Abstract: A terrain awareness system (TAS) provides LOOK-AHEAD/LOOK-DOWN as well as LOOK-UP terrain advisory and warning indications to the pilot of an aircraft of a hazardous flight condition. The TAS includes an airport data base as well as a terrain data base that is structured to provide various resolutions depending on the topography of the particular geographic area of interest. Navigational data from a satellite-based navigational system, such as a global positioning system (GPS), is used to provide a LOOK-AHEAD/LOOK-DOWN and LOOK-UP terrain advisory and terrain warning indications based upon the current position and projected flight path of the aircraft. Since the terrain advisory and the warning signals are a function of the flight path of the aircraft, nuisance warnings are minimized.

Abstract: The navigation system has a display for displaying vehicle service reminders and an input device to permit the driver to define vehicle service intervals. A wheel speed sensor continuously inputs distance data into a CPU. A GPS system receiver continuously inputs date and time data into the CPU. The CPU compares the time and distance data to user defined vehicle service intervals. When the time or distance have exceeded the user defined vehicle service intervals, the CPU generates a vehicle service reminder on the display. The driver can then request the navigation system to guide the driver to an appropriate vehicle service location.

Abstract: A spacecraft (10) has an attitude sensor (20) mounted on its body (12). The sensor must be maintained near a temperature setpoint. Each sensor (20) produces its own temperature-indicative signal. Each attitude sensor is coupled to a thermally conductive instrument platform (18). A standoff (21) supports the platform (18) away from a baseplate (16) and the spacecraft body (12). The standoff (21) includes a thermally conductive portion (22) adjacent the platform (18), and a nonconductive portion (24) remote from the platform. An electric heater (26) is connected to the thermally conductive portion (22) of the standoff (21). A temperature sensor (28) thermally coupled to the platform (18) generates platform temperature signals. A filter (212) high-pass filters either the platform temperature signals or the attitude sensor temperature signals, to form filtered signals. A combining circuit (218) combines the filtered signals with the other temperature signals, to make composite temperature signals.

Abstract: The present invention relates to a method for three-dimensional flight control based generally upon measuring and comparing actual air pressures at or near various surfaces of an aircraft during flight. Sensors are provided for measuring air pressure acting on the aircraft surface. The method includes measuring air pressure differentials between two or more sensors to evaluate certain critical flight parameters, such as the actual lift being produced, the air direction and speed relative to the aircraft, the air density, and the aircraft position and trajectory. The actual and comparative data provide information about the present flight conditions and performance if the aircraft, such as whether there is ice formed or forming on the wings, the direction and approach of wind shear, whether a stall is approaching, etc. The information can be evaluated by a computer, the aircraft's automatic flight control system ("AFCS"), or flight crew so that appropriate flight control measures can be taken.

Abstract: A voice route-guidance system for vehicles which terminates its route-guidance when the vehicle arrives at the destination and even if the present position of the vehicle is measured with low accuracy. An approach judging unit judges that the vehicle approaches a point spaced apart from a destination by a predetermined distance. A guidance termination judging unit further judges whether or not there is a point in which the route-guidance should be carried out between the present vehicle position and the destination. From these judgments, the system judges that the vehicle approaches the point spaced apart from the destination by the predetermined distance and also that all the route-guidance has been terminated. Thus, a termination unit terminates the route-guidance.

Abstract: The apparatus is an earth horizon crossing indicator used in a spacecraft attitude control system, which uses power from a self-contained battery rather than power from the spacecraft electrical system. The battery is typically of the lithium thionyl chloride type. This reduces the weight and complexity of the spacecraft attitude control system and allows the resources of the spacecraft electrical system to be used for other devices.

Abstract: A method of recovering the heading of a terrestrial vehicle navigation system having a GPS receiver integrated with a dead reckoning system. After determining that a current estimate of the heading may be in error (12, 14), Doppler measurement double difference observables are computed for all GPS satellites whose L band carriers are in phase or frequency track, available distance traveled and heading change information is extracted, and the results are combined and processed (20) to produce a new current heading estimate. A recursive estimator is used to guarantee convergence to an accurate result. Conventional GPS/dead reckoning combined systems generally reset to the first available GPS position following a heading loss. Gross positioning errors can accumulate up to this point, however. The methods described can recover the dead reckoning system heading by processing Doppler information from a single GPS satellite, and thus reduce position error growth occurring when the heading is unknown.

Abstract: A navigation apparatus displays a present position and an advance direction of a movable body on map information including road position information, and includes a measuring device for detecting a travelling distance and the advance direction and periodically measuring an advanced position, to update the present position.

Abstract: An apparatus for measuring the lift generated by airfoils of an aircraft. This real-time analysis is accomplished by measuring a differential pressure between the upper and lower lift surfaces of the airfoils. The apparatus a) measures an actual differential pressure between the upper and lower lift surfaces for a given aircraft speed, b) transmits this actual differential pressure measurement to a computer, c) compares the actual differential pressure measurement with an optimal pressure differential for the same aircraft speed, and d) evaluates performance of the aircraft based on the result of the comparison. The apparatus comprises a fixed array of differential pressure sensor mechanisms for measuring actual pressure differentials and a computer for comparing optimal differential pressure measurements to the actual differential pressure measurements. Each sensor mechanism preferably contains a piezoelectric sensor that communicates with the upper and lower lift surfaces.

Abstract: A method of land vehicle suspension evaluation and design through roll angle analysis. The method is based on predicting front roll angle and rear roll angle for a given road bank angle and lateral vehicle force. Method steps include determining a vehicle front section sprung weight, determining a vehicle rear section sprung weight, predicting a front roll angle, predicting a rear roll angle, comparing the predicted front roll angle XXXX to the predicted rear roll angle, and changing suspension components XXXXXXXX until the predicted front roll angle equals the predicted rear roll angle. Benefits associated with equalizing the front and rear roll angles include improved vehicle stability, increased total vehicle tractive capacity, and better handling.

Abstract: A vehicle navigation system. A road map is displayed on a screen. The present position of the vehicle is displayed on the road map displayed on the screen. A guide route connecting a start point of the vehicle and a destination of the vehicle which are set in advance is determined, and indicated on the road map. A return route for returning the vehicle to the guide route is selected in response to a deviation of the vehicle from the guide route. A cost required for the vehicle to return to the guide route via the return route is calculated, and the vehicle is prevented from entering the return route depending on the cost calculated.

Abstract: The disclosed optoelectronic device is designed to facilitate the piloting of an aircraft under conditions of poor visibility, notably during landing at the stage when the aircraft approaches a runway. It consists of a collimator which displays, in addition to the artificial skyline, miniature aircraft index and attitude bars, a slope scale positioned across and on either side of the artificial skyline, at the position of the selected course chosen by the pilot. This slope scale, depicted in the form of a line of dots spaced out at one slope degree, enables the pilot to be presented simultaneously with information on selected course and slope and enables the determining of pitch attitude with high precision.

Abstract: A navigation apparatus which includes an input section, a central processing section, a display section and a memory section is mounted on a moving object. When an initial or current position and destination of the moving object are provided to the central processing section, the apparatus produces two or more possible routes along which the moving object can move to reach the destination after starting from the current position by using map data stored in the memory section. The initial or current position, destination and possible routes are repeatedly calculated, updated and indicated on a screen of the display section. The two or more possible routes are repeatedly produced by a processor and calculation/retrieval circuitry. A connection route existing between the two or more possible routes may be retrieved and repeatedly indicated. Furthermore, a possible area containing the possible routes may be retrieved and repeatedly indicated.

Abstract: The object location identification system includes a Receiving Module (RM), an Angular Measuring System (AMS) and a processor. The RM receives information specifying a user's location and provides RM output data in terms of latitude, longitude and altitude. The AMS is connectable to a pointing device for measuring the orientation of the pointing device and providing AMS output data in at least heading and depression angles. The processor processes the RM output data and the AMS output data and provides location data of an object being pointed at by the pointing device.

Abstract: This device can record descent data for successive skydiving jumps with a pressure transducer for providing a pressure signal signifying ambient pressure. The device also has a processor coupled to the pressure transducer for displaying descent data on a display. The processor has a triggering routine and a recording routine. The triggering routine can provide a trigger signal in response to predetermined changes in the pressure signal from the pressure transducer. The recording routine can record for each jump in response to the trigger signal, a datum corresponding to the pressure signal. Each datum is held for at least a predetermined number of succeeding jumps. A temperature sensor coupled to the processor can provide a temperature signal signifying ambient temperature. The processor can display through the display, altitude signals derived from the pressure signal and adjusted by the temperature signal.

Abstract: A new aircraft cockpit instrument panel display system for showing the operating status of different aircraft systems is disclosed. The color display includes a plurality of display segments. Each display segment combines trend qualitative information of the direction of movement of aircraft system parameters, categorical qualitative information of whether aircraft system parameters are inside or outside acceptable ranges, and quantitative information of the actual level of aircraft system parameters. Trend information is indicated by an analog dial display element having a moving needle to indicate rising, falling or constant values of the parameter. The dial display also includes peg positions to indicate that the value of a system parameter has "pegged" at its lowest or highest value. Categorical qualitative information is indicated by the color of the dial, generally green for safe values, yellow for cautionary values and red for danger values. Quantitative information is indicated by a digital indicator.

Abstract: A vehicle navigation system displays arrow icons to a driver indicating the directions he must follow from each of one or more turning points on his route to keep the driver from passing inadvertently an intersection in which he must change the vehicle's direction of advance or from turning in an intersection prior to the intersection previously chosen for a turn. Road anomalies, such as sharp curves or U turns are also displayed. The arrow icons are alternatively created from computed directions of the vehicle's advance or stored in an X-Y storage unit from which an arrow icon best fitting the required guidance is selected. The stored arrow icons include straight road, single turns, and multiple turns. The selected arrow is displayed to the driver. An embodiment calculates turns and curves with angles which match the actual angles of the turns, and radii and turning angles of curves.

Abstract: The invention is a method for determining anemobaroclinometric parameters on board an aircraft.The air speed vector (Vp), the static pressure (Ps), and the impact temperature (Ti)are measured, and the other parameters are calculated on the basis of the aforementioned measurements.

Abstract: A vehicle navigation system for a vehicle operable by an operator includes a memory for storing data representing a road map including roads and their junctions over which the vehicle can travel as well as a number of available routes over the roads; a display and processing device for some of the data; a light pen device for following map data displayed on the display device to selected a desired route for vehicle travel, not necessarily one of the stored available routes; an input device for storing the desired route selected by operation of the light pen device; a correlation device for comparing the desired route stored in the input device with the available routes in memory to find a selected route which is closest to the desired route; an additional memory for storing the selected route connected to the correlation device; and a control unit connected to the additional memory for displaying and/or communicating the selected route to the operator.

Abstract: An orientation monitoring apparatus includes an inner spherical shell rigidly fixed within an outer spherical shell, and a spherical ball positioned between the two shells. The inner shell has a polar coordinate grid impressed on it so that the position of the ball relative to the grid is seen from above. An inertial platform is rotationally interfaced with the inner shell. This platform supports a video camera with a view of the grid and ball. As well, the platform supports a motor driven fly-wheel which keeps the platform in a desired horizontal attitude. The motor, camera and a computer are driven by a solar cell and storage battery also mounted onto the platform and which receives energy through the transparent shells. An optical recognition software driven by the computer, is used to automatically compute the movements of the ball relative to the grid so that rotational movements of the shells can be computed in three-space.

Abstract: A guide system for a vehicle includes guide data storage containing guide data for conversion into output information concerning guidance objects along roads to be travelled by the vehicle and in the general area thereof. A TV monitor and microphone serve to output the information. A present position detector detects the present position which is traced on a map display output on the TV monitor. A first search routine searches over a first area range for guidance objects on the basis of the detected present position and a second search routine searches for guidance objects over a second area range different from the first area range. Once a guidance object is located, the guide data for that located guidance object is read out from the guide data storage and converted into output information. A manual key is provided on a remote controller for switching to the second search routine.

Abstract: A system (400) for positioning and navigating an autonomous vehicle (310) allows the vehicle (310) to travel between locations. Position information (432) is derived from global positioning system satellites (200, 202, 204, and 206) or other sources (624) when the satellites (200, 202, 204, and 206) are not in the view of the vehicle (310). Navigation of the vehicle (310) is obtained using the position information (432), route information (414), obstacle detection and avoidance data (416), and on board vehicle data (908 and 910).

Abstract: A shock generating position storage unit includes an acceleration sensor for detecting an impulsive wave or shock applied to a vehicle during transportation thereof, a storage unit for storing data representative of such impulsive wave or shock, and a global positioning system (GPS) for determining a position of the vehicle along a travel path based on a radio wave received from an artificial satellite. Data of the travel position at a time when data of the impulsive wave or shock detected by the acceleration sensor exceeds a predetermined minimum value is sent to the storage unit from the GPS at the same time the impulsive wave or shock data is sent thereto.

Abstract: A small and inexpensive bearing-distance sensor capable of detecting a travel bearing and a travel distance of a vehicle. The bearing-distance sensor includes a rectangular parallelepiped case. A first acceleration sensor and a second acceleration sensor are mounted within the case. The first acceleration sensor detects an acceleration in a first direction, e.g. the longitudinal direction of the case, to obtain a signal related to the acceleration, and the second acceleration sensor detects a force applied in the width direction of the case, which is perpendicular to the first direction, to obtain a signal related to that force. The travel distance of the vehicle is found from the output signal of the first acceleration sensor, and the travel bearing of the vehicle is found from the output signals of the first and second acceleration sensors.

Abstract: A method and apparatus for minimizing the effect of lateral velocity transients upon an aircraft inertial instrument calibration process of the type in which cross-track velocity is measured and utilized to correct for the east component of gyro bias error. A "cross-track position" value is obtained by integration of the cross-track velocity. A Kalman filter calculates a plurality of gain values corresponding to measurements of crab angle, lever arm, north and east velocity, heading angle and rate of change of heading angle and those gain values are applied to the cross-track position value to obtain error values for each of such parameters. The calculated error values are then employed as corrections to, or calibrations of, the inertial instrument outputs.

Abstract: A method and apparatus for navigation of a vehicle travelling over a terrain in which the changes in elevation of the vehicle are continuously measured, in addition to the distance and heading. The distance measurements are continuously corrected by the changes in elevation in determining the instantaneous location of the vehicle with respect to a known point. The approximate location can also be obtained from a satellite GPS (global positioning system). The measured elevation may also be compared with the elevation in reference data, such as data in a three-dimensional map of the area to prevent the accumulation of errors or to make the determined location more precise.

Abstract: A map management system in a geographic information management system which manages different kinds of maps with use of a computer. The map management system involves a map managing unit that prepares map databases for respective attributes, manages the databases, and allocates the attributes in accordance with an access right for the databases. A map processor accesses the databases through the map managing unit, retrieves necessary data from the databases, and displays the data. Different kinds of maps are separately stored in separate databases so that each map is separately retrievable. Several kinds of maps can be simultaneously retrieved. An access right is allocated for each of the separate databases depending on the importance of the attributes. According to the access right for a given database, the map managing unit determines whether data contained in the database is displayable, or displayable and correctable.

Abstract: A navigation system for a vehicle enables an operator to know a calculated optimal path from a starting point to a destination before departure. After the optimal path is calculated, a preview function allows the operator to sequentially view the calculated optimal path either prior to departure or at any point along the optimal path. A cancel function allows the operator to cancel a displayed portion of the optimal path and to request calculation and display of an alternate optimal path which does not employ the canceled portion of the original optimal path.

Abstract: A method for monitoring the movement of a vehicle along a selected route R to determine whether the vehicle is (i) adhering to that route and/or (ii) adhering to a selected time schedule along that route. Adherence to the route R requires that the vehicle travel within a corridor of selected positive width that surrounds a path defining the route R. Adherence to the time schedule requires that the vehicle move past one or more specified locations along or adjacent to the route R within a specified time interval. The method provides an electronic map with a visually perceptible display that indicates the present location of the vehicle and allows implementation of a snap-to-route command that displays the location on the route R that is closest to the present location of the vehicle.

Abstract: In order to study the aerodynamic phenomena occurring around structures of an aircraft, particularly during ground and flight tests, an automated multichannel pressure measuring system is proposed. This system, which is entirely contained in a very small box or case (10), incorporates the pressure transducers (14) and processing software (54) for the approximate values supplied by the transducers. A multichannel or multiway valve (32) places the system in a blowing or blasting state purging the circuits in the case or rain. In this state, it is possible to check the satisfactory operation of the transducers and carry out their calibration. Therefore, the frequency with which recalibration of the system has to take place in the laboratory is greatly reduced. Advantageously, the transducers (14) are temperature-controlled.

Abstract: A storage medium for map information for a navigation system includes an IC memory chip or an IC memory card of a small memory capacity. This storage medium stores detailed map information of a limited region including part of a highway network and information of the highway network covering a predetermined area which includes the limited region and is wider than the limited region. A system for offering map information for a navigation system includes two storage media. One storage medium is the same as the above-mentioned storage medium and the other storage medium has a small memory capacity. The other storage medium stores detailed map information of a limited region different from the limited region whose information is stored in the one storage medium.

Abstract: Vehicle navigation apparatus (10) calculates an initial route to a destination (52) via connected road segments (55, 59) defined in a road map data base. In response to a can't do-reroute signal, indicative of the vehicle user determining unsuitability of following the initial route guidance instructions, a new route (55, 60, 61, 62, 59) to the destination is provided. Automatically excluded from the,new route is a maneuver (ordered road segment pair (55-59)) and/or a road segment of the initial route. This prevents the new route from including an initial guidance instruction which was determined as unsuitable. Also, calculated routes are provided by calculating the route from a predicated position of the vehicle at a subsequent time based on the vehicle's current position, direction and rate of travel. This ensures that when the route is provided at the subsequent time, the vehicle will not have passed the first maneuver to be implemented in the calculated route.

Abstract: The invention provides a route state filter for a vehicle route guidance system for improved tracking of vehicle position with respect to a preselected route. A set of position possibilities are derived by comparing a measured vehicle position to a database containing data representing a map of roads, the possibilities corresponding to possible positions on the roads within an error region around the measured position. A route guidance module receives the position possibilities, checks their validity and applies a filter to remove less likely possibilities. A current position is then selected from the remaining possibilities. An ON/OFF ROUTE status of the vehicle is determined by comparing the selected position with the selected route information in the database. A distance-based filter is utilized to provide improved continuity in the route status determination.

Abstract: A route connecting a point and another point on a network is derived in advance with respect to entire pairs of two points, and the route is stored with a transit point placed on the route in a memory. When a route between two points is retrieved, the route is divided by the transit point, and a route in each division is retrieved. Subsequently, plural routes of the divisions are connected and thus the route between the two points is derived.

Abstract: A speed indicator for marine vehicles is mounted on the lower transom area of such a vehicle and includes an impeller. The impeller rotates at an angular velocity dependant on the speed of marine vehicle relative to the water. A mounting bracket secures the speed indicator to the marine vehicle in a manner to permit movement of speed indicator relative to the marine vehicle so that the axis of the impeller remains generally in line with the direction of travel of the marine vehicle. To try to ensure laminar flow across the impeller and to facilitate movement of the speed indicator, the speed indicator has a guide vane positioned upstream of the impeller. The mounting bracket also permits adjustment of the speed indicator so that the axis of the impeller is basically parallel to the plane of the bottom of the marine vehicle. A sensor including a magnetic conductor and a magnetic pick-up detects rotation of the impeller and generates output representative of the speed of the marine vehicle.

Abstract: A motor vehicle-mounted navigation apparatus comprising an input section adapted for inputting data based on GPS positioning, an azimuth sensor and distance sensor adapted for establishing independent navigation signal input sections for inputting data relating to a present position of motor vehicle and an azimuth thereof based on self-determining type navigation. The motor vehicle-mounted navigation apparatus further includes a control unit for determining the present position of the motor vehicle based on the obtained data through the input sections as described above, whereby error correction for the azimuth sensor is implemented by feeding back an output signal the control unit.

Abstract: The Driver's Associate assists a driver of a vehicle to more efficiently reach a desired destination, to record the route driven, and to provide driving summary reports. The present invention uses a unique method for tracking the dead-reckoned coordinate of the vehicle by using a sum-of-squares or .chi..sup.2 minimization algorithm for plotting the navigation route, tracking the vehicle through the road map database, and for normalizing the vehicle's location between the dead-reckoned coordinate and the roadway projected coordinate. The present invention also uses a Singular Value Decomposition method for optimizing the normalization process so that we can track a vehicle's location more accurately than other navigation devices.

Abstract: A correct vehicle position is detected even when the road data to be used in the map match computation includes errors of partial shape. When the matching computing operation of a running locus and the road data obtained from the outputs of a bearing sensor and a distance sensor and a non-match region has been effected by the map match computing means, the non-matching region of the road data and the running locus is detected. The positional error detection caused by errors of the road data is effected by prohibiting map integration.

Abstract: An onboard flight management system produces cost-effective trajectory target signals in response to an input desired time of arrival. Aircraft monitoring systems produce signals corresponding to real-time aircraft parameters including fuel flow rate, airspeed, windspeed, thrust, drag and mass. Stored in memory are aircraft characteristics including time cost, fuel cost, and acceleration due to gravity. A flight computer responds to an input desired time-of-arrival and the real-time parameters and stored characteristics signals and produces cost-effective trajectory target signals. The computer employs multiply regressed drag and fuel flow models which avoid trajectory discontinuities and the trajectory targets are produced using a Fibonacci search technique, which is computationally very efficient.

Abstract: A GPS receiver comprises a data input/output port for communication of datum-less position fixes in an earth-centered, earth-fixed (ECEF) coordinate style to avoid the errors associated with not communicating the datum choice with latitude longitude data communication formats.

Abstract: A method for navigating an aircraft around the earth's polar region comprises the steps of determining if the aircraft is in one of the polar regions of the earth's traditional axis system. If the aircraft is not in one of the polar regions, aircraft parameters, including speed and heading, are calculated relative to the traditional axis system. If the aircraft is in one of the polar regions the traditional axis system is rotated to form a new axis system, such that the aircraft position in the new axis system is in an essentially rectilinear area of the new axis system. The aircraft parameters are transformed, including aircraft position, speed, and heading, into parameters relative to the new axis system. New parameters are calculated with respect to the new axis system, and then the new parameters are translated into parameters with respect to the earth's traditional axis system.

Abstract: The piloting assistance method embodying the invention consists in displaying on a screen of the cockpit of the aerodyne, in a Cartesian reference space representing altitude/distance from ground along a horizontal plane, way points identified by a series of marks, plural way points, a reference vertical profile connecting the way points by connecting lines and altitude constraint symbols indicating a minimum altitude at which the aerodyne can pass, a maximum altitude at which the aerodyne can pass and an altitude at which the aerodyne must necessarily pass, a symbol indicating the position of the aerodyne. The invention enables the pilot to have a clear vision of the vertical situation of the aerodyne along its flight plan.

Abstract: The present invention includes a system for estimating the terrestrial position of a vehicle. The system receives electromagnetic signals from a plurality of sources and responsively producing respective ranges from each of said sources to said vehicle and respective positions of each of said sources. The system projects the position of one of said sources to the opposite side of the Earth and responsively determining a projected position and a projected range. The vehicle's position is determined as a function of said ranges and positions.

Abstract: An on-board navigation apparatus in which one of a plurality of service facilities displayed on a display is designated by an operator input, the position coordinate data corresponding to the designated one service facility is registered as a user position into a memory. When the map is displayed on the display, the position coordinate data which has been user position registered is read out from the memory. The position on the map indicated by the position coordinate data is multiplexed onto the map by a predetermined pattern and displayed on the display. The positions of the service facilities such as restaurants, hotels, or the like, which are necessary for each user, consequently, can be easily confirmed on the displayed map.

Abstract: A navigation apparatus is provided with a measurement device for measuring a present position of a movable body, and memory device for storing map data and a map matching device. The map matching device performs map matching on the basis of the present position data and the map data to obtain a plurality of present position candidacies and select a most reliable present position candidacy as a map matched present position among the present position candidacies, and updates present position display data indicating the map matched present position. The navigation apparatus is also provided with a display unit for displaying the map matched present position on a map and for displaying a travelling locus of the movable body on the basis of a plurality of present position display data updated in the past.

Abstract: The invention is a process and a device for determining an estimation of the altitude of an aircraft from at least two independent measurements of the altitude, by polling. The aircraft must include at least one inertial reference system. A signal representing a first or second derivative of the altitude is diverted from the inertial reference system, polling is undertaken on the magnitudes of like order deduced from the independent altitude measurements and from the derivative of the altitude, respectively, and an integration operation is undertaken so as to obtain the altitude estimation.

Abstract: An embodiment of the present invention is a combined GPS and dead-reckoning (DR) navigation sensor for a vehicle in which a pair of modifications are made to an otherwise conventional Kalman filter. Process noise is adapted to cope with scale factor errors associated with odometer and turning rate sensors, and correlated measurement error processing is added. When only two Doppler measurements (PRRs), or three with an awkward three-satellite geometry, are available, DR error growth can nevertheless be controlled. The measurement error correlations in the conventional Kalman filter covariance propagation and update equations are explicitly accounted for. Errors induced by selective availability periods are minimized by these two modifications.

Abstract: A counting section includes: a first gyro pulse counter which counts gyro pulses from each of X-, Y-, Z- and S-axis gyroscopes during each counting period after being reset immediately before the start of the counting period and outputs the count value as a first gyro pulse count value at fixed time intervals; and a second gyro pulse counter which is reset at said fixed time intervals, counts the gyro pulses and outputs the count value as a second gyro pulse count value.

Abstract: A low cost tracking system employing satellites of the global positioning system (GPS) is suitable for applications involving radiosondes, sonobuoys, and other objects. The tracking system includes a sensor mounted on each object which digitally samples the GPS satellite signals and records them in a data buffer. The digital samples are then transmitted, at a rate lower than that at which the GPS satellite signals were sampled, over a data telemetry link, interleaved with other telemetry data from the object. The GPS data is processed in a data processing workstation where the position and velocity of the sensor, at the time the data was sampled, is computed. The data buffer in the sensor is periodically refreshed, and the workstation periodically computes the new position and velocity of the sensor. Differential corrections are also provided at the workstation to aid in signal acquisition and to increase the precision of the position fix.

Abstract: An apparatus senses a free stream flow parameter using airflow adjacent an air vehicle. The apparatus includes a first sensor sensing a longitudinal axial component and a lateral axial component of a parameter of local airflow immediately adjacent the first sensor. A second sensor senses a longitudinal axial component and a second axial component perpendicular to the lateral axial component sensed by the first sensor of a parameter of local airflow immediately adjacent the second sensor. The first and second sensors are mounted on the air vehicle such that a longitudinal axis of the first sensor lies in a first plane including a longitudinal axis and a longitudinal axis of the second sensor means lies in a second plane substantially perpendicular to the first plane and including the longitudinal axis of the first plane. A correction unit obtains a signal representing the free stream flow parameter as a function of the parameter components sensed by the first and second sensors.