Abstract: A method and a system for determining an altitude of an object of interest, for example, an airplane that transmits electromagnetic radiation in the form of radar signals. A number of sub-units that can detect the radar signals are spread out in an area, preferably in a large geographical area, where the radar signals of the airplane/object it is possible to detect. The sub-units communicate to the information center when they are able to detect the radar signals. The information center determines the altitude of the airplane based on the airplanes line of sight, i.e., its radar horizon, and thus which sub-units can detect the radar signals.

Abstract: A vehicle position determination system for determining the position of a moving vehicle having a transponder includes a first and second antennas operable to receive periodic radio frequency data signals from the transponder when the transponder is moving through a first or second predetermined coverage zone, respectively. The first and second coverage zones partially overlap and each have a width that is orthogonal to the travel path of the moving vehicle and a length that is parallel to the travel path of the moving vehicle. A processor counts the number of periodic data signals received by each of the antennas from the transponder during a time period and determines based on the count a probable location of the vehicle. The vehicle location information can be provided to an imaging system to discriminate between transponder and non-transponder equipped vehicles.

Abstract: An improved traffic alert and collision avoidance method and device wherein TCAS data is augmented by higher resolution radar data. By using radar to search out targets, altitude information can be developed for those aircraft not equipped with altitude reporting transponders. The improved accuracy also allows angle/angle perspective display of air traffic and thus provides enhanced situational awareness.

Abstract: The present invention provides a radio navigation emulating GPS device. In one embodiment, the radio navigation emulating GPS device receives an identifier associated with a conventional radio navaid. The present radio navigation emulating GPS device then retrieves latitude and longitude information corresponding to the received conventional radio navaid from a database. A satellite based position information system generates position information for the aircraft on which the present radio navigation emulating GPS device is disposed. The present radio navigation emulating GPS device then generates navigation information for the aircraft using the retrieved latitude and longitude information and the satellite based position information for the aircraft. The present radio navigation emulating GPS device then presents the navigation information in a manner which emulates the presentation of navigation information generated by a conventional radio navigation device.

Abstract: A device and method that allows a pilot to switch between communication and navigation inputs without disrupting the pilot's current task. An audio selector panel has inputs for at least two communication transceivers and outputs for at least a pilot's headset. A rotary switch on the face of the audio selector panel selects which inputs are connected to which outputs. The audio selector panel further includes a remote swap switch that is mounted in a position in which the pilot can activate the switch without removing his/her hands from a yoke or diverting his/her eyes to the switch. The activation of the remote swap switch causes the audio selector panel to switch between the communication and navigation inputs. In this way, the pilot can switch communication and navigation inputs without disrupting the current task of the pilot.

Abstract: An object detecting system mounted on a conveyance such as a vehicle having a laser radar as an object detector mounted on the vehicle at a position offset from the vehicle longitudinal center line, for adjusting in a factory the radar mounting position in a software manner by utilizing a computer program. A reflective target is placed ahead of the vehicle on the line extending from the vehicle longitudinal center line at a position relatively close to the vehicle in the factory. The central axis of the transmitted beam is first aimed at the target reflector such that the axis is made equal to the direction of the target reflector, and is changed by an angle of offset such that the axis is aligned with an inherently desired direction which is parallel to the vehicle longitudinal center line.

Abstract: A method for acquiring map information, a method of navigation, a method for providing area information, a navigation apparatus and an area information providing apparatus in which a predetermined broadcasting signal transmitted from a transmitting station, which is different at every area, is received by a receiver where map information at every area, which is included in the received broadcasting signal, is extracted by a map information extractor unit, and the map of an area, to which a present position belongs, is displayed on a display unit based on the extracted map information.

Abstract: A golf distance indicator system provides measurement and display of the distance between a golfer and the pin on the green he is approaching. The system comprises a portable unit carried by the golfer and an target unit located on the pin. With the portable unit, the golfer selects the hole he is playing then activates the system. The portable unit sends a wireless coded message to an intended target unit. When a target unit receives a message, it analyzes the message to see if it should respond. If the target unit determines that it should respond, it sends a coded responding message to the portable unit. When the portable unit receives a responding message, it analyzes the responding message to see if the responding message originates from the intended target unit. If it does, the portable unit calculates a distance based on the elapsed time for the communications and the speed of the communications. The results are displayed on the portable unit.

Abstract: An apparatus and techniques for correlating crossing targets in an air traffic control system is described. The technique utilizes a target/track correlation made on the basis of three conditions: (1) separation distance between a target pair; (2) target polarity and (3) a value of a threshold separation value indicator.

Abstract: A non-linear junction detector designed for counter surveillance measures achieves superior performance by using a single circularly polarized antenna to transmit a signal and to receive harmonics of the transmitted signal that are re-radiated by a non-linear junction such as would be found in a eavesdropping device containing a semiconductor. The antenna is mounted on a telescoping antenna extension assembly. A single electrically conductive cable is contained inside the antenna and connects the antenna to the transceiver case which houses the non-linear junction detector electronics. A cable winder is built into the antenna and is employed to provide automatic dispensing and retraction of the cable when the antenna extension assembly is extended or retracted. A display is built into the antenna head assembly to provide signal strength indications and operational information concerning the functioning of the non-linear junction detector to the user of the device.

Abstract: A method and apparatus are disclosed for making precise velocity measurements of a spacecraft using a two-way noncoherent Doppler tracking system. The received uplink and transmitted downlink frequencies on-board the spacecraft are compared with the resulting information being included in the downlink signal and used to cancel spacecraft oscillator drift rate effects in the two-way Doppler measurement made by the ground station. The information can also be used to characterize the drift rate of the spacecraft oscillator, thus permitting periods of accurate one-way Doppler tracking by the ground station. To improve accuracy, the times at which the measurements comprising the information would have been observed on the ground are inferred from the measurement of a signal generated by the spacecraft, e.g., the telemetry frame start times, made by the ground station.

Abstract: A system is described for discriminating between a transmitted signal and background noise comprising a transmitter adapted to transmit a signal including first and second pulses, separated by a predetermined time interval; and a receiver including a pulse detector to detect pulses received from the transmitter; a delay circuit adapted to delay transmission of the first pulse for a predetermined period of time in communication with the detector to receive a pulse therefrom; and an AND gate having an output, a first input in communication with the delay circuit and an second input in communication with the detector, the time of transmission between the pulses equaling the time delay of the delay circuit, whereby the AND gate allows transmission of a signal only when simultaneously receiving pulses from the detector and the delay circuit.

Abstract: A vehicle control system and method which can realize automatic driving of a vehicle under control of a base station with a high accuracy of the order of cm, low costs and a high reliability. On the basis of information relating to positions or speeds of other vehicles or fixed vehicles obtained through communication units installed in the vehicles and base station, the system know presence of vehicles in proximity to each vehicle, proximity distances, proximity directions or relative speeds thereof, informs an associated driver of it, or controls movement states of the proximity vehicles to avoid any contact with the proximity vehicles on the basis of the proximity information.

Abstract: A secondary surveillance radar e.g. a Mode-S radar, has a controllable power source in which first and second in-phase r.f. signals are derived from a source (6) by a power splitter (11), and a phase shifter (32) adjusts selectively the relative phase of the signals, so that after amplification by main amplifiers (21, 22) and combination by power comber (23), the resultant power level can be controlled by the phase shift produced by the phase shifter (32).

Abstract: A device and method that allows a pilot to switch between communication and navigation inputs without disrupting the pilot's current task. An audio selector panel has inputs for at least two communication transceivers and outputs for at least a pilot's headset. A rotary switch on the face of the audio selector panel selects which inputs are connected to which outputs. The audio selector panel further includes a remote swap switch that is mounted in a position in which the pilot can activate the switch without removing his/her hands from a yoke or diverting his/her eyes to the switch. The activation of the remote swap switch causes the audio selector panel to switch between the communication and navigation inputs. In this way, the pilot can switch communication and navigation inputs without disrupting the current task of the pilot.

Abstract: A long range identification system is disclosed for utilizing a radio frequency (RF) signal sent by a calling location, such as a mass transit vehicle, as the energy source to power response apparatus at a responding location, such as a route stop of the transit vehicle. The responding signal is then broadcast within the transit vehicle as audio or as a video display of a signal from a character generator, or as both audio and video.

Abstract: A system and apparatus for enhancing the satellite based navigation systems which includes providing an aircraft with an interrogating radar for interrogating beacons disposed at a predetermined location in front of a runway wherein the beacons are radar-activated passively powered runway beacons.

Abstract: A method and apparatus are disclosed for making precise velocity measurements of a spacecraft using a two-way noncoherent Doppler tracking system. By comparing the received uplink and transmitted downlink frequencies on-board the spacecraft, information is generated that is included in the downlink signal and used to cancel spacecraft oscillator drift rate effects in the two-way Doppler measurement made by the ground station. This data can also be used to characterize the drift rate of the spacecraft oscillator, thus permitting periods of accurate one-way Doppler tracking by the ground station.

Abstract: A method of determining the exact location of a transponder with respect to a reader antenna, with no additional components to the existing system required, is disclosed. An existing pin of the reader IC, the RSTP pin, provides an analog fieldstrength signal from which the distance to the reader antenna is deduced via known in the art signal processing methods. A grid or even an exact position location along a route is also achievable with initial set-up of at least two transponders a predetermined distance apart and a reader antenna.

Abstract: A communication system is provided for identifying the position of aircraft in a surveillance area. The communication system includes a dual-frequency interrogator which produces two signals at different frequencies. These signals are transmitted over a narrow beam, scanning antenna, the antenna being located within the surveillance area. A transponder is provided on the aircraft with an auxiliary antenna assembly tuned to a frequency equivalent to the difference between the dual frequencies. The transponder produces a signal containing aircraft identification information. A processing unit is co-located on the aircraft with the transponder to receive the two signals transmitted by the interrogator and produce a signal equivalent to the difference between those signals. The difference signal produced by the processing unit is coupled with the transponder and is used to identify the position of aircraft on the ground.

Abstract: Apparatus for associating target reply signals with target signatures, wherein each reply signal is received from a target transponder within a selectable time period, and further wherein each target signature comprises a first set of parameter values that identify a target position and movement relative to an interrogating aircraft, the apparatus including reply processor means for producing a target report for each reply signal, the target report having a second set of parameter values; and report processing means for: 1) comparing each target report with each target signature to identify which report/signature pairs are potential matches, each comparison between a target report and a target signature being based on comparisons of corresponding parameter values to produce a probability of match for each parameter comparison; and 2) identifying which report/signature matches are best based on comparison of each report/signature potential match with each other potential report/signature potential match includ

Abstract: Apparatus for rejecting multipath reply signals received from a target transponder within a selectable time period, comprising: a top antenna and a bottom antenna to detect reply signals; means for determining an altitude code associated with each reply signal detected by the antennas respectively; means for determining a differential time of arrival (DTA) value for each reply signal detected by the antennas respectively; and processing means for: 1) producing, for each top antenna reply signal, a top antenna target report that includes the altitude code and DTA values; 2) producing for each bottom antenna reply signal, a bottom antenna target report that includes the altitude code and DTA data; and 3) comparing each top antenna report data with corresponding data from each bottom antenna report, and marking out each bottom antenna report that is a multipath reply based on such comparison.

Abstract: Disclosed are a device for the detection of S mode responses received by a secondary radar receiver and its use for the filtering of the pulses contained in this response. The device furthermore comprises means to detect a signal S, means for the real-time computation of the mean values of magnitudes characterizing the pulses that belong to the response, and means for the filtration, by comparison, of the values of the magnitudes measured on each pulse detected with the mean value of the corresponding magnitude.

Abstract: An airborne radio system upon receipt of mode and code radio signals from a arker beacon that it is seeking, queries the marker beacon as to its slant range and direction. Upon receipt of information on the slant range and direction the airborne system and/or its operator make a determination whether to initiate a radio signal that would activate a flare on the marker beacon. Upon actuation the flare is usable for visual and infrared homing.

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 navigation system for a vehicle travelling along a highway that has an interrogator mounted on the vehicle and, a retrodirective transponder mounted alongside the highway for updating vehicle location. For collision avoidance systems, interrogators transmit and receive fore and aft, and transponders are mounted to respond to signals fore and aft of the vehicle. The transponder modulates information onto the interrogation signal, and retransmits the encoded interrogation signal back in the direction of arrival of the collected interrogation signal. The responder uses a Van Atta array antenna and is capable of responding to an interrogator signal incident over a wide solid angle of arrival while retrodirectively retransmitting without amplification substantially all of the collected signal within a narrow solid angle. The responder may be implemented using monolithic microwave integrated circuit technology (MMIC), thus being suitable for high volume production.

Abstract: Methods and apparatus for detecting and decoding transponder reply signals of the type having a plurality of associated time discrete pulses including two bracket pulses and a number of related data pulses that may have been transmitted at discrete data time intervals between the bracket pulses such that the signal content detected during the data time intervals corresponds to the reply signal data code, comprising receiver means for receiving the reply signals and producing in-phase (I), quadrature (Q) phase and video (V) signals for each received pulse; means for detecting received pulses and storing the I/Q/V signals in a first memory; means for storing in a second memory pointer values that correspond to the temporal location of pulse I/Q/V signals in the first memory; means for identifying, based on time of arrival (TOA) values, pairs of potential bracket pulses wherein each pair marks the beginning and end of a reply code; and processor means for 1) determining an angle of arrival (AOA) value for each d

Abstract: A method and means for evaluating transponder reply signals in a secondary radar system to differentiate valid replies from false replies. Transponder reply signals received by the interrogating radar are decoded to establish conformity with an established format. All decoded replies to a succession of N interrogation signals are stored in their order of reception in an array of N shift registers. A reply filter is associated with each of the N shift registers. The reply filters operate in parallel to scan the stages of each associated shift register. A unary adder provides the number M of replies detected by the reply filters at each scan step. Reply decision means selects a threshold value that is dependent upon operating conditions of the radar and generates a valid reply signal whenever the value M equals or exceeds the selected threshold value.

Abstract: A transponder system comprising an interrogating source of HF electromagnetic radiation, and a plurality of transponders which each include a token reader unit to receive a removable token, e.g., a smart card, including onboard data processing capability. The transponders, or a group of transponders, are each arranged when interrogated to transmit a unique HF response modulated by information taken upon the token.

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: A secondary surveillance radar system combines a mechanical scanning type of mode-S sensor using a mechanical rotation type of antenna and an electronic scanning type of mode-S sensor using an electronic scanning type of antenna. The mechanical scanning type of mode-S sensor performs at least mode-A/C general inquiry/response with aircraft targets and create a file of surveillance data obtained by the general inquiry/response. This allows circumvention of problems, which would be encountered in performing the same processing by using the electronic scanning system, such as the deterioration of accuracy of monopulse angular measurement, the increasing probability that unwanted responses will be received, etc., which are due to the elevation dependence of horizontal beamwidths.

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: A circuit for filtering pulse sequences of a given frequency out of a composite signal includes a series combination of a monostable multivibrator (MF) and a random-access memory (RAM), an address register and a clock. The monostable multivibrator (MF) serves as a pulse shaper of incoming signals. The input (D.sub.E) and output (D.sub.A) of the random-access memory (RAM) are connected to the inputs of an AND gate (UG). An address counter register (AR) associated with the random-access memory (RAM) has a count cycle whose duration is equal to the pulse spacing of the sequence to be recognized. During each clock period (T2), the current signal state of the input (D.sub.E) of the random-access memory (RAM) and the content of the addressed memory cell are checked for equality by the AND gate (UG) and the current signal state is then written into the cell.

Abstract: The present invention is directed to a Mode S uplink or interrogation signal demodulation system which can quickly recognize the Mode S signal and also filter out of noise present in the Mode S uplink or interrogation signal, thereby reducing the bit error rate. To realize this goal the present invention includes a digital differential phase-shift keyed demodulator to demodulate the differential phase-shift keyed data, thereby reducing the time needed to acquire the Mode S uplink or interrogation signal. This digital demodulator also reduces the noise present in the Mode S uplink or interrogation signal and provides an integrated system which is small in structure that can be easily implemented in an aircraft. This Mode S system also includes a preamble and sync phase reversal detection circuit to recognize if the transmitted signal is a Mode S signal. This signal also utilizes Mode A and Mode C detection devices to make the system compatible with present communication systems.

Abstract: An airborne surveillance method and system allows an observer aircraft to determine the position and change of position of a multiplicity of target aircraft and thus allows analysis of collision threats from these aircraft. The system uses a phase comparison direction finding antenna to determine direction of nearby ground based SSRs and all target aircraft of interest. The system further makes use of all other available data including Mode C transponder generated altitude information of the target aircraft, the altitude of the observer aircraft, the received signal strength of both the SSR beam and the received transponder signal, the time difference of arrival between the SSR interrogation signal and the response from the target aircraft, and a variety of other factors to determine the position of the target aircraft.

Abstract: An airborne surveillance method and system allows an observer aircraft to determine the position and change of position of a multiplicity of target aircraft and thus allows analysis of collision threats from these aircraft. The system uses a phase comparison direction finding antenna to determine direction of nearby ground based SSRs and all target aircraft of interest. The system further makes use of all other available data including Mode C transponder generated altitude information of the target aircraft, the altitude of the observer aircraft, the received signal strength of both the SSR beam and the received transponder signal, the time difference of arrival between the SSR interrogation signal and the response from the target aircraft, and a variety of other factors to determine the position of the target aircraft.

Abstract: A radar transponder comprising:a control circuit for controlling transmission and reception of signals in order to receive a receiving signal and transmit a definite answer signal,a video amplifier for amplifying the detection signal of the receiving signal, andan auxiliary video amplifier for amplifying the amplified output signal up to the level allowing the control circuit to be triggered,the radar transponder providinga video switch between the amplifier and auxiliary amplifier and switched in such a manner that a signal input to the auxiliary amplifier is broken only during the transmitting period of the answer signal by feeding back a positive potential pulse synchronized with the output signal from the control circuit and an input signal applied to the auxiliary amplifier is conducted except during the transmitting period of the answer signal, thereby delivering an output signal of the video amplifer to the auxiliary amplifier, andfurther, on respect, a pulse stretcher circuit between the control circu

Abstract: Transponder reply rate limiting employing a circular memory queue to store the times of prior responses up to the limits of circular memory queue capacity. Separate circular memory queues contain the times of (1) long replies, and both (2) long or short replies. Each circular memory queue has a pointer and several offset indicators which are spaced from the pointer to the time entry positions at predetermined intervals according to corresponding preestablished criteria. After each transponder reply, the time of the reply is entered in the circular memory queue at a next pointer location. Eartimes, i.e., earliest allowable response times, are repeatedly determined and compared to time elapsed from a selected reference time. When the current time exceeds the eartime, for a given inquiry signal, a response signal is generated by the transponder electronics and is transmitted to the inquiring ground station. Eartimes are based upon predetermined criteria of allowable response rates in selected time periods.

Abstract: A radio position determination and message transfer system is implemented using a pair of satellites in geostationary orbit for relaying interrogation and reply signals between a ground station and a user-carried transceiver. The user position is calculated based on the arrival times of reply signals received at the ground station via the two satellites, the known transmission time of the interrogation signal from the ground station, and the user's elevation on the surface of the earth. The elevation is derived from a stored terrain map providing local terrain elevations at a plurality of points on the earth's surface. The stored terrain map allows accurate position fixes to be obtained for surface users regardless of the deviation of the local terrain from the spherical or ellipsoidal model of the earth's surface.

Abstract: An aircraft position determining system including an on-board radio altimeter which cooperates with a ground based transponder/beacon located at a position A. The radio altimeter is adapted as a distance meter and comprises means (9, 14, 15, 16) for shifting the frequency of the local oscillation signal. The system has a range sufficient to enable it to operate in a second predetermined volume defined with respect to the position A which includes a first volume defined by the lateral distance accuracy (d) and vertical distance accuracy (h) of the position determined by an independent on-board guidance device. The exact position of the aircraft when close to A is determined by at least two successive measurements of distance from to the position A.

Abstract: A navigation system including at least one pulse radar and a number of transponders which when receiving radar pulses transmit high frequency pulse modulated signals. When receiving an interrogating signal from the pulse radar the transponder transmits a response signal with a delay. The delay is selected in such a manner that the response signal arrives at the pulse radar within a time space lying between the moment when all signal echos, lying within a definite range, have been received and the moment when the next radar pulse begins. The display scan in the radar is delayed by the same value as the response signal. In this way the response signal competes with considerably weaker echo signals than in the case of a non delayed response.