Abstract: The present invention is provided with: an antenna 23 having an antenna surface 28 for radiating radio waves so as to have a prescribed plane of polarization; a second rotary mechanism 22 which is connected to the antenna 23 and which rotates the antenna 23 about a second rotation axis I2 that is set in a normal direction orthogonal to the antenna surface 28; and a first rotary mechanism 21 which is connected to the second rotary mechanism 22 and which rotates the antenna 23 and the second rotary mechanism 22 about a first rotation axis I1 that is set in a direction slanted with respect to the second rotation axis I2.

Abstract: An imaging system is provided for monitoring a field of view with a two-dimensional array of photo elements on which the field of view is imaged. The imaging system determines for each photo element a distance between the photo element and a surface of an object in the field of view by light emitted into the field of view and subsequently arriving on the photo elements and to determine a distance vector to form a coordinate image that includes the distance vector. A first memory unit stores the coordinate image, a second memory unit stores logical relations for the photo elements. A processing unit determines for each of the photo elements whether a logical relation is fulfilled and outputs a trigger signal when at least one of the logical relations is fulfilled.

Abstract: A monopulse antenna system can include a monopulse detector assembly (MDA) that is configured to steer a monopulse antenna based on the magnitude of an elevation ratio or azimuth ratio independently of the phase of the ratio. To prevent the direction of the monopulse antenna from being changed too frequently, the MDA can employ ratio bins to determine when the direction of the monopulse antenna should be reversed. Also, the MDA may enforce a hold period during which a change in the direction of the monopulse antenna will not be performed. The MDA can employ one or more mapping equations to generate a steering signal as a function of the magnitude of the ratio. The mapping equations can be selectively employed based on whether tracking is being performed at or near the ratio null.

Abstract: A detection wave from a transmitting/receiving means is guided to the interior of a blast furnace via an antenna and a reflecting plate, and when a reflected wave from the surface of a loaded material is reflected by the reflecting plate and received by the transmitting/receiving means, the reflecting plate is rotated together with the antenna, or the reflecting plate is rotated additionally, and the surface profile of the loaded material is measured by scanning the surface of the loaded material in a linear manner or a planar manner during the turning of a chute or for each prescribed turn of the chute. A deposition profile is obtained on the basis of this surface profile and is compared to a predetermined theoretical deposition profile, and the chute is controlled so as to correct the error with respect to the theoretical deposition profile and then which new loaded material is introduced.

Abstract: A transmission system that can continue communication even if a tracking error exists and to reduce interference on other transponders when transmitting a video and audio between an endstation facility and another endstation facility via a transponder mounted on communications satellite. This transmission system includes a tracking antenna that tracks a transponder, a tracking error calculation circuit that obtains a tracking error in a tracking operation of the tracking antenna, a transmission level control circuit that obtains a transmission level of a signal in response to the tracking error, and a transmitter that transmits the signal at the obtained signal level via the tracking antenna to the transponder of the communication target.

Abstract: Systems, methods, and computer program products for optically identifying hostile fire strikes to a vehicle. The identification can be that the hostile fire will hit the vehicle, will likely hit the vehicle, hit the vehicle, or likely hit the vehicle. In the case of predictive hits, a warning may be output and the vehicle can take evasive and/or countermeasure actions. In the case of actual or likely strikes to the vehicle, the optical identification can map a travel path of a detected projectile to positions on the vehicle, thus identifying a likely position or area of projectile impact. Such data can be used for inspection and maintenance purposes.

Abstract: Methods and systems of determining the altitude of an aircraft are provided. The method includes receiving data associated with aircraft position, a position of a first point and a second point on the runway, and an altitude of the first point and the second point, radar returns from the runway. The method includes determining a first range and second range between the aircraft, and the first point and the second point. The method includes determining a first angle and a second angle between the first point and second point, and the aircraft. The method includes determining a corrected angle. The method includes determining the altitude of the aircraft based on the corrected angle, the runway altitude of at least one of the first point and the second point, and at least one of the first range and the second range.

Abstract: A multi-band low-profile, low-volume two-way mobile panel array antenna system is described. Operation of the antenna may automatically switch between bands based on various user-entered parameters.

Abstract: A method for processing signals of an airborne radar includes a correction of the erroneous angle of pointing of the radar beam, comprising an evaluation of the error in the pointing angle for a constant height of the aerial transporter. For a given angle of scan, the method carries out at least two series of measurements of the power of the echoes returned following the emission of radar signals, each series being associated with a given distance-bin, the measurements being dependent on the angle of pointing of the radar antenna, formulates a vertical profile of the power of the echoes returned for each series of measurements, and then on the basis of each vertical profile, measures the pointing angle corresponding to a power of the echoes returned by the ground alone, and calculates the error in the pointing angle on the basis of the measured pointing angles.

Abstract: The disclosed approach provides a low-cost approach by employing a single channel receiver for a direction-finding missile, rather than a conventional four-channel system. It employs interferometry techniques. The proposed approach leverages orthogonal waveforms and pseudorandom noise (PN) codes. This is a low-cost approach for a single channel direction finding system by leveraging orthogonal waveforms and interferometric techniques.

Abstract: The terminal apparatus has: base station and terminal error information generating means for generating base station and terminal error information indicating a rate of the base station and terminal frequency difference with respect to the official frequency; geostationary satellite and terminal difference information generating means for generating geostationary satellite and terminal difference information indicating a geostationary satellite and terminal frequency difference; geostationary satellite and terminal error information generating means for generating geostationary satellite and terminal error information indicating a rate of the geostationary satellite and terminal frequency difference with respect to the geostationary satellite frequency; base station frequency error information generating means for generating base station frequency error information indicating a frequency error of a transmitting radio wave from the communication base station based on the base station and terminal error.

Abstract: The terminal apparatus has: base station and terminal error information generating means for generating base station and terminal error information indicating a rate of the base station and terminal frequency difference with respect to the official frequency; geostationary satellite and terminal difference information generating means for generating geostationary satellite and terminal difference information indicating a geostationary satellite and terminal frequency difference; geostationary satellite and terminal error information generating means for generating geostationary satellite and terminal error information indicating a rate of the geostationary satellite and terminal frequency difference with respect to the geostationary satellite frequency; base station frequency error information generating means for generating base station frequency error information indicating a frequency error of a transmitting radio wave from the communication base station based on the base station and terminal error.

Abstract: There is disclosed an elevation null command generator (ENCG) for use in airborne monopulse radar, and a novel missile guidance system made possible by use of the ENGC. The ENCG provides an accurate means of directing the elevation monopulse plane of a radar antenna at a patch of ground defined by a range signal generated within the radar or its associated equipment. It is shown that within the system range can define the elevation angle of concern. The ENCG includes a central range gate centered at the command range and a plurality of pairs of range gates, the two gates of each pair being time spaced before and after the central range gate, and has circuit means for normalizing the output of the range gates to eliminate the bias effects of strong targets adjacent to the monopulse null plane and ground surface intersection.

Abstract: A radar tracking apparatus and method are provided. The radar tracking apparatus includes an ?-? tracking filter, wherein the ?-? tracking filter includes: a tracking index unit calculating a tracking index for obtaining ? and ? filter gains of an ?-? tracking filter, based on changes in the measurement error covariance of a radar-measured value that occur when the measured value of target is converted from a polar coordinate system to a rectangular coordinate system; and a filter gain update unit calculating the variations of ? and ? filter gains, based on the partial differential coefficient of the changing rate of the ? and ? filter gains with respect to the changing rate of the tracking index and the variations of the tracking index, and updating the ? and ? filter gains.

Abstract: Respective demodulated outputs from a plurality of branches 11a to 11d are fed to corresponding error correction units 13a to 13d and error-corrected. The error correction units 13a to 13d feed error signals to error determination units 14a to 14d. The error determination units 14a to 14d determine the error-incidence situations of the respective branches 11a to 11d and then output the determination results to a coefficient generation unit 15. Based on the results of determination by the error determination units 14a to 14d, the coefficient generation unit 15 obtains the synthesis coefficients for the respective branch outputs. The synthesis coefficients correspond to the error-incidence situations of the respective branch outputs and are appropriate values including no errors. By synthesizing the respective branch outputs by use of the synthesis coefficients, error-free data can be reproduced.

Abstract: The automatic vehicle braking device is equipped with a braking force control processing portion which, based on the judgment result of a collision judgment processing portion and the judgment result of a steering avoidance judgment processing portion, imparts a turning property in a direction of head-on collision to the vehicle when the lateral position of the obstacle with respect to a travel route curve is large in a condition in which the driver is unconscious of a high possibility of collision between the vehicle and the obstacle and has taken no steering avoidance action yet. As a result, it is possible to reduce the speed of the vehicle and, at the same time, mitigate the damage suffered by the vehicle occupants at the time of collision.

Abstract: A traffic sensor is mounted at a fixed location to monitor multiple lanes of traffic. The traffic sensor (a) generates a programmable time-varying modulating signal; (b) generates a modulated microwave signal based on the programmable time-varying modulating signal; (c) radiates the modulated microwave signal in a radiation beam at an object; (d) provides a proportional calibration signal based on the modulated microwave signal; (e) measures parameters of the calibration signal, and (f) corrects the programmable time-varying modulating signal based on the parameters of the calibration signal.

Abstract: System for obtaining information about a vehicle or a component therein includes sensors arranged to generate and transmit a signal upon receipt and detection of a radio frequency (RF) signal and a multi-element, switchable directional antenna array. Each antenna element is directed toward a respective sensor and transmitter RF signals toward that sensor and receive return signals therefrom. A control mechanism controls transmission of the RF signals from the antenna elements, e.g., causes the antenna elements to be alternately switched on in order to sequentially transmit the RF signals and receive the return signals from the sensors or cause the antenna elements to transmit the RF signals simultaneously and space the return signals from the sensors via a delay line in circuitry from each antenna element such that each return signal is spaced in time in a known manner without requiring switching of the antenna elements.

Abstract: Techniques for puncturing symbols in a communications system. S symbols are received for a frame having a capacity of N symbols, with S being greater than N. P symbols need to be punctured so that remaining symbols fit into the frame. A number of puncture distances, D1 through DN, are computed based on S and P. A particular number of symbol punctures is determined for each computed puncture distance. P1 through PN symbol punctures are then performed at the distances of D1 through DN, respectively. For a more even distribution of the symbol punctures, each of the distances D1 through DN can be selected to be greater than or equal to a minimum puncture distance Dmin defined as Dmin=?S/P?, where ? ? denotes a floor operator. The symbol punctures at each computed distance can be performed together or distributed with symbol punctures at other distances.

Abstract: Methods and systems for estimating and correcting airborne radar antenna pointing errors. The methods and systems include predicting expected received power from at least one scattering source using terrain elevation information, transmitting a radar signal to the at least one scattering source, measuring received power from the at least one scattering source, determining an antenna pointing error based on the predicted and measured received power, and adjusting an antenna angle, an input value, or other components based on the determined antenna pointing error. The methods and systems also include a radar processing and control unit for predicting expected received power from at least one scattering source using a model of the radar power measurement process that includes terrain elevation information, for measuring received power from the at least one scattering source, and for determining antenna pointing error based on the predicted and measured received power.

Abstract: A weather radar system or method can be utilized to adjust a position of a weather radar system. The weather radar system can utilize processing electronics coupled to an antenna control system. The processing electronics can determine an error associated with the position of the weather radar antenna and adjust the position of the weather radar antenna in response to data related to returns received by the weather radar antenna and data related to expected returns.

Abstract: A method is described for detecting an object with target radar. After the first detection of an object, the antenna is tilted. The original direction towards the object is restored by electronically steering the emitted beam. The beamsteering is obtained by changing the frequency of the emitted signal. Thus, the object may be detected several times on different frequencies. The method is particularly applicable in search and track radars.

Abstract: A technique for boresighting an antenna mounted on a moving platform is described. The technique uses a concurrently moving calibration target. Target navigation data and platform navigation data are used to compensate for movement of the target and the platform. The antenna pointing direction is biased in a direction which provides a best signal quality, and the bias used to determine antenna boresight calibration factors. The boresight correction factors can be used for open loop pointing.

Abstract: A target tracking arrangement predicts the state of a target. The predictor may be a Kalman filter. In the presence of a target which is maneuvering, the prediction may be in error. A maneuver detector is coupled to receive residuals representing the difference between the predictions and the target state. The maneuver detector is matched to the predictor or Kalman filter to thereby tend to reduce the undesirable effects of system noise. The matching may be of the frequency response.

Abstract: A communication satellite cellular coverage pointing correction using uplink beacon signal is provided. A ground-based beacon transmits a monopulse tracking signal or a Traveling Wave Coupler (TWC) tracking signal to a specialized tracking feed section located within each uplink and downlink antennae of a satellite. From the monopulse or TWC tracking signal, a pointing correction is determined for each reflector, for example, the angle off boresight and the angle between the present beam direction and the target direction. Each reflector is then gimbaled to re-point the reflector to the target area. In this way, both uplink and downlink antennae are provided with closed-loop control over antenna pointing.

Abstract: One embodiment of the present invention relates to a system for correcting spacecraft thermal distortion pointing errors. The system comprises one or more spacecraft sensors located at positions on a spacecraft and which are adapted to measure spacecraft parameters at those positions. The system also includes a spacecraft distortion prediction module, which is adapted to generate expected spacecraft thermal distortion parameter values and expected antenna thermal distortion pointing errors. Further, the system includes a spacecraft parameter processing module adapted to generate measured spacecraft thermal distortion parameter values from the measured spacecraft parameters, and an antenna pointing error calculation module adapted to calculate antenna pointing error correction commands. Finally, the system includes an antenna pointing control module adapted to receive the antenna pointing correction commands and control the adjustment of the antenna pointing using the correction commands.

Abstract: Estimating an antenna pointing error includes receiving a signal sent from a reference located within a region. A polarization ratio is evaluated over the region. A minimum polarization ratio variance for the polarization ratio is established. A location corresponding to the minimum polarization ratio variance is identified. An antenna pointing error is estimated from the identified location.

Abstract: A reflected energy detecting device includes a transmitter for transmitting an electromagnetic signal and a receiver for receiving a reflected electromagnetic signal. An antenna may be operatively connected with the transmitter and the receiver for radiating the electromagnetic signal and capturing the reflected electromagnetic signal and the antenna may be movable. A main controller may be provided for controlling operation of the transmitter and the receiver and the movement of the antenna and the reflected energy detecting device may further include at least one platform. The at least one platform may support a remote reflector that is dimensioned and configured to redirect the transmitted electromagnetic signal in a desired direction and a platform controller that is configured to communicate with the main controller and to maintain alignment between the remote reflector and the antenna.

Abstract: An off-gimbal pointing system is improved using filtering of resolver and gyro responses respectively applied at the output of the resolvers and gyros for attenuating high frequencies resolver responses and gyro responses that effectively degrades the high frequency responses that are matched and above the control system bandwidth for improving the overall dynamic control of the off-gimbal pointing system for rejecting the affects of base motion disturbances and vibrations.

Abstract: A vehicle-mounted radar apparatus which periodically derives and registers successive momentary position values for a target object such as a preceding vehicle based on received reflected radio waves and derives final lateral position data by smoothing the momentary position data, judges when a degree of scattering of the registered momentary position values exceeds a first predetermined level and in that case derives corrected position data based on differences between envelope curve line values which are generated based on local extreme values of the momentary position data, and performs smoothing of the corrected position data instead of the momentary position data, to obtain the final lateral position data. If the target object is not estimated to be located directly ahead of the host vehicle along a straight route, the corrected position data are adjusted in accordance with relative positions and orientations of the target object and host vehicle.

Abstract: A method for adjusting a detection axis of an object detection system, wherein a disk-shaped adjusting member is fixed to a reference plane on an outer face of a casing, wherein the rotational position of the adjusting member is adjusted. The adjusting member has first and second base surfaces, between which a wedge shape is formed. Rotating the adjusting member finely adjusts the angle of the second base surface relative to the reference plane of the casing, thereby resulting in the direction of the second base surface coinciding with the direction of an object detection axis of a radar mechanism part fixed within the casing. The direction of the object detection axis can be adjusted in the horizontal direction by placing a level on the second base surface of the adjusting member and adjusting the mounting angle of the casing so the level indicates a horizontal direction.

Abstract: An airborne radar antenna system for detecting a target in a volume includes a tethered aerostat and an antenna that is supported above ground by the aerostat. The aerostat-based antenna is used for transmitting and receiving a radar beam into the volume to detect the target. Additionally, the system includes a ground-based transmitter that generates a beacon signal which monitors the antenna configuration at the aerostat. A computer then evaluates the beacon signal to create an error signal which is used to maintain a predetermined configuration for the antenna. The system also includes mechanisms for orienting the radar beam along preselected beam paths between the antenna and the volume.

Abstract: A method and bistatic synthetic aperture radar (SAR) imaging system generate an image of a target area without knowledge of the position or velocity of the illuminator. The system includes an illuminator to illuminate a target area with a null-monopulse radiation pattern interleaved with a sum radiation pattern. The illuminator adjusts the phase terms of the sum radiation pattern to maintain a static electromagnetic field pattern at the target area. A receiver receives the radiation patterns reflected from the target area and generates phase compensation terms by correlating a measured electromagnetic vector field with the known static electromagnetic vector field. The phase compensation terms are used to generate an image of the target area.

Abstract: In a radar system, sampled aperture data are received from an antenna array. The sampled aperture data include data that do not correspond to echo returns from a beam transmitted by the antenna. A covariance matrix is generating using the sampled aperture data. An eigenvalue decomposition is performed on the covariance matrix. A direction of arrival is determined from which at least one jammer is transmitting a signal included in the sampled aperture data, based on the eigenvalue decomposition.

Abstract: On an element-by-element basis, measure phases between signals at Port A to Port B of the antenna feed network to get a phase measurement angle that corresponds tp an angular difference between outgoing radar signals and target echo return signals; applying a least squares fit equation to the angular distance to get a correction phase slope across the array, &dgr;0, and applying a phase slope correction of &dgr; to the phases of the transmitted signal.

Abstract: A system identifies a number of targets within a main beam of an antenna array that transmits the main beam and receives echo returns from the main beam. A covariance matrix is generated using the echo returns. The presence of at least one target within a single range cell is detected. A plurality of consecutive pulses are transmitted in a direction of the single range cell within a sufficiently short period that the at least one target remains within the single range cell while the plurality of consecutive pulses are transmitted. An echo signal is sampled from each of the plurality of pulses. An updated covariance matrix is estimated each time the echo signal is sampled. An eigenvalue decomposition is updated each time the covariance matrix is updated. The number of targets in the single range cell is estimated, based on the updated eigenvalue decomposition.

Abstract: A method for accurately tracking and communicating with a satellite from a mobile platform, wherein the satellite has an antenna which performs both transmit and receive functions from a single antenna aperture. The method involves using an inertial reference unit (IRU) of the mobile platform to initially acquire the signal from the satellite. A sequential lobing process is then used to more accurately center the antenna aperture relative to the receive beam from the satellite. The antenna is then used to transmit data or other information, and the antenna pointing is maintained by an additional IRU local to the antenna with higher accuracy and lower latency than the IRU of the mobile platform. Periodically, transmissions from the antenna are inhibited and the sequential lobing process is repeated to eliminate for any inertial reference drift error.

Abstract: Disclosed is a method and apparatus for improving airborne vehicle tracking and guidance systems by reducing boresight error induced by polarization of the RF energy impinging on the vehicle radome. The radome wall is formed with a taper which gradually increases from the base near the vehicle antenna to the tip according to a disclosed formula which accounts for frequency, incidence angle, look angle, and the dielectric constant of the radome material. This taper of the radome minimizes the crossplane boresight error component magnitude which is polarization sensitive and produces a polarization insensitive inplane boresight error component. Also disclosed is a method of electronically compensating such radomes for boresight error where the radome boresight error data accumulated during testing is digitized and processed for compensating data in the vehicle electronic system to provide compensated tracking data for the vehicle guidance system.

Abstract: A system and method for aligning an antenna. Signals broadcasted over a number of channels for each of a plurality of orientations of the antenna may be received. From such received signals, information pertaining to at least one of (i) an error rate, (ii) a signal level, (iii) equalizer tap coefficients, and (iv) error correction for each orientation of the antenna for each channel is obtained and used to determine an acceptable orientation for the antenna for each channel.

Abstract: An RF beam pointing apparatus (500, 600) compensates for the effects of settling errors on antenna pointing. The beam pointing apparatus includes an attitude reference system (502, 528, 530, 534) generating an antenna attitude output from the satellite attitude. Also included is attitude comparison circuitry (528, 530), coupled to the attitude reference system, that includes an antenna pointing error output. Control circuitry (528, 530) is coupled to the attitude reference system (502, 528, 530, 534) and the attitude comparison circuitry (528, 530). The control circuitry (528,530) directs the attitude comparison circuitry (528, 530) to generate control error output signals in response to dynamic settling antenna pointing errors induced by a mechanical slew on the satellite.

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 and apparatus for estimating attitude sensor bias in a satellite system uses attitude sensors and a spacecraft control processor. Attitude sensors provide output signals, which may contain bias. The present invention interprets the signals, determines the bias present in the signals, and generates an output signal to offset the bias in the signals from the attitude sensors, thereby leading to more accurate positioning of the satellite employing the present invention.

Abstract: A satellite tracking method for a vehicle-mounted receiving antenna system to determine the orientations of satellites dependent upon the moving direction of a moving body such as an automobile associated with the attitude control of an antenna which is mounted on the moving body for the purpose of receiving satellite broadcasting signal, the method including an initial mode, a maximum value search mode, a normal tracking mode, an error correction mode, a signal blocking mode and a rainfall mode.

Abstract: A method for calibrating the radar system includes the steps of: replacing stored statistically generated "average" error correction coefficients with error correction coefficients personal to a missile under test. More particularly, stored in the missile's memory are: (a) first personalized error correction coefficients generated in response to test signals produced internal to the missile and injected into a monopulse arithmetic unit for the missile's receiver/processor; and (b) a second set of personalized error coefficients generated in response to test signals external to the missile and injected through the missile's antenna to the receiver/processor. The missile includes a radio frequency (R.F.) energy test signal generator for performing a test during the missile's flight to determine "in-flight" personalized error correction coefficients. The test is performed in-flight by injecting the R.F.

Abstract: A method and apparatus for controlling an antenna and a tracking antenna system using them. A rate sensor detects the angular rate of the vehicle turning. On the basis of the detected value, an error correction circuit determines the steering angle of the antenna. If it is judged from the determined angle that the vehicle is not turning or only slightly turning, a motor driving circuit suspends driving of a motor and at the same time a linear actuator locks a major gear. If it is judged that an accumulated error of a control target which is determined on the basis of the output of the rate sensor is not negligible, the error correction circuit starts a closed-loop control on the basis of a receiving signal level. In such a manner, the power consumption in the motor can be reduced.

Abstract: A maneuver detector and processing method for use in target trackers employed in weapon guidance systems, and the like, that employs multidimensional measurements and a set of inertial coordinate systems. The maneuver detector and processing method are implemented as follows. Time-delayed target position and velocity estimates of the target are maintained in a history file. These estimates are continuously updated, in that they are transformed 24 into intermediate north, east, down (NED) range Cartesian coordinate systems by correcting for aircraft motion. For each measurement time, the histories are used to predict the position and velocity of the target in an "observation-relative" inertial coordinate system aligned with the line-of-sight to the target. The error between the prediction and observation is calculated and used with the measurement accuracies to calculate a maneuver probability.

Abstract: A radar utilizes an antenna stabilization error correction system to automatically estimate and correct attitude sensor errors in pitch, roll and elevation. The radar system includes an antenna, an antenna positioner, a transmitter receiver, a signal processor, an antenna controller and stabilization processor and the antenna stabilization error correction system. As part of the normal signal processor sub function, ground clutter signals are extracted from the received signals. These signals are the primary input to the antenna stabilization error correction system. Other inputs are received from the signal processor, antenna controller and stabilization processor and an external aircraft radio altimeter. The antenna stabilization error correction system processes the signals and estimates pitch, roll and elevation errors which are passed back to the antenna controller and stabilization processor.

Abstract: This invention comprises the use of integral pulse frequency modulation (IPFM) reaction jet controllers for multi-axis precision tracking of moving objects with flexible spacecraft, and vibration suppression. Two sets of position, rate and accelertion command profiles for multi-axis tracking are disclosed: one for a payload initially facing the zenith and the commands based on a pitch-roll sequence; the other for a payload facing the nadir and the commands based on a roll-pitch sequence. The procedure for designing an IPFM controller for tracking a given, inertial acceleration command profile is disclosed. Important elastic modes of a spacecraft are identified according to their spontaneous attitude and rate response to the minimum impulse bit of the thrusters. The stability of the control-structure interaction is shown to be governed by the ratio of the moments of inertia of the flexible to the rigid portions of the spacecraft.

Abstract: An antenna is divided into a plurality of sub-arrays which are arranged parallel to each other on a turntable. At least one of the sub-arrays is laterally divided into sub-array sections. Reception signals from these sub-array sections are compared with each other to detect a phase difference therebetween. This phase difference is utilized to control the beam direction of the antenna such that the antenna can be properly oriented to the satellite at all times.

Abstract: A method for tracking a satellite in a land mobile satellite communications system is disclosed. A rate gyro is provided for use in the event that an automatic satellite tracking is prevented. The satellite is automatically tracked using a receive signal level if the receive signal level equals or exceeds a threshold. An output of the rate gyro is constantly compensated while automatically tracking the satellite. When the receive signal level falls below the threshold and the automatic satellite tracking becomes unable, the satellite is tracked using the compensated output of the rate gyro.