Abstract: A steerable antenna system for adjusting the elevation of an antenna for communication with a central facility via a satellite. The steerable antenna system includes a motor, a spindle drivingly engaged to the motor, and a chassis fixedly disposed on the spindle. The chassis has a stop disposed about its periphery. A first waveguide is fixedly disposed on the chassis and a second waveguide is disposed on an antenna. A ring cam is mounted on the chassis, and a grooved is formed in the ring cam. A first portion of a lever arm is pivotally mounted on the chassis and a second portion of the lever arm is disposed in the groove of the ring cam. An antenna is hingedly mounted on the chassis and to the lever arm. A solenoid, disposed on a base of the steerable antenna system, is configured to engage a portion of the ring cam. In use, when the solenoid is activated, power from the motor is used to adjust the elevation of the antenna.

Abstract: A telescopic mast is provided for deployably mounting a satellite dish to a vehicle. The telescopic mast preferably is secured to a rear surface of a truck cab or other vehicle. The satellite dish is deployable via extension of the telescopic mast. The telescopic mast includes a base tube secured to the back of the vehicle and a shaft telescopically mounted within the base tube. The shaft has a dish carrier portion adapted to carry the satellite dish. The shaft is telescopically movable between a first position wherein the dish carrier portion is higher than a roof of the vehicle, and a second position wherein the dish carrier portion is lower than the roof of the vehicle to thereby protect the dish carrier portion from exposure to wind generated by movement of the vehicle to protect the dish carrier portion from road debris. A releasable locking device selectively prevents telescopic extension and retraction of the shaft with respect to the base tube.

Abstract: A TV graphical user interface (GUI) is provided to enable a user to input antenna location information required for setting up a dish antenna. When the TV GUI is set in a dish set-up mode, the user may activate a U.S. map button to display a map of the United States or another area on the earth's surface. When a remote pointing device is directed at a point on the map that represents the current location of a satellite receiver, the TV GUI displays a regional map that shows in more detail a region where the receiver is located. When the user selects the receiver location within the regional map, the CPU determines the latitude and longitude values of the selected location, and calculates magnetic north and elevation angles for the antenna installation. To provide the user with visual feedback, the TV GUI may indicate the city nearest to the selected location, and a distance to the nearest city.

Abstract: An extended spatial acquisition method extends the spatial acquisition range for tracking antennas. The method employs a multiple feed cluster to sense the received signal with high sensitivity and to spatially acquire the received signal when uncertainty in the received signal arrival direction exceeds several beamwidths. A main beam consisting of a collection of beams including a central beam and surrounding beams of the cluster extend the spatial acquisition range to include the surrounding beams. Feed signal strengths are measured to determine where within the extended field of view a desired signal arrives and then the antenna is repositioned to point the central beam toward the desired signals after which central beam tracking occurs.

Abstract: A communications antenna assembly is disclosed, suitable for use in fixed antenna multiple access systems, such as fixed wireless access schemes and satellite communication systems. Such systems have independent base station transmitters which, in the case of fixed wireless access schemes, may be subject to over capacity and/or obstructions between the subscriber and the base station and, in the case of non-geostationary satellite communication systems continuously move. The antenna is operable to communicate with at least one of two communication stations at each of two directions from the antenna assembly, said assembly comprising: a beamformer connected to the antenna and arranged to allow the antenna to provide at least two antenna beams, one substantially in each of the communication station directions are provided substantially simultaneously, such that in use the antenna assembly can communicate with the two communication stations. A corresponding system and method of use is also described.

Abstract: A method for simulating RF energy distribution comprises obtaining a binary tree representation of a geometric environment in three-dimensions and forming a 3-D geometric database model therefrom, obtaining one or more specified receive locations within the 3-D geometric database model where RF energy distribution is desirable, simulating the propagation of an RF signal within the geometric database model, the RF signal being represented as a beam having magnitude and direction, the propagation including querying the database model to trace the beam in the geometric environment; and, determining one or more intersections of the traced beam with one or more receive locations to determine RF energy distribution at the receive locations.

Abstract: An antenna, forming a part of an antenna system, is suitable for use on a communication satellite encircling the earth, and has a reflector illuminated by a set of feed elements wherein one of the feed elements generates a primary beam. The reflector is shaped to establish a specific configuration of the beam, and, upon illumination of the earth, there results a specific shape to the beam footprint. A mechanical positioning device connects the antenna with a body of the spacecraft for adjusting an orientation of the feed antenna and its beam relative to the body of the spacecraft. Control circuitry for adjustment of signal strengths and phase shifts of signals sent to respective ones of the feeds is accomplished by electronic circuitry including a memory which stores coefficients employed in the operation of variable power dividers and variable phase shifters of a feed network supplying electromagnetic signals to the feed.

Abstract: A satellite dish antenna targeting device which corrects for incline and parabolic offset angle. The satellite dish antenna is connected to a base by a support member so that the satellite dish antenna is able to move through an elevation. An inclinometer is mounted to move in unison with the satellite dish antenna for sensing when the base is oriented at an inclination angle with respect to a tangent to the earth at a location where the satellite dish antenna is being targeted. The inclinometer further senses the elevation the satellite dish antenna moves through. The inclinometer thereby provides a dish elevation corrected for the incline and elevation of the satellite dish antenna to a microprocessor. The microprocessor corrects the dish elevation for the parabolic offset angle of the satellite dish antenna. A display device connected to the microprocessor displays a corrected dish elevation of the satellite dish antenna.

Abstract: A system and method for RF autotracking multiple antennas to compensate for disturbances experienced by the antennas. The system and method uses two control algorithms implemented in fast and slow controllers and sums the result for each antenna that is tracked. One (fast) control algorithm corrects for rapid, common mode disturbances such as spacecraft motion disturbances, while the other (slow) control algorithm corrects for slower disturbances, such as thermal distortion, that do not affect all antennas in the same manner.

Abstract: System and method for facilitating the positioning of an antenna adaptable for receiving transmitted signals wherein antenna alignment values obtained from equalizer tap-weight values are displayed so as to provide an indication as to whether or not the antenna is properly aligned. Such antenna alignment values may change gradually as the antenna is rotated or moved. As a result, an installer can easily position or point an antenna in the direction of the transmission site.

Abstract: A system for acquiring the beacon of a satellite and synchronizing data transmission between the satellite and a ground terminal is disclosed. The ground terminal conducts a search for a satellite to be acquired. The search may be based on previously developed information from which the location of the satellite can be predicted and, thus, limited to a small area of the sky, or cover a large area of the sky in accordance with a search routine. After the beacon of a satellite is acquired, the geographic area served by the satellite is determined. If the satellite does not serve the cell within which the ground terminal is located, a further satellite search is conducted, which may be based in part on information contained in the beacon of the acquired satellite. After the satellite serving the cell containing the ground terminal is acquired, a test is made to determine how long the satellite will continue to cover the cell.

Abstract: An apparatus and method for detecting an antenna mispointing condition of an earth station. A noise floor detector, coupled to a received radio communications link signal, measures a noise floor of a selected frequency band in which no radio signals are normally present. A controller, coupled to the noise detector, detects an antenna mispointing condition when a signal strength of the received radio communications link signal is less than a predetermined signal strength and a difference between the measured noise floor and a baseline noise floor measurement is less than a predetermined difference.

Abstract: An antenna having multiple antenna elements that are selectively activated performs an initial acquisition of a satellite signal by activating only a few of the antenna elements. This results in a broad beam width and increases the likelihood of detecting the signal from the satellite. When the satellite signal is initially detected, the system increases the number of active elements to narrow the beam width. The system incrementally increases the number of active antenna elements until the detected signal from the satellite exceeds a predetermined threshold. At that point, the location of the satellite may be precisely determined and all antenna elements activated to lock onto the satellite signal. If the antenna loses acquisition of the satellite signal, the reverse process may be implemented whereby some elements are selectively deactivated to broaden the beam width of the antenna in an effort to reacquire the satellite signal.

Abstract: A navigation/guidance system uses a dead reckoning navigator with periodic GPS fixes to correct the drift of the inertial system. The navigation system primarily uses speed sensed by Doppler radar and attitude and heading sensed by a set of gyros. The navigation system uses various processes to compensate for any sensor errors. The system uses attitude data to compensate for GPS leverarm errors. The system can be used on a land-based vehicle to economically and accurately provide navigation data.

Abstract: A digital spacecraft antenna tracking system and method are provided which utilize an array of antenna feed elements oriented relative to a shaped spacecraft reflector antenna system each of which generates an output signal corresponding to a received incident signal. The outputs can be processed by a mixer/multiplexer (M/MUX) before processing by a digital tracking control receiver. The direction of a beacon signal incident on the spacecraft reflector antenna system is obtained by the TCR by comparing the beacon response of the M/MUX to a set of premeasured responses to incident signals having a known direction or orientation relative to a reference tracking grid. The premeasured responses are stored in a memory as a set of reference responses. Once the direction of the signal is obtained, the TCR assigns control voltages which are used by the spacecraft to steer the spacecraft antenna to a desired pointing direction relative to the beacon signal.

Abstract: An apparatus for aligning an antenna, for example an antenna of home satellite receiver system, includes means for detecting a received signal strength of a signal received at the antenna. Coupled to the detecting means are means for generating a display signal indicative of the received signal strength. The means for generating are configured to provide a first display signal when the received signal strength is in first state and to provide a second display signal when the received signal strength is in second state. Coupled to the means for generating the display signal are means for displaying the display signal. The means for displaying are capable of responding to both the first display signal and the second display signal. The first display signal may be a signal having a frequency proportional to the received signal strength.

Abstract: In a cell of a microwave cellular video distribution system, e.g a multichannel video distribution system operating at frequencies of around 29 GHz or 40 GHz, the transmitting antenna is composed of individual antenna sectors (62a,62b,62c . . . ) for transmitting the microwave signal towards different sectors (216a,216b,216c . . . ) of the cell. In accordance with the present invention, a respective monitor (D,R) is present in each of the different sectors (216a,216b,216c . . . ) of each/the cell to monitor the microwave signal transmitted in that sector. The antenna sectors (62a,62b,62c . . . ) are individually fed through controllable feed means (59,60,61) which permit individual control of the power level of the microwave signals transmitted by the individual antenna sectors (62a,62b,62c . . . ), including the switching off of that sector. A feedback coupling (40,44,49) is present between each monitor (R,D) and the controllable feed means (59,60,61) of the respective antenna sector (62a,62b,62c . . .

Abstract: Desired positioning of a sensor, such as an antenna, is provided. The system includes a platform which can be a vehicle, such as an aircraft. The sensor is connected to the platform by means of a mount. Alignment data is obtained in order to compensate for any difference in reference coordinate systems between the platform and the mount when the platform is in a first position. The alignment data can be obtained by incremental scanning of the sensor relative to an object that transmits a signal to the sensor. The strengths or amplitudes of the signals at the incremental positions can be utilized in calculating or arriving at the alignment data used to compensate for any misalignments between the coordinate systems of the platform and the mount. When the movable platform is in another position, the alignment data is used to desirably position the sensor.

Abstract: Connector switch apparatus which can provide either a cable or satellite television signal or a ghost-free off-air television signal. The apparatus obtains the cable or satellite television signal from a cable or satellite tuner, which can be included in the apparatus; and includes a television tuning device for producing a ghost-free off-air television signal, and a switch which provides either of those signals. The television tuning device employs use of antenna directionality control and ghost cancellation to produce a ghost-free off-air television signal. In particular, the television tuning device obtains an off-air television signal from a antenna, which may or may not be included therein, whose directionality can be changed to change reception quality of a received off-air television signal; and includes a baseband ghost cancellation unit which can perform baseband ghost cancellation.

Abstract: A method and system for pointing a receiver antenna is described herein. The method includes providing an indicator, receiving a signal at the antenna over a series of positions throughout which the antenna is moved, measuring a signal strength of the signal at each position, and causing the indicator to emit an indication signal that reflects the signal strength at each position. The frequency of the indication signal preferably varies non-linearly to the signal strengths, and the difference between successive indication signal frequencies increases as said signal strength increases in order to allow an installer to more effectively perceive the variations in the frequency of the indication signal.

Abstract: A control portion performs gyro control at control intervals of .DELTA.t, by using -.omega.G, which is obtained by inverting the polarity of an angular rate .omega.G outputted from an angular rate sensor portion. On the other hand, a receiving level is detected at constant control intervals of .DELTA.T (=M.DELTA.t: M is an integer). The rotation of an antenna portion is controlled by using .omega.s, if the receiving level has increased, or by using -.omega.s, if the receiving level has decreased, i.e. by step track control. By accumulating the control amount .+-..omega.s for a predetermined long time period of N.DELTA.T, accumulation of an error contained in each angular rate .omega.G is obtained. The accumulated value is then divided by N to calculate an error .DELTA..omega.G contained in .omega.G. This error .DELTA..omega.G is used to compensate the actual error, so that the gyro control can be made more accurate.

Abstract: For power-optimised radio relay communication between in particular a station (11) which is operating at low level and navigating at high speed and which is fixed to a missile and a remote ground station (12) the apparatus and time expenditure for antenna tracking from the missile station (11) to the relay station (13) is reduced by the conventional production of an item of tracking direction information (17) on board the missile by direction-finding being replaced by computation of the directional information (17) from a comparison of the current locational data (15, 15') of the navigating station (11) and the relay station (13). If the position of the relay station (13) is variable its locational information (15') is also up-dated with satellite support, for example for correction of a reference position stored there it is transmitted to the missile station (11).

Abstract: In response to a position registration request transmitted from a mobile telephone terminal 1a (or 1b), at least one base station 2.sub.l (or 2.sub.N) selected by the mobile telephone terminal transmits a response signal to the mobile telephone terminal which measures a receiving electric field strength of the received response signal and a time between the transmission of the position registration request and the reception of the response signal. The mobile telephone terminal calculates a distance between it and the base station and a direction to the base station on the basis of the measured electric field strength and the measured time and displays the results of calculation. The mobile telephone terminal reports the results of calculation to a central controller 4 through the base station and a control station 3 to store it in a portion of a subscriber information memory 5 corresponding thereto.

Abstract: A passive locator and method for a wireless communication system. The locator (56) at base station (12) determines the position and trajectory of wireless terminal (22). The passive locator (56) adjusts azimuthal and elevational angles of a directional antenna (58) until a relative maximum power is detected in the signal transmitted from the wireless terminal (22). A processing circuit (60) determines the trajectory of the wireless terminal (22) by generating and analyzing data that represents the Doppler effect on the signal from the wireless terminal (22).

Abstract: A fixed terminal forms a highly directed beam toward a satellite and adaptively maintains a beam to track the satellite as the satellite moves relative to the fixed terminal. The fixed terminal includes a database that contains the positional information of all potential communication satellites. The fixed terminal antenna system provides for both simple auto-steering on installation for ease of use and terminal access to multiple satellite services. The proximity detector detects objects that may interfere with the antenna beam. The proximity detector includes infrared sensors, sonar detectors, motion detectors and optical devices to determine a range and bearing of objects that may interfere with the antenna beam. When an object may be harmed or interfere with the antenna beam, an alarm may be activated to warn the user and/or the object of potential harm from the electromagnetic energy transmitted by the directed antenna.

Abstract: A method and apparatus for utilizing satellite update information are disclosed. In the preferred embodiment satellite update information, comprising satellite position, polarity, name, and abbreviation, are accumulated at a first location and transmitted via satellite to at least one of a plurality of satellite receivers. The satellite receiver is operable to receive and automatically utilize the satellite update information such that the end user of the satellite receiver in unaware of the automated process of updating satellite information in the satellite receiver. The satellite receiver uses a portion of the satellite update information to calculate a pulse count for positioning an antenna to receive radio signals from a satellite for which satellite update information has been received.

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: An autotracking antenna system operable to cause a steerable antenna assembly to automatically track a moving RF video signal source has a reflector, a rotator for positioning the reflector at any desired position in azimuth and elevation, a primary antenna element positioned to receive an RF video signal reflected from the center of the reflector, and a series of offset antenna elements each positioned to receive an RF video signal reflected from a different off-center location on the reflector. A tracking control processor is operable to select and receive video signals from the primary antenna element and the offset antenna elements and to control the rotator, and a signal receiver receives video signals from the antenna element and has a video signal output.

Abstract: An optical antenna pointing controller for an optical antenna system having an optical antenna and biaxial gimbal mechanism coupled to the optical antenna and mounted on the satellite is provided. Feedback control in the controller is gain-stabilized by a nominal compensator, and disturbance is suppressed by a robust compensator, further, a target satellite is captured quickly with the aid of a reference model and feedforward, thus providing quick response without dependency on the band width of feedback control system.

Abstract: A mobile satellite communication system includes an antenna assembly mountable on a vehicle and a satellite tracking assembly. The antenna assembly includes an antenna device for receiving first satellite signals from a first satellite in a first frequency band and for transmitting and receiving second satellite signals to and from a second satellite in a second frequency band, and a drive subassembly for rotating the antenna device relative to the vehicle in response to a control signal. The satellite tracking assembly maintains the antenna device pointed at the first and second satellites as the vehicle moves. The system further includes a receiver coupled to the antenna device for receiving the first satellite signals and a transceiver coupled to the antenna device for transmitting and receiving the second satellite signals. The first satellite signals may be video and imagery data signals transmitted in the Ku band by a direct broadcast satellite.

Abstract: An adaptive antenna array 104 is disclosed. The adaptive antenna array 104 includes a plurality of reflector elements 202 and an array control processor 208 that regulates several resolvers 209, 210, 211 to generate independent magnetic fields. The array control processor 208 also generates reflector element command and control information and transmits the command and control information with a transmitter 218 to the reflector elements 202. The reflector elements 202 include a detector 706 that detects the transmitted command and control information. The reflector elements 202 further include a signal reflector 308 that reflect incident RF energy, a magnetic transceiver 310, and a reflector element controller 314. The reflector element controller 314 is connected to the detector 706 and interprets the command and control information 402.

Abstract: A point-to-multipoint radio broadcast communication system comprises a directional transmitter focused on a particular one of a plurality of receivers in a linear arrangement, such that the angle between each successively closer receiver and the transmitted beam increases as the distance between the transmitter/receiver pair decreases. Thus, a low-power directional transmitter can effectively transmit to a line of receivers due to the trade-off between a receiver being off-center and its closer proximity to the transmitter.

Abstract: In a vehicle mounted satellite signal receiving apparatus which adopts a satellite tracking system combining a gyro tracking with a hybrid tracking, there is provided a device which can revise an offset error correction value of a gyro sensor, even if there is a drift in the offset error. In this device, gyro tracking is performed when a reception level is a threshold value L.sub.C or more. The gyro tracking is performed by setting an antenna at an angular velocity .omega., which is derived from an equation,.omega.=-.omega.G+.DELTA..omega.G, where -.omega.G is a value resulted from conversion of sign for gyro angular velocity .omega.G, and .DELTA..omega.G is a prescribed offset error correction value. A reception level declines if the offset error correction value .DELTA..omega.G deviates and therefore an apparent offset error arises in the gyro sensor. When the reception level declines below a threshold value L.sub.B, the aforementioned offset error correction value .DELTA..omega.

Abstract: A wireless transmitter and receiver are used in a wireless telecommunication system and method including antennas having at least one antenna element with a relatively narrow beamwidth at both the transmitter and receiver for high data rate communication. The antenna element provides beam coverage in both azimuthal and elevational directions, and a processor is operatively connected to the antenna and is capable of determining a suitable communication path with respect to the at least one antenna element and predetermined communications conditions.

Abstract: A new and improved system which facilitates the use of sunlight and sun shadows to optimize site surveys and the placement of satellite dish antennas and the like in order to provide unobstructive reception from a satellite transmitter and, further, facilitate alignment of the dish relative to a satellite.

Abstract: A method and device for aligning a satellite receiver antenna with a broadcast satellite is disclosed herein. The device includes a receiver for measuring a signal strength from the satellite and issuing commands based on the measurement, a receiver antenna capable of automatically changing its alignment, and a rough alignment indicator located remotely from the receiver for signalling when the antenna is pointed sufficiently toward the satellite allow the receiver to maximize the signal strength by aligning the antenna with the satellite via commands from the receiver. The method includes placing the receiver antenna on a stable surface, manually pointing the antenna in the direction of the satellite until an indicator signals that the antenna is preliminarily aligned, fixing the receiver antenna to the stable surface, and activating a device remote from the antenna to automatically perform final alignment of the antenna with the satellite.

Abstract: In order to determine the direction of a beam antenna, at least one magnetic detection device is attached to the beam antenna for measuring at least one of the horizontal and vertical components of the geomagnetic field. Maximum and minimum geomagnetic field data values are obtained from the magnetic detection devices while rotating the beam antenna. Based on output data from the at least one magnetic detection means, one or two possible direction candidates are determined. When the output data has only one possible direction candidate it is either a maximum or minimum value. The direction of the beam antenna is determined from the two direction candidates by specifying one of the candidates depending upon whether a direction of the beam antenna is to the right or left, and determining the direction of the beam antenna from one direction candidate when the output data from the at least one magnetic detection devices corresponds to the minimum or maximum geomagnetic field data.

Abstract: A system for the control of the orientation and configuration of an indoor TV antenna. Such control can be effected by using an infrared remote control device, such as the type conventionally used as a TV remote control, which controls the antenna directly. Alternatively, optimum antenna orientation and configuration can be determined for each channel and stored in a memory and, when the viewer selects a particular channel, the antenna is automatically adjusted to the stored optimum orientation and configuration associated with that channel. Some of the antenna characteristics which can be controlled and stored include the orientation of antenna elements about a vertical axis, the length of the elements, the relative angle between elements, the angular orientation of a loop antenna about a vertical axis, the angular orientation of a loop antenna about a horizontal axis, the diameter of the loop antenna, and other attributes such as antenna amplifier gain.

Abstract: A setting apparatus of an antenna for satellite broadcasting in a satellite broadcasting system includes a receiving device coated with a fluorescent material whose color varies depending on a level of a voltage applied thereto, for receiving a satellite broadcast signal; and a controlling unit coupled to the receiving device for applying a driving power source to the fluorescent material of the receiving device, depending on a level of the satellite broadcast signal received in the receiving device.

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 method and apparatus for aiming a satellite dish includes an adjustable gnomon. The adjustable gnomon is calibrated. Using setting information generated by computer softwvare, a user sets the gnomon according to the calibration numbers returned by the computer software. The user then lock the setting into place. After locking the gnomon into position, the user employs the gnomon to aim a satellite dish or other directional antenna. Aiming the antenna requires aligning the antenna such that a shadow cast by the gnomon substantially coincides with a predetermined target.

Abstract: It is the object of the present invention to provide a fixed earth station in which many antennas can be placed in a site area limited to one-several tenth of the conventional one.On a rotatable base 2, a plurality of antennas 1a to 1e are mounted. A control unit 4 controls the rotation angle of a drive unit for driving the base by the previously known orbital parameters of communication satellites. Further, the azimuth angle and the elevation angle of the respective antennas are controlled by antenna control units 5a to 5e, and the antennas catch and track communication satellites having appeared in the sky. As a result, the rotation angle of the base 2 can be set so that a beam accessing a satellite of a low elevation angle is not intercepted by other antennas. In addition, the area in which the antennas are placed can be reduced to about 1/50 of the conventional one.

Abstract: An adaptive receiving antenna reduces interference arriving in the main beam of the antenna by redirecting the antenna beam away from the interference source. The receiving antenna projects the main beam to receive desired source signals from a source direction and may receive interfering signals from the interfering source. The antenna system measures the strength of the source signal and interference signal for controlling the direction of the main beam to marginally decrease the received desired source signal while substantially decreasing the received interfering signal to increase the desired source signal to interfering signal ratio so that the desired source signal can be received in the presence of interference.

Abstract: A tracking antenna for non-geostationary satellites is mounted on a three-axis positioner comprising an azimuth axis, an elevation axis mounted perpendicularly on the azimuth axis and a pseudo-azimuth axis mounted perpendicularly on the elevation axis and supporting the antenna. The positions of the axes are controlled by a pointing unit. The method of pointing the antenna carries out the following steps simultaneously when the position of the satellite is such that the elevation axis exceeds a predetermined elevation value: modifying the position of the azimuth axis at constant speed and modifying the position of the elevation axis and the pseudo-azimuth axis to track the satellite.

Abstract: A method and apparatus for pointing a tracking antenna to a communication satellite in the initial stage of satellite tracking by means of frequency shifting, upon reception of a carrier wave having deviation from the accepted standards of frequency, the antenna initial pointing apparatus including a downconverter for converting a signal received at a directive antenna to an IF signal, a synthesizer for providing the downconverter with a local signal for the IF signal conversion, a power detector for detecting the power of the IF signal, and a controller for controlling the synthesizer to generate the local signal and also for controlling the rotation of the directtive antenna. Based on a detected result from the power detector, a downconverted IF signal having deviation from the accepted standards of frequency is further converted to be included within a limited bandwidth of the power detector by means of frequency shifting.

Abstract: A control method of the direction of directivity of a base station antenna in a mobile communication system which uses a variable directivity antenna at the base station. The direction of directivity is controlled to continuously change such that signal reception level at each mobile station exceeds a prescribed value during the time interval from the beginning of the first slot to the end of the (n+1)th slot of any continuous n+1 (n being a natural number) slots on at least one time-division-multiplexed channel.

Abstract: A relative GPS landing system is provided for approach and landing of aircraft where an accurate site survey of the GPS platform is unavailable. Data containing information on all GPS satellites in view is uplinked from a ground station to an aircraft. A relative solution is derived at the aircraft. Based upon the calculated solution, aircraft guidance signals are generated for approach and landing of the aircraft at a desired point.

Abstract: A mobile receiver for satellite broadcast comprises directive antennas, a navigation unit for generating a navigation signal representing a position and an attitude of an airplane, a control unit for generating a control signal for controlling the antennas, on the basis of the navigation signal from the navigation unit and prestored information indicating a position of a broadcasting satellite, and a drive unit for driving the antennas in response to the antenna control signal from the control unit to orient the directivity of the antennas toward the broadcasting satellite.

Abstract: An apparatus is disclosed which computes the full-step number of full-step drive pulses at each control period, generates microstep drive pulses on the basis of the full step number so as to make a drive angle at each control period correspond to a full-step unit, and drives a motor drive current on the basis of the microstep drive pulses.

Abstract: An antenna tracking control device includes detectors for detecting speed and the steering angle of a movable body, a device for calculating the estimated azimuth angle of the movable body based on the detected speed and steering angle, and a detector for detecting the azimuth angle of the movable body. Also, an azimuth angle error estimator is provided for calculating the error between the calculated estimated azimuth angle and the detected azimuth angle. In addition, a directing angle error detector is used for detecting antenna directing angle error, and a directing angle error corrector is used for correcting the detected antenna directing angle error, with the result that the antenna tracking control device causes an antenna mounted on a moveable body, such as an automobile, to track a wave generating source based on the corrected antenna directing angle error.