Abstract: An illuminating device includes a mounting plate adapted to be mounted on a bottom of a magnetic compass in a first direction. The mounting plate has a central axial hole passing therethrough in a second direction transverse to the first direction and defining a central axis, and a battery receiving chamber for receiving a battery. A lighting member is disposed on the mounting plate, and has a first lead electrically connected to a first pole of the battery. First and second conductive members are connected respectively to a second lead of the lighting member and a second pole of the battery, extend above the central axial hole, and are spaced apart from each other along the central axis. A cover plate is disposed on the mounting plate for closing the chamber, and is rotatable relative to the mounting plate about the central axis between locked and unlocked positions.

Abstract: An compass having an electronic magnetic field sensor and an analog directional display is disclosed wherein a signal from the field sensor proportional to one component of the earth's magnetic field is alternated in polarity and integrated to produce a triangular waveform the frequency of which is proportional to the strength of that field component and wherein a triangular waveform having a frequency proportional to the second component of the earth's magnetic field is produced in the same manner. These values are used by a microcontroller to control an air-core gauge such that a disk with reference markings attached to the gauge remains positioned with one of the reference markings facing either magnetic or true north. A resistor ladder network is also connected in parallel to the inputs of the integrators and controlled by the microprocessor through a shift register in order keep the integrators out of saturation.

Abstract: A rearview mirror assembly is disclosed for use in a vehicle that includes a mirror housing, a mounting structure for pivotally mounting the mirror housing to the vehicle such that the mirror housing may be both vertically and horizontally tilted, a compass sensor disposed in the mirror housing and coupled to a compass processing circuit, and a tilt detector for detecting when the mirror housing has been tilted from a prior position and for generating and transmitting a tilt detection signal to the compass processing circuit. The compass processing circuit may then respond to the reception of the tilt detecting signal by compensating the compass reading and/or display or by recalibrating the compass.

Abstract: The invention concerns a tilt-compensating indicator device for a compass (100) comprising a magnetic field detection device (20) which is mounted on a conical bearing (7) and is accommodated in a housing (100') of the compass (100). The indicator device (30) is rotatably mounted on the magnetic field detection device (20) by means of a receiving bearing (8,10) whose bearing shaft (8), accommodated in bearing elements (10) of the magnetic field detection device (20), extends substantially at right-angles to the north-south direction of the magnetic field detection device (20).

Abstract: The present invention provides a compass comprising an at-least-partially-transparent housing having a top and a bottom, a vertically orientated, conical pivot bearing, and a magnetic detection means which is mounted on the vertically-oriented conical pivot bearing. The magnetic detection means thereby is capable of rotating in a substantially-horizontal plane. The magnetic field detection means is provided with a radially-extending, tilt-compensating, indicator device. The indicator device has at least one spacer element which is spaced from the magnetic field detection means, the spacer element projecting from the indicator device and being directed towards one of a top of the housing of the compass and a bottom of the housing of the compass.

Abstract: An electronic compass has a compass housing. An electronic magnetic field sensor is disposed in a fixed position relative to the compass housing. A magnet is rotatably mounted relative to the magnetic field sensor and independently aligned with a terrestrial magnetic field. The magnet has a magnetic field with a magnetic field direction and the electronic magnetic field sensor is located within a range of influence of the magnetic field. The electronic magnetic field sensor has a first magnetoresistor with a first fixed reference axis and an electric resistance of the first magnetoresistor is a function of a first angle of rotation between the fixed first reference axis and the direction of the magnetic field. The electronic magnetic field sensor defines a first differential bridge circuit and the first magnetoresistor is disposed in the first differential bridge circuit which during operation of the compass, supplies an output voltage dependent on the first angle of rotation.

Abstract: A three-dimensional homologous surveying instrument includes a base with an outer spherical shell mounted thereon for receiving therein a ring-shaped shell holder, an intermediate spherical shell and an inner spherical shell with respective zero references at in a homologous relationship with each other. The inner spherical shell rotates within the intermediate spherical shell about X-axis. The intermediate spherical shell rotates within the ring-shaped shell holder about Y-axis. The outer spherical shell is positioned in the base to serve as the X-axis. The inner spherical shell and the intermediate spherical shell each have a pendulum at the bottom. The outer spherical shell, the ring-shaped shell holder, the inner spherical shell and the intermediate spherical shell form a gyroscopic device for three dimensional surveying through X-axis, Y-axis and Z-axis concomitantly. The pendulum of the inner spherical shell is mounted with a compass for indicating the direction of the angle of slope being surveyed.

Abstract: A vehicular traveling direction measuring system derives a weighting constant based on a monitored magnitude of the geomagnetic disturbance around a vehicle. Variance values of geomagnetism indicative data and a deviation magnitude from a standard azimuth circle may be used to estimate the geomagnetic disturbance magnitude. Mean data is derived from current cycle data and prior cycle data of the monitored geomagnetism using the weighting constant. The weighting constant determines a rate of dependency upon the current cycle data and the prior cycle data when deriving the mean data. The vehicular traveling direction is derived based on the derived mean data.

Abstract: A method of installing a compass system includes the steps of mounting the electronic compass in a vehicle, coupling the electronic compass to a power source of the vehicle, downloading precalibration data into the electronic compass after the electronic compass has been mounted in the vehicle, and initiating a precalibration routine in the vehicle that is headed in a predetermined direction. The method may further include the steps of identifying characteristics of the vehicle and selecting precalibration data corresponding to the identified vehicle characteristics. The precalibration data selected corresponds to a make and model of the vehicle in which the compass may be installed and further may correspond to sets of vehicle options that may affect vehicular magnetism. If the electronic compass is provided as part of a trip computer, the precalibration data is preferably downloaded at the same time that the fuel tank size is downloaded into the trip computer.

Abstract: A rearview mirror assembly is provided for a vehicle which incorporates a self-contained magnetic field sensor in the mirror housing. When mounted to a fixed pivot point in a single ball mounting bracket, the mirror housing pivots around the magnetic field sensor. When the magnetic field sensor is mounted within the mirror housing either to the housing or to the mirror, compensation for the rotation position of the mirror about a vertical axis is provided by an empirically predetermined compensation value whereby direct reading of the angle is adjusted by a processor or by mechanically mounting the field sensor at an angle representative of the compensation value. Other ways of rotation compensation are also disclosed. Compensation for tilt about a horizontal axis is provided by an elliptical compensation algorithm in a microprocessor.

Abstract: A geomagnetic direction sensor has a plurality of magnetic cores for converging terrestrial magnetism arranged circumferentially with pre-set gaps, and magneto-resistive effect devices in the gaps so as to lie substantially at right angles to the direction of the magnetic field in the gaps. The geomagnetic direction sensor has at least a pair of magneto-resistive effect devices lying substantially at right angles to each other. The magnetic core is formed of a magnetic material having soft magnetic properties. The current is supplied to the excitation coils placed around the magnetic core for applying a bias magnetic field to the magneto-resistive effect devices. Another set of magneto-resistive effect devices are connected in series with the magneto-resistive effect devices arranged within the gap so as to be substantially parallel to the direction of the magnetic field.

Abstract: In a sourceless orientation sensor, the sensor measures the three orientation angles azimuth, elevation and roll in a fixed reference three-dimensional coordinate frame. The sensor utilizes a three-axis magnetic sensor to measure changes in the Earth's magnetic field in order to determine the azimuth and roll (or elevation) angles after the elevation (or roll) angle has been determined by other means. A first embodiment utilizes a separate sensor to measure the elevation (or roll) angle in a fixed reference three-dimensional coordinate frame while a three axis magnetic sensor is used to measure the Earth's magnetic field. The azimuth and the roll (or elevation) angles are then determined from these measurements. A second embodiment utilizes a combination of a three-axis accelerometer to sense the Earth's gravity to measure the absolute elevation and roll angles for slow motions and a two-axis rate sensor to measure the azimuth and elevation velocities in the sensor frame.

Abstract: An electronic compass includes at least two coil assemblies. Each coil assembly has a magnetic axis which is oriented at a known angle to that of the other coil. Each coil assembly has a pair of substantially identical coils having magnetic axes that are parallel in a reverse sense. The compass further includes an oscillator which oscillates at a frequency which is dependent upon the inductances of the coils. A current source causes current to flow in the coils and a switch alternately couples the current source to each of the coils of the coil assemblies. A processor analyzes the frequencies of oscillation of the oscillator when each of the coil assemblies is coupled to the current source in order to compute geographic orientation based upon the analysis.

Abstract: A magnetic composition comprising nanocomposite particles comprising from about 0.001 to about 60 weight percent of magnetic nanocrystalline particles dispersed in from about 40 to about 99.999 weight percent of a discrete phase matrix, and a continuous phase matrix, wherein the discrete phase resides in interstices within the continuous phase matrix.

Abstract: A slope measuring device, suitable for use on bicycles or other vehicles. Slope measurements are made by sensing the position of a weighted disk rotating in a cylindrical chamber. The disk is hermetically sealed and it's position is electrically monitored. Damping methods prevent the disk from moving radically over rough terrain and an onboard microprocessor processes disk readings to make accurate slope calculations. The device clamps to the handle bars of a bicycle and may be battery or generator powered.

Abstract: An alternating bias current is made to flow through a coil wound around an MI device incorporated in an oscillation circuit, and an alternating-current bias magnetic field is applied to the MI device. An amplitude-modulated waveform corresponding to peaks which alternate between two different heights is provided at the output of the oscillation circuit in accordance with an impedance variation in the MI device according to an external magnetic field and the alternating-current bias magnetic field. The difference in height between the peaks corresponds to the strength of the external magnetic field. The output of the oscillation circuit is envelope-detected by an envelope detecting circuit, and an alternating-current component from which a direct-current component is eliminated is inputted to a comparator. The comparator provides an output signal having a digital waveform pulse-width modulated according to the difference in height between the peaks.

Abstract: A vehicle compass system having a magnetic field sensor coupled to a processing circuit which samples the sensor data and implements a calibration routine that generates compensation signals to compensate the sensor for the effects of vehicular magnetism so that accurate heading information can be displayed on a display coupled to the processing circuit. If the signal levels detected are outside of a variable threshold, then the calibration routine is run. Also provided is a circuit for receiving vehicle position information in response to which the processing circuit adjusts the signals supplied to the display in order to account for magnetic variations between the true north and magnetic north.

Abstract: An apparatus is disclosed which is utilized to provide positional information relative to an external magnetic field. The apparatus includes a rotatably mounted slotted disk wherein the slot is continuously varying in width around the circumference of the disk. The continuously variable width of the slot serves as a light attenuating mask. The disk incorporates an elongated magnet means which causes it to rotate in relation to an external magnetic field. The slotted disk may be placed in a fluid filled chamber. A first and second aperture are located on the top and bottom of the chamber, the apertures defining an emission passage through the chamber. The apertures have a rectangular length approximately the maximum width of the slot. The slotted disk is intermediate the apertures. A source detector, source emitter and an area source means is provided. The area source means is caused to emit a continuous uniform light signal which is attenuated by the slotted disk.

Abstract: A gimballed compass apparatus with digital logic is disclosed which provides directional and attitudinal data. The apparatus comprises a rotatably mounted slotted disk wherein the slot is continuously varying in width around the circumference of the disk. The disk incorporates an elongated magnet which cause it to rotate in relation to an external magnetic field. A first and second aperture are located on the top and bottom elements of the chamber defining a light passage. The apertures have a rectangular length approximately the maximum width of the slot. The slotted disk is positioned intermediate the apertures. A light housing is provided below the chamber and includes a light source. A linear array of source detector are provided above the chamber. Each source detector element provides a response proportional to the specific amount of light incident upon it. The light beam is reflected from the aperture by a mirror to a beam focusing device.

Abstract: An electronic audio/visual direction indicator for underwater or other types of navigation which gives unobtrusive and continuous directional feedback without the need for manual manipulation.

Abstract: The present invention provides a method and apparatus for utilizing spin valve magnetoresistance devices for the measurement of weak magnetic fields. The magnetoresistive element consists of a pinned ferromagnetic layer and a soft ferromagnetic layer separated by a thin spacer layer. The pinned layer may be pinned by high intrinsic coercivity, or by a neighboring antiferromagnet or high coercivity ferromagnet layer. An oscillating magnetic field is applied to the device. The amplitude of the excitation field is large enough to reverse the magnetization of the soft layer during each cycle, but small enough that the magnetization direction of the pinned layer is not much affected. In one embodiment, the applied field is applied using a current strip deposited onto the top of the other layers, so that the entire device can be produced on a single chip.

Abstract: A navigational device that employs the azimuthal position of a housing assembly relative to the Earth's magnetic field to alter light such that the altered light becomes a direction indicator. By using the altered light as a signal the device is both economical and reliable.

Abstract: Advertising information is preloaded into a collection of remote receiving and presentation devices. A presentation command delivered to the device then causes presentation of the stored advertisement. Each stored advertisement is also associated with one or more presentation conditions causing, when detected, automatic presentation. Such presentation conditions include proximity to a given location, scheduled periodic presentation, time of day presentation, and a variety of other conditions detectable at the remote presentation device. The illustrated method and apparatus for advertising presentation requires but a single broadcast signal transmission of a given advertisement, but provides multiple presentations of such advertisement at the presenting devices. In this manner, the advertiser enjoys efficient use of broadcast signal transmission time.

Abstract: A compass circuit has a magnetic field sensor adapted to be positioned in a vehicle near a source of varying magnetic fields. A detector is coupled to the compass circuit for providing a signal applied to the compass circuit which responds for displaying the compass heading prior to the magnetic field disturbance to provide accurate heading information. In a preferred embodiment, the detector senses when a door is opened and the compass heading prior to the opening of the door is displayed.

Abstract: A compass for mobile parabolic antenna includes a compass sphere having a transparent shell with an elevation dial and a magnetic core encapsulated by the transparent shell with fluid filled therebetween with a bubble enclosed within the transparent shell and a directional mark pointing to a fixed direction on the magnetic core, an annular plate having a location dial and a satellite name dial provided on edges of the plate, a cover plate having a central hole and a plurality of arcuated grooves, and a base plate having a circular depression, a plurality of arcuated recesses corresponding to the grooves on the cover plate defined in the depression, and a central bore corresponding to the central hole on the cover plate so that the compass sphere can be secured within the central hole and the central bore and the annular plate can be rotatably received by the circular depression when the cover plate couples with the base plate.

Abstract: A geomagnetic direction sensor has a substrate, at least two magneto-resistive effect devices and a coil for generating the bias magnetic field. The substrate retains shape symmetry when rotated through 90.degree. and includes plural magnetic cores for converging the geomagnetism. The magnetic cores are arrayed circumferentially of the substrate and interconnected with one another by a non-magnetic material. At least two magneto-resistive effect devices are provided in register with the magnetic gaps so as to be substantially at right angles to one another and to the direction of the magnetic field of the geomagnetism in the magnetic gap region. The substrate also includes a coil for generating a bias magnetic field for impressing a bias magnetic field to each of the magneto-resistive effect devices.

Abstract: The present invention relates to a sensor system that uses two sensors for measuring and monitoring of angular position of a member in two or three axes. The sensor system of the present invention preferrably uses a pair of magnetoresistive sesors that are maintained in the same plane and in orthogonal configuration with respect to each other, and which reference their position according to the Earth's magnetic field or a magnetic field provided by a user. Accordingly, the sensors of the present invention are useful for a variety of purposes, including, virtually any application that requires monitoring and measurement of any combination of roll, pitch, and yaw.

Abstract: A compass circuit has a magnetic field sensor adapted to be positioned in a vehicle near a source of varying magnetic fields. A source of correction signals is coupled to the compass circuit for providing correction signals applied to the compass circuit for correcting the heading display of the compass circuit when differing levels of magnetic field disturbance occurs to provide accurate heading information. In a preferred embodiment the source of correction signals includes a detector circuit coupled to the vehicle accessory for providing signals directly corresponding to the source of magnetic field interference.

Abstract: An improved electronic magnetometer has a flux-concentrating core making grazing contact with a magnetically conductive element which is preferably part of a piezoelectric transducer. The core and transducer are mounted so as to make non-coherent, chattering contact when the transducer is caused to vibrate. A pickup coil attached to a signalling device enables a user to find a null in a field of magnetic flux with novel accuracy.

Abstract: A gimballed compass apparatus is disclosed which provides directional and inclinational data. The apparatus comprises a rotatably mounted slotted disk wherein the slot is continuously varying in width around the circumference of the disk. The disk incorporates an elongated magnet which causes it to rotate in relation to an external magnetic field. A first and second aperture are located on the top and bottom elements of the chamber defining a emission passage. The apertures have a rectangular length approximately the maximum width of the slot. The slotted disk is positioned intermediate the apertures. An emission housing is provided below the chamber and includes an emission source and a first source detector. A second source detector is provided above the chamber. The source detectors provide a response to the intensity of emission incident upon them.

Abstract: An attitude sensor comprises a spherical ball suspended in a fluid contained in a housing. The ball is maintained neutrally buoyant with respect to the fluid and out of direct contact with the housing. A means is provided for detecting the orientation of the ball. The sensor is particularly useful as a compass, in which case one or more magnets may be provided within the ball or a passive magnetic element is provided which is influenced by the earth's magnetic field.

Abstract: A low cost, simple apparatus is disclosed which can be used to provide positional information relative to an external magnetic field. The apparatus comprises a rotatably mounted slotted disk wherein the slot is continuously varying in width around the circumference of the disk. The disk incorporates an elongated magnet which causes it to rotate in relation to an external magnetic field. The slotted disk is placed in a fluid filled chamber. A first and second aperture are located on the top and bottom elements of the chamber defining an emission passage. The apertures have a rectangular length approximately the maximum width of the slot. The slotted disk is intermediate the apertures. A source detector is provided below the chamber proximal an emission source, and a second source detector is provided above the chamber. The source detectors provide a response to the intensity of emission incident upon them.

Abstract: An apparatus for determining the direction of a magnetic field is provided with a plurality of magnetically sensitive components arranged with their sensing axes equally spaced around a circular configuration. Each magnetically sensitive component is capable of providing a binary signal representing the resolution of the direction of a magnetic field along one of the two possible directions aligned with its sensing axis. The binary signals from each of the plurality of magnetically sensitive components is arranged to provide a grey code output that can be used to directly determine the direction that the apparatus is pointing toward. The compass points that can be resolved is related to the number of magnetically sensitive components by a ratio of two to one. For example, the use of four magnetically sensitive components permits the resolution of eight compass directions.

Abstract: An electronic audio/visual direction indicator for underwater or other types of navigation which gives unobtrusive and continuous directional feedback without the need for manual manipulation.

Abstract: An electronic compass has a display including a reference pointer that indicates a reference heading stored in response to an input signal. The reference heading is the current heading at the time of the input signal, and the reference pointer in the display is updated as the orientation of the compass changes.

Abstract: A directional indicator made to fasten around the wrist for guiding the user in a predetermined direction, including a magnetized needle attached rotating dial balanced on a pointed pin inside a casing, a needle pointer fastened to a center shaft on the rotating dial, a convex lens covered on the casing over the rotating dial and marked with a fluorescent mark, whereby the needle pointer is maintained in alignment with the fluorescent mark to guide the user toward the predetermined direction.

Abstract: A switched-magnetization closed-loop magnetometer having a magnetoresistive bridge for sensing external magnetic fields. The output signal from the bridge to an amplifier, is magnetically nulled by a feedback coil. Each of the bridge elements have a magnetic easy axis that is periodically and magnetically flipped by a reset coil. The output of the amplifier goes to an analog switch and an integrator in one or the other order. The output of the analog switch or the integrator may go on to a sample and hold circuit, or other sampling device, that alternately samples the output to it in synchronism with the reset coil. The output is processed by a low pass amplifier. A clock provides signals to the reset coil, the analog switch and the sample and hold switch.

Abstract: When the body of an automobile equipped with a stand-alone navigation system is magnetized by an external magnetism, an unknown magnetization vector is determined by correcting the known magnetization vector. Even very small changes in the magnetization vector can be corrected without putting a burden on the user of the automobile. A magnetization vector directed from a reference position toward the center of a magnetic circle which indicates the magnetized condition of the automobile body is detected, and a geomagnetic vector which is directed from the reference position in the direction in which the mobile body progresses is detected. An instantaneous direction vector which is directed from the center of the magnetic circle in the direction in which the mobile body progresses and which has a direction angle is calculated.

Abstract: A magnetic sensor mounting assembly embodying the present invention includes a base plate having cradles for pivotally receiving and adjustably locking a sensor supporting platform thereto. The base plate can be attached to an existing rearview mirror mounting member. The assembly further includes a cover providing access for adjusting the platform to a horizontal position and for allowing the rearview mirror mounting stem to extend therethrough.

Abstract: An instrument console for use in scuba diving includes a console body having a first end adapted for connection to a pressurized air line, and a second end opposite the first end, at least one instrument being secured within the console body, a compass having top and side Lubber Lines, a compass housing configured to accommodate the compass and being connected to the second end of the console body to pivot relative to the console body, so that while held in front of the swimming diver, the compass may be maintained and read in a generally horizontal position, and the instruments may be viewed in a generally vertical position.

Abstract: A compact hand-held viewing apparatus that automatically determines the three-dimensional direction in which it is pointing and automatically presents information to the user related to features which are visible in the field of view of the apparatus in that three-dimensional direction. Any given embodiment of the invention is intended to be used for viewing a predetermined subject matter, such as astronomical features of the night sky or geographical features of the distant terrain. Included within the apparatus is a database with data about the predetermined subject matter correlated with three-dimensional direction. The apparatus is configured to provide data from the database in real time to the user as the user observes the field of view in a selected three-dimensional direction.

Abstract: A position sensor has a ring of a material of high permeability that is floated on a liquid within a hermetically sealed toroid, so as to hold the ring in a horizontal position. Exciting coils are distributed uniformly about the ring to enclose the cross section thereof, and receiving coils are distributed uniformly about the circumference of the ring.

Abstract: A magnetic field guidance system for guiding a movable carrier such as a drill assembly with respect to a fixed target includes a pair of magnetic field sources at one location, such as the carrier, and a highly sensitive magnetic field detector at the other location, or target. The first field source is driven by an alternating current to produce a low frequency alternating axial field, while the second source is a magnet which produces a field perpendicular to the axis of the first field. Where the magnetic field sources are mounted on a rotatable drill assembly, the second source may be a permanent magnet which rotates with the drill assembly. The detector may be a fluxgate magnetometer which senses the direction of the target location with respect to the direction of the axial field by determining the deviation from perpendicular of the two magnetic fields at the target location.

Abstract: A flux-gate sensor orientation method which minimizes display jitter in electronic compasses which employ an n-point display or which calculate headings using the arctangent method. The method entails orienting the flux-gate sensor in a direction of plus or minus .+-.360.degree./2n relative to actual magnetic direction, so that instability points occur at display point boundaries. The method of the present invention finds application in microprocessor-based electronic compass systems but also makes possible the construction of a simple electronic compass employing small scale integration logic instead of a microprocessor.

Abstract: A tilt-compensating magnetic compass formed by a capsule enclosing a rotatable pointer to indicate direction and a rotatable magnetic-field detector provided with a permanent magnet. The detector, which is rotatable about an axis colinear with the axis about which the pointer rotates, orients itself with respect to the earth's magnetic field, the detector being tiltable to a degree depending on the inclination of the magnetic field and on the attitude of the compass with respect to the horizontal plane. The detector is mechanically linked to the pointer so that rotation of the detector results in a corresponding rotation of the pointer regardless of the degree of tilt, whereby the pointer accurately indicates direction. The linkage consists of a pin projecting from the detector and passing through a slot in a fork extending from the pointer, whereby when the detector tilts, the pin then shifts within the slot, but remains coupled to the fork to maintain the linkage without imparting movement to the pointer.

Abstract: A miniaturized electronic magnetic compass system, or the like, is mounted in a substantially cylindrical gimbal ring unit of about 0.75 in diameter, and 1.25 in length. Critical to the small size is the pendulum that positions the internal magnetic detector by gravity relative to the earth's surface. Thus, a pendulum formed of tungsten has its curved bottom surface formed of a central spherical surface and two flanking cylindrical surfaces meeting in two planes disposed at an angle intersecting with the pendulum axis of rotation. The mass of the detector is centered by resilient conductive spring plates bearing on gimbal pivot shafts, which also serve as electrical connectors for the detector. Thus, two separated shaft ends journalled in one gimbal ring, which is insulated to electrically isolate the shaft ends serve as two conductors. The gimbal system is damped in a perfluorocarbon oil.

Abstract: A hand-held instrument adapted selectively to provide a sportsman, such as a mountain climber, with readily-readable indications of the existing altitude or direction. The instrument includes a magnetometer which yields an analog signal as a function of direction and a pressure sensor which yields an analog signal as a function of atmospheric pressure. These analog signals are converted into corresponding digital signals and applied to a microprocessor which acts to control an LCD display having two display modes--one providing a numerical readout of altitude, the other a 360 degree readout of direction. When the microprocessor is switched to the altitude mode, it then processes the signal derived from the pressure sensor to yield a digital output for operating the display to indicate the existing altitude. When the microprocessor is switched to the direction mode, it then processes the signal derived from the magnetometer to yield a digital output for operating the display to indicate the existing direction.

Abstract: The invention is a motion sensitive, battery operated compass utilizing Hall effect digital switches to sense the orientation of the compass in relation to the earth's magnetic field. A vibration sensing circuit serves to turn the compass on when it is in motion, and to turn the compass off when it is at rest. A chopper circuit is provided to interrupt the power supply at a predetermined frequency to conserve battery power. The Hall effect switches are mounted in a known relationship to a rotating magnet allowing selection and decoding of the sensor outputs to provide signals for the operation of an alpha numberic display.

Abstract: A stud finder includes a magnetic subassembly for detecting the presence of a ferrous metal object, such as the head of a nail or screw, in a wall, with the magnetic subassembly being mounted at one end of a base member. A level vial is mounted at the other end of the base member, and a slot is formed in the base member between the magnetic subassembly and the level vial. When the base member is placed against a wall and the presence of a stud is detected by the magnetic subassembly, the base member is moved to a position in which the level vial indicates level. The slot has its longitudinal axis oriented perpendicular to the longitudinal axis of the level vial, so that the user can place a vertical mark on the wall through the slot. The slot is oriented so as to be in vertical alignment with the nail or screw head, when the base member is moved such that the magnetic subassembly is directly over the nail or screw head.

Abstract: The improvement of the present invention provides a camper's compass having a plate or member, such as an arcuate bow, having a direction pointer, which is pivotably mounted over the compass housing in such as way that it can swing between a normal forward position in which the compass is oriented in the desired direction of travel, and a diametrically opposed or reverse position. By pivoting the arcuate bow or member from its forward position to its reverse position, the user can set the return direction to the point of departure on the compass. The direction of a reverse path back to his point of departure is readily determined without making any mathematical calculations or trying to use the orienting means of the compass in reverse positions. This simplified manner of setting a return path on the compass eliminates confusion which otherwise may occur and result in disorientation of a user in his attempt to return to his point of origin.