Abstract: A method and system for conducting local neighborhood searches among three or more aircraft routes to cure any irregularity in one of the aircraft routes, in which states of Binary Operations are stored, time and space feasibility tables are created from the stored states, and Tertiary Operations responsive to data stored in the feasibility tables are performed on the three or more entities to effect a repair.

Abstract: The invention relates to a device for the linearization of a frequency modulation ramp comprising a voltage controlled oscillator associated with a phase locked-loop. The device comprises a digitally controlled oscillator of which only the most heavily weighted bit is used, and a digital phase comparator receiving, on the one hand, said most heavily weighted bit and, on the other hand, a signal supplied by the voltage controlled oscillator. Application to very high linearity and very high accuracy radio altimeters.

Abstract: A method and apparatus are provided to allow altimeter data sets from multiple altimeter satellites to be used together. The measurable portion of geographically correlated orbit error (GCOE) is removed from the altimeter data sets, thereby allowing the data sets to be combined consistently. The GCOE structure for a reference data set is estimated through crossover difference analysis. The unmeasurable portion of the GCOE is not removed, although the spatial structure of this portion is determined. A reference mean sea level (SL) is corrected for the measurable GCOE and is then used as a reference surface for estimating the GCOE structure for an independent altimeter data set. This is performed by examining crossover differences between the altimeter mean SL and the reference mean SL at the multimission crossover points. The change in sea surface height (SSH) between the input data set and the reference data set is determined.

Abstract: A portable, handheld electronic navigation device includes an altimeter, a compass, and a GPS unit. An internal memory stores cartographic data, for displaying the cartographic data on a display of the navigation device. Accordingly, the device is capable of displaying cartographic data surrounding a location of the unit as determined by GPS, heading information as determined by the compass, and altitude information as determined by the altimeter. Additionally, through operation of an input, a user can cause the display to move, and thus display additional cartographic information, in the direction of the compass heading even when the user of the device is standing still. Furthermore, through utilization of a clock, such as the GPS clock, a user can determine altitude changes over time. Also, the altimeter of the navigation may be calibrated with altitude information entered by a user, with altitude information obtained from the cartographic or with altitude information derived from GPS.

Abstract: A radar altimeter for determining altitude of an air vehicle comprises a transmitter for transmitting radar signals toward the ground. A first and a second antenna receive reflected radar signals from the ground. A signal processor is coupled to the first and the second antennas. The signal processor includes filter means for rejecting signals other than signals reflected from a selected ground swath. The signal processor determines the above ground level altitude of the air vehicle based on the radar signals output from the filter means. A phase ambiguity resolution means resolves phase ambiguities that arise due to multiple wavelength separation of the first and the second antenna. The signal processor also determines the horizontal position of the highest point in the selected ground swath.

Abstract: The present invention concerns a method and a device (1) operating by intepolation in a discrete spectrum to determine characteristics Pq of a signal s(t,Pq). In accordance with the invention, said device (1) includes means (2, 4, 6, 8, 10, 12) for determining said characteristics Pq from a system of m equations: z(fi)=Fi[w(t).s(t,Pq)].h(f), i varying from 1 through m and m being greater than or equal to 2, wherein: z(fi) is an element of a discrete spectrum obtained by Fourier transformation of the signal s(t,Pq), Fi is a discrete Fourier transform, w(t) is a temporal weighting function, and h(f) is a frequency transfer function of an anti-aliasing filter.

Abstract: A baro altitude and terrain warning system with an integrity monitoring function which uses a radar altimeter to generate instantaneous altitude signals used to confirm the validity of a baro altitude signal, generated by a baro altimeter and an expected terrain clearance signal, provided by the terrain warning system, and for generating an alert when insufficient correlation exists between such signals.

Abstract: A random signal radar unit transmits a variable signal modulated by random noise (at 41). The return signal from the target area is correlated (at 61) with a sample of the transmitted signal, effectively compressing the spread spectrum waveform into a narrow band signal. The result is a covert high resolution radar which can be instrumented to operate in a number of single-or multi-mode configurations. By randomly varying biphase modulation (at 41, 35) and by down beating (at 49) the echo signal with the modulation delayed by a time equivalent to that of a leakage delay, a random signal is produced (at 35, 39) in which leakage return signals are readily filtered (at 53, 59).

Abstract: A random signal radar unit transmits a variable signal modulated by random noise (at 35). The return signal from the target area is correlated (at 61) with a sample of the transmitted signal, effectively compressing the spread spectrum waveform into a narrow band signal. The result is a covert high resolution radar which can be instrumented to operate in a number of single-or multi-mode configurations. By randomly varying biphase modulation (at 41, 35) and by modulating (at 49) the echo signal with the modulation delayed by a time equivalent to that of a leakage delay, a random signal is produced (at 35, 39) in which leakage return signals are readily filtered (at 53, 59).

Abstract: FMCW doppler radar, in which a reference signal is generated from the transmit signal via a delay line and a mixer. A measuring signal which is received and mixed with the transmit signal is detected and digitized at the times of the zero crossings of the reference signal. In this way, the measuring signal can be evaluated at time intervals of equal phase of the reference signal. A downstream algorithm enables the generation of a strictly linearly frequency-modulated transmit signal. With this mechanism, phase errors of conventional radar systems are eliminated.

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: The apparatus has the capability to detect the distance between an aircraft and the ground and at the same time to the nearest point to the aircraft such as buildings or trees. The apparatus includes an altimeter, determining the nearest point, as well as a device for determining the distance to the second target.

Abstract: A radar ice sounder which employs parallel Doppler processing obtains more reliable and accurate radar ice sounding. The invention uses both incoherent and coherent techniques, in the same paradigm, to achieve simultaneously high Signal-to-Noise Ratio, high Signal-to-Speckle standard deviation Ratio, and high Signal-to-Clutter Ratio.

Abstract: A positioning and ground proximity warning method for vehicle includes the steps of outputting global positioning system signals to an integrated positioning/ground proximity warning system processor; outputting an inertial navigation solution to an integrated positioning/ground proximity warning processor; measuring air pressure, and computing barometric measurements which is output to the integrated positioning/ground proximity warning processor; measuring time delay between transmission and reception a radio signal from a terrain surface, and computing radio altitude measurement which is output to the integrated positioning/ground proximity warning processor; accessing a terrain database for obtaining current vehicle position and surrounding terrain height data which is output to the integrated positioning/ground proximity warning processor; and receiving the position, velocity and time information or said pseudorange and delta range measurements of said global positioning system, the inertial navigation s

Abstract: An equivalent time pulse-echo radar or other pulse-echo system employs a transmit reference sampler collocated with the transmitter to provide a transmit reference pulse, which initiates a pulse width modulated (PWM) pulse. A receive sampler connected to a receive antenna provides an echo-detection pulse that terminates the PWM pulse, such that the width of the PWM pulse indicates target range. The transmit reference sampler and the receive sampler are driven from a common clock such that transmit-receive timing offset drift precisely cancels on a picosecond scale, thereby enabling sub-mm range accuracy with common, low-cost circuit elements. The radar further includes automatically referenced pulse detectors that are responsive to either the magnitude or the phase of the sampler outputs. The radar can be used for precision tank level measurements, robotics, or automotive ranging applications.

Abstract: A continuous wave radar system, for example a radar altimeter, comprises a memory (24) for storing an array of return signals, means for performing a time integration (25) of the array to improve its signal-to-noise ratio, means responsive to the time integrated array (26) to compare (30) the noise level (28) thereof with the peak level (27) thereof to obtain the signal-to-noise ratio of the array, and control means (31) responsive to the signal-to-noise ratio thus obtained to set either the period over which the said time integration is performed for each renewal of the time integrated array (26), or the power of the transmitted signal, of both, in accordance with predetermined criteria to the minimum necessary to ensure an adequate signal-to-noise ratio.

Abstract: A procedure for independently reducing acquisition thresholds and tracking spread spectrum codes received in orbit by a receiver accessing an orbital navigator (internal or external to said receiver), wherein the receiver includes a phase loop and a code loop. The code loop that tracks the pseudo-random codes is "impelled" by a fine velocity aid and corrects the error between the real and calculated velocities. The code loop receiving pseudo-random codes is similarly "impelled" by the fine velocity aid, the code phase search being based on a phase prediction maintained by the fine velocity aid provided by the orbital navigator.

Abstract: To ensure that a radio altimeter indicates zero altitude when the aircraft is on the ground, an on-ground calibration system utilizes a calibration switch to initiate a calibration radio altimeter signal from the radio altimeter's transmitter section which is reflected off of the ground and received by the altimeter's receiver section. The time delay between transmission and reception of the signal is measured and a value representing the delay is stored in the altimeter's microprocessor. This value corresponds to zero altitude and can be used as the relative zero point for calculating altitudes of the aircraft when it is in flight.

Abstract: An altimetric type measurement method for use on a satellite transmits a pulse towards the surface of the sea and carries out frequency transformation on the return signal resulting from the reflection of this pulse at the surface of the sea. This produces a spectral signal of samples successively comprising:(a)--a first zone with a low amplitude level,(b)--a second zone with a sharply increasing slope ending at a peak, and(c)--a third zone of decreasing slope.Samples of the spectral signal are selected within a selection zone that corresponds to the first and second zones for a predetermined maximal level of the height of the waves at the surface of the sea and maximum likelihood processing is applied only to the selected samples.

Abstract: A continuous wave radar altimeter comprises a pulsed power control (4), operable when the signal-to-noise ratio of the received signal is likely to be too low, to pulse the transmitted power so that the power varies between a non-zero base level and a higher level. The receiver channel (13, 14) is switched off during each transmitted pulse.

Abstract: An apparatus for measuring the height and cross-track offset of a surface location from a moving platform is defined. First and second antennas positioned on an underside of the platform are directed downwardly toward the surface. A transmitter associated with one of the antennas transmits a signal toward the surface. A first coherent detector associated with the first antenna detects a received signal corresponding to the transmitted signal as reflected by the surface and generates in-phase and quadrature components of the detected signal relative to the transmitted signal. A second coherent detector associated with the second antenna detects a received signal corresponding to the transmitted signal as reflected by the surface and generates a second set of in-phase and quadrature components of the detected signal relative to the transmitted signal. An analog to digital (A/D) converter converts the in-phase and quadrature components into digital information stored in a memory.

Abstract: Method and apparatus for determining the attitude or angular orientation of a moving vehicle or other moving body, using either two spaced apart antennas or a single antenna attached to or connected with the vehicle. Where two antennas are used, the spatial locations of each antenna are determined at a first selected time, and the spatial location of one antenna is determined at a second selected time. These three spatial locations determine a plane whose normal vector allows determination of the vehicle attitude at a time determined by the first and/or second selected times. Four or more spatial locations can also be used to determine a plane that indicates vehicle attitude. Where one antenna is used, for example, in a vehicle turn, the antenna spatial locations at three distinct selected times determine a plane that allows determination of the vehicle attitude at a time determined to the first, second and/or third selected times.

Abstract: A continuous wave radar altimeter comprises a memory (24, 26), means for storing in the memory in digital form an array of return signals representative of the variation of reflected amplitude with path length, means (27), for addressing the memory for identifying a peak return representative of the highest objects on the terrain, means (28) responsive to the array for determining the signal-to-noise ratio thereof, and means (29) responsive to the height at which the said peak return occurs and to the signal-to-noise ratio to determine a "center of area" height representative of the lowest surface on the terrain. The altimeter thus provides not only the peak level, representing for example the tops of trees and buildings, but also the ground level.

Abstract: A delay compensated Doppler radar altimeter which eliminates the relative delay curvature associated with the energy reflected by a scatterer located in the along-track direction of an aerial platform for which a most accurate estimation of scatterer elevation is desired. By Doppler shifting each return, the range indicated for each scatterer over its illumination history is equal to the minimum range x.sub.h experienced when the relative velocity between the aerial radar and the ground is effectively zero. Compensating each signal so that its entire along-track history can be used for elevation estimation leads to an advantage of more than 10 dB in gain improvement over existing systems, and less degradation from surface topography.

Abstract: A method of detecting the displacement of a target in a given environment includes storing reference data having data representative of the environment; transmitting a transmit signal towards the target; sensing the return signals from the target and the environment; and detecting the displacement of the target by comparing the return signals and the stored reference data. A method of detecting the level of a sample in a container is also disclosed. Analogous apparatus features are also disclosed.

Abstract: A continuous wave ranging system comprises a modulator for modulating an r.f. carrier signal in accordance with a pseudo random code, a transmitting antenna for radiating the signal towards a target, a receiving antenna and receiver for detecting the signal reflected from the target, a correlator for correlating the detected signal with the transmitted code with a selected phase shift corresponding to the current range gate to be tested, whereby the range of the target from the system may be determined, and filtering means for filtering from the output of the correlator those range gate amplitudes which vary with a frequency less than a predetermined value.

Abstract: A relatively low-cost FMCW radio altimeter includes a voltage-controlled oscillator based upon a GaAs FET. The oscillator produces, for example, a 4.3 GHz microwave signal that is modulated with a triangular wave having a pin-selectable modulation frequency. The modulated signal is amplified by a buffer amplifier, as well as a power amplifier, and connected to an RF output terminal by way of a plurality of microstrips. Reflected signals are received at an RF input and are coupled to a mixer by way of a low-noise amplifier. The modulation signal is also applied to the mixer by way of a microstrip coupling device to produce an audio output signal whose frequency is proportional to the altitude above ground. The gains of all of the amplifiers are selected to eliminate the need for hand-tuning of the microstrips and to enable the use of a glass/epoxy circuit board.

Abstract: A radar altimeter system uses a microprocessor-based subsystem to process radar signals in software. The subsystem includes a track loop and a verify loop for digital signal processing of the radar signals. The track loop generates a gate pulse and integrates a radar return signal over the time window defined by the gate pulse in order to determine the leading edge of the return pulse. The verify loop positions the gate pulse for maximum overlap with the return pulse and integrates the return pulse over the gate pulse to determine the maximum signal strength of the radar return signal.

Abstract: An enhanced system for calculating the Z-Axis, or relative height or altitude, of a radio beacon. The present invention uses a barometric pressure sensing device co-located with the radio emitter to transmit data representing relative altitude. To further enhance the Z-Axis determination, one or several barometric sensors, located at known heights, are positioned around the city to provide real time barometric data. This real time data is used to form a differential correction factor which is compared to the to the time varying barometric sensor co-located with the radio emitter, thereby yielding Z-Axis accuracies of up to one (1) foot. Since the altitude essentially becomes a "known", this information can also be used in the least squares fit algorithm to enhance the X and Y determination as well.

Abstract: An altimetry method uses one or more sources of opportunity, for example transmitters on satellites of the "GPS" satellite navigation system. One or more receivers on board an aircraft or a satellite in low Earth orbit are used. Multiple correlation is applied between the direct signal received from the transmitter and the reflected signal. The coordinates of the point of specular reflection are derived from the measured delay achieved by said multiple correlation and comparison with a theoretical model of the terrestrial sphere. The device for implementing the method includes a signal processor, a variable delay circuit, a discrete delay line, a bank of correlators and detectors. A specific application of the method and device is ocean altimetry.

Abstract: An altimeter system for aircraft employs an aneroid, dash mounted altimeter having a needle coupled to an encoder. The encoder provides a signal indicating that the needle points to a certain altitude. A solid state transducer senses outside pressure and supplies a signal to a signal processor, which instructs a transponder to transmit an ICAA coded altitude signal. When the signal from the encoder is provided to the signal processor, it compares the altitude from the needle position with the altitude that is squawked. If the error exceeds a value stored in the signal processor, a fault is indicated to the pilot and squawked. If the error is within the stored value, an offset is computed from that value and is summed with the needle altitude and the sum is squawked. The squawked altitude is the value between the altimeter reading and the altitude indicated by the transducer.

Abstract: A low cost frequency modulated (FM) radar altimeter system with enhanced accuracy for continuously providing an altitude of a target, comprising a transmitter means for transmitting a carrier modulated output signal towards the target; a receiver means having an altitude output signal for receiving the carrier modulated output signal reflected from the target after a time delay, and for providing an open loop error correction means for correcting errors resulting from nonlinearities in the transmitter means and signal processing delay variations in the receiver means so that the altitude determined is accurate; a coupling means for directing a portion of the carrier modulated output signal to the receiver means, and searching means having a first output directed to the receiver means and a second output directed to the transmitter means and having a symmetrical search output signal with a slope, s.sub.

Abstract: The calibration apparatus (16) includes a recirculating optical delay loop (22) constituted by two delaying fibers (F2, F3), an optical amplifier (28), and a coupler (26) for providing a succession of a plurality of delayed optical signals (OR) in response to a single initial signal (OA). The invention is particularly to radars.

Abstract: A terrain clearance signal generator particularly usable with ground proximity warning systems provides a signal representative of terrain clearance when the radio altimeter signal is unreliable, such as in the case of excessive pitch or roll, out of track or other conditions resulting in invalid readings. The system monitors such conditions and takes a sample of the last valid radio altitude reading prior to sensing an invalid condition and, upon sensing an invalid condition, updates the sample utilizing barometric altitude signals or integrated barometric altitude rate or inertially-derived Z-velocity signals.

Abstract: A method and apparatus for performing on-board corrections to the computed navigation variables of an inertial system on an aircraft while flying over a body of water. Onboard instruments, including a barometric altimeter and a radar altimeter, measure the vertical distance of the aircraft above an ellipsoidal model of the earth and above the body of water respectively. An on-board computer calculates the differences between such heights over a plurality of points along the path the aircraft travels over the water as indicated by its inertial navigation system. The differences are compared with a map of the undulation of the geoid encompassing the region to determine the deviation of the navigated course from the true course. Appropriate corrections to the aircraft's inertial system may then be made to reduce error.

Abstract: A radar altimeter incorporates circuitry for automatically adjusting altitude readings for variations caused by altitude and temperature changes. Normal target tracking of the radar is intermittently interrupted and a calibration sequence is interjected. The current altitude and receiver AGC information at the time of each interruption is temporarily stored and a test is initiated in which a pseudo radar return at that altitude is introduced to the receiver. The receiver operates on the pseudo return as it would on an actual return. The transmit power is adjusted automatically for the correct signal level at the tracker. The resultant altitude measured for the pseudo return is compared to a known test altitude and any difference is stored away as a correction factor to be applied to the altitude reading which had been stored at the time that its operation had been interrupted to perform the calibration test.

Abstract: A pulse Doppler radar altimeter designed to resolve the ambiguous range problem associated with the use of a pulse repetition interval, which is less than the aircraft altitude, includes a radar transmitter configured to transmit first and second series of pulses where the first series has a pulse repetition interval slightly different from the pulse repetition interval of the second series. At a time when the first series is being transmitted, the receiver electronics including a range gate and a tracker searches for ground returns and positions the range gate in time coincidence with the detected ground return. Control then shifts so that the second series of pulses is transmitted and a determination is made whether overlap of the range gate with the ground return from the second series corresponds to the same altitude as when the first series was involved.

Abstract: A method for preventing errors in the Doppler radar measurement of velocity in aircraft that result from the radar receiver being locked to backscatter from side lobes of a plurality of main lobes radiated in a fixed radiation geometry. The inertial vertical velocity component (V.sub.IZ) obtained by a baro-inertial control loop is compared with the vertical velocity component (V.sub.DZ) determined from the Doppler frequencies to derive an error detection signal. When the error signal occurs, the inertial vertical velocity component replaces the corresponding velocity component supplied from the Doppler system while the horizontal velocity components are determined, for example, from the last calculated wind and the corresponding airspeed components, for the duration of the error signal.

Abstract: An aircraft radar altimeter includes a programmed microcontroller which permits effective simultaneous tracking of at least two targets such that, for example, both ground and obstacles on the ground can be simultaneously tracked, thus avoiding crashes when the aircraft is operating at very low altitudes. The microcontroller is operatively coupled to the radar transmitter and to the receiver so that information relating to a first target can be stored away while a search and track operation is run on a second target. The information concerning a detected second target is likewise stored away and the microcontroller permits alternate tracking of the two targets with the stored information being used as the basis for establishing an initial position for a target when tracking of that target is resumed.

Abstract: A high frequency signal is converted to a signal characteristic of two simultaneously present, closely spaced high frequency signals. A high frequency signal is passed through a controllable bi-phase modulating switch. The switch is controlled by the resultant output of a multiplier which multiplies the sign of two phase-related pulse trains.

Abstract: The radar system of the FM/CW type transmits a wave which has a virtually linear frequency, between two frequencies f.sub.1 and f.sub.2 and supplies a first beat signal (Fb.sub.1) between transmitted and received waves; it is suitable for measuring the altitude h by measuring the overall phase rotation. According to the invention the radar supplies a second beat signal (Fb.sub.2) in quadrature with the first signal; the signals Fb.sub.1 and Fb.sub.2 are digitized (23 to 26) and comparing means (36) compare the consecutive samples of Fb.sub.1 and Fb.sub.2, then calculating means (37) derive therefrom by means of successive increments/decrements the number of zero crossings of the phase plane in a predetermined direction minus the number of zero crossings in the opposite direction (result m). The calculated altitude h is proportional to m.

Abstract: A pulsed coherent radar altimeter is described which employs a narrow band receiver and utilizes a novel digital coherent pulse generator. A coherent pulse radar transmits a pulse comprised of the sum of at least two phase related RF signals closely spaced in frequency. The phase shift due to platform motion and return surface irregularity of the return signal is approximately the same for each carrier. The receiver produces a signal representative of the difference of the two carriers which is substantially free of decorrelation effects, and which can be processed in a narrow band receiver to produce range information.

Abstract: A method and apparatus is disclosed for passively determining altitude above the ground of an aircraft by use of an active emitter carried on a second higher altitude aircraft. Specifically, the altitude of the aircraft is determined by measuring the time difference between direct path radiation and reflected path radiation, taking into account the distance between an upper antenna which receives the direct path radiation and a lower antenna which receives the reflected path radiation and the angles of travel relative to the vertical between the direct path radiation and the reflected path radiation.

Abstract: Disclosed is a radar apparatus including the circuitry for synchronizing a first and second pulse train, having the same pseudo random coding. The apparatus comprises a programmable delay responsive to a control signal for selectively advancing and retarding a pulse train by monotonic increments. A positive and negative range gate is utilized in passing the video signals in opposite senses in order to generate a command signal for bringing the pulse trains in synchronization.

Abstract: A Doppler navigation system includes an altimeter section with increased accuracy resulting from closed loop operation of signal processing portions for reflected signals including phase shift information. Quadrature processing of the reflected signal includes compensation for differences between quadrature processing channels, wherein the reflected signals are periodically processed by alternate ones of the channels. A maximum amplitude signal is forwarded by the signal processing portions to a frequency tracker of the navigation system. Periodic calibration of the altimeter section corrects for delays introduced in the signal processing portions. Effects of FM to AM conversion in a Gunn oscillator are reduced by connection of the signal processing portions to a short circuit during the calibration periods.

Abstract: Stable measurement of terrain-height variations is provided by this radar system which employs a very low power spread spectrum transmitted signal which, after reception, is processed digitally for extremely stable and predictable performance. The system also includes an automatic power control circuit to maintain the transmitted power at the minimum required level.

Abstract: This arrangement comprises a fixed frequency emitter circuit (10) for directing a wave (12) to a surface (2) by means of a transmission antenna (11), a receiver circuit (25) for receiving by means of at least one receiving antenna (23) the wave (12) returned by the surface, and a processing circuit (30) for processing the return wave and enabling production of an indication of the velocity. The processing circuit has two branches (50 and 54), a direct branch for applying the received signal to one input of a multiplying member (52), and a delaying branch for applying the received signal to the other input of the multiplying member after having produced a delay t.sub.0 relative to the direct branch. A frequency estimating element (60) receives the multiplying member output signal and a calculation member (62) produces the indication of the velocity from the estimating member output signal and of the distance "h".

Abstract: Improved radar guidance system for the navigation apparatus of an aircraft s it flies over substantially flat terrain with random and different features. The system is generally made up of an airborne radar altimeter, a video signal processor and a master processor. The altimeter transmits a series of pulses at predetermined time intervals for impacting a plurality of spaced points along the aircraft ground track. The echo signal of each pulse-impacted point processor divides the amplified signal into corresponding signals. A comparator of the signal processor transforms one of the divided signals into a constant output. A track and hold arrangement of the signal processor correlates the delayed leading edge of the comparator output with the other of the divided signals so as to determine a point of intersection therebetween.

Abstract: An automatic landing system for landing remotely piloted flying vehicles ng a predetermined path and at a predetermined point. The system includes an autopilot carried by the flying vehicle for measuring the parameters of attitude, airspeed, and heading and for comparing the measured parameters with the inputted parameters for the desired attitude, airspeed and heading. The autopilot adjusts the vehicle controls to make it conform to the desired attitude, airspeed and heading when deviations therefrom are detected. The system includes a radar transmitter and receiver means disposed on a stabilized double gimbal for measuring the actual heading and distance from the vehicle to the radar transmitter and receiver on a continuous basis.

Abstract: A variable radar altimeter test system for providing a test of the altime portion of a flying object guidance system which simulates actual flight conditions includes an antenna connection to receive a signal from the flying object being tested, a synthesizer for generating a signal programmed to simulate data characteristic of a radar return signal, pulse modulation of the programmed signal to create a third signal which is returned to the flying object under test to stimulate the altimeter portion of its guidance system.