D antenna. An r-f transmitter with a linear frequency modulated output is coupled to the height finding antenna and controlled by a transmit control based on target range and azimuth data provided by the 2-D radar. The height finding pulse compression receiver also responds to this target information as well as the height finding return radar signal and extracts height information which is then made available to a suitable display.