Abstract: A compass which is self-compensating for dip of its pointer arms irrespective of variances in the earth's magnetic forces at different geographical locations includes a magnet disposed beneath respective proximal portions of the pointer arms so that the pointer arms are parallel to the magnetic field of the magnet, with the magnet constructed to be counterbalancing with regard to the earth's magnetic fields. In a preferred embodiment, the magnet comprises a plastic disk with magnetic particles embedded therein, the disk having a chordal portion removed therefrom immediately beneath one pointer arm, and a damper pan assembly is controlled by a lift arm to selectively dampen the movement of the pointer arms.

Abstract: An error sensing system for use in marine autopilot systems of the type having a photographic film compass disk aligned with the direction North and sensing means associated with the disk is operative to sense relative movement between the disk and the sensors in response to changes in the heading of the vessel. A first direction error surface portion on the disk has opaque and transparent areas defining a zero reference therebetween, a second magnitude error surface portion on the disk has a second zero reference position in predetermined relation to the first zero reference position and an area of variable transparency extending along the second surface portion. The first and second surface portions are defined by images along the peripheral surface of the photographic film disk.

Abstract: Apparatus for steering a vessel and maintaining it on a preset course through the combination and arrangement of an incremental encoder and a heading reference circuit is disclosed. The encoder includes circuitry operative to generate a directional signal and count pulse for each incremental movement of the vessel away from the preset heading and for transmitting same into a heading reference circuit. Counting means are included in the heading reference circuit including adjustable reference setting means to set the counter at a reference position corresponding to the preset heading. The counter is responsive to the pulses received from the incremental encoder to count in a positive or negative direction under the control of the directional signals. A sign-detector in the counter detects whether the total number of pulses is positive or negative with respect to the reference position and generates a signal representative of the direction of the net change.

Abstract: A pair of referencing coils are mounted in direct association with a rotatable scale having a reference position index and a code strip. A reference position sensor generates a signal in response to alignment of the reference position sensor with the reference position index, and magnetic members are operative to normally align the scale with magnetic north. An electrical drive is provided for alternately energizing the reference coils disposed at predetermined angles to one another and to the magnetic members which respond to the energization of each coil and advance the reference position index toward the reference position sensor. Preferably alignment coils are positioned at equal angles to either side of the reference position sensor so that drive requirements are such that the current applied to each coil is only necessary to draw the magnets and associated scale through an angle which is just greater than one-half the total included angle between the coils.

Abstract: A recreational or sportman's compass is comprised of an inner vial including a compass needle which together with an azimuth ring is resiliently mounted within a housing so as to be rotatable together or independently of one another. The vial is assembled together with the outer azimuth ring and retainer in such a way as to permit assembly of the parts into snug-fitting concentric relation to the housing without the necessity of positively fastening or affixing the vial to the housing.

Abstract: A self-contained compass apparatus includes a sensing circuit and power source which are enclosed along with a compass unit within a chamber which is adaptable for suspension at extended distances into a borehole, such as, an oil well, so as to assist in determining direction and orientation of articles, such as tooling, positioned in the well.

Abstract: Data acquired from a source such as a coded disc is processed so as to be free of ambiguities associated with boundary transitions where the data source produces groups of bits which have least significant ordering and higher significant ordering. Wherever a common transition boundary between the bit groups occurs, ambiguities from misalignment of these boundaries are avoided by controlling the higher ordered bit transitions from the lower ordered bit transitions. Circuitry tracks and stores the higher order bits by synchronous updating whenever no misalignment or skew sensitive transitions are encountered. Logic circuitry continuously inspects the lower significant bits to determine the presence or absence of a zone surrounding the common transition boundary and also detects the actual passage and direction of the transition boundary in the lower significant bit group. This logic corrects the counter stored higher order bit counts in conformity with the status of the lower significant bit states.

Abstract: A magnetic compass has been devised which is of the type having a pivot point displaced above the plane of the permanent magnets so that the distance of displacement of the pivot point with respect to the center of force will reduce the tilt angle or tipping otherwise caused by changes in latitude when the compass is to be operated in different parts of the world and a spherical needle bearing can be employed at the pivot point as a result of the increased pendular effect achieved by displacing the pivot point above the magnets. The need for a lift assembly to cushion the pivot point is eliminated while providing for an extremely rugged and versatile magnetic compass which will serve as a light, portable pocket transit capable of measuring horizontal and vertical angles as well as being used as a prismatic compass, level, clinometer, plumb or alidade.

Abstract: Concentrated light beams from two or more sources are passed through a spirit level mounted in a portable housing and the presence of the light beam columns after passing through the level is detected to indicate on-level or the direction of off-level for a remote plane or surface. In one form, detection circuitry selectably lights one or a pair of indicator lamps appropriately arrayed on a display panel for establishing that the remote spirit level is in a level orientation or the direction of out-of-level. The detector circuitry can include cross-coupling to prevent an erroneous indication of the direction of out-of-level. In another form, multiple pairs of concentrated light sources and detectors are arrayed along the length of the spirit level and digital circuitry converts the detected outputs into a direct digital display and/or into a format appropriately useful for other digital data handling equipment.

Abstract: Data acquired from a source such as a coded disc is processed so as to be free of ambiguities associated with boundary transitions where the data source produces groups of bits which have least significant ordering and higher significant ordering. Wherever a common transition boundary between the bit groups occurs, ambiguities from misalignment of these boundaries are avoided by controlling the higher ordered bit transitions from the lower ordered bit transitions. Circuitry tracks and stores the higher order bits by synchronous updating whenever no misalignment or skew sensitive transitions are encountered. Logic circuitry continuously inspects the lower significant bits to determine the presence or absence of a zone surrounding the common transition boundary and also detects the actual passage and direction of the transition boundary in the lower significant bit group. This logic corrects the counter stored higher order bit counts in conformity with the status of the lower significant bit states.

Abstract: A hand-held digital compass employs an incremental encoder including a digit code disc and sensor unit which are so interrelated with a logic circuit as to permit automatic referencing of the compass when power is initially applied; and further permits use of an extremely small digit code disc which in cooperation with the sensor unit will permit digital recording of the direction and degree or extent of displacement of the compass in a given direction. The logic circuit employed is self-correcting for errors caused by input line noise and permits utilization of a simplified counting circuit for reading and digitally displaying degrees of movement between zero and 360.degree..

Abstract: Cell boundary ambiguities associated with data read from tracks of sequential cells from a data source such as a coded disc are avoided by incorporating specially coded cells in each track and sensing the status of these cells to determine the proper timing for enabling accurate readout from the track. The special cells are arranged such that data read therefrom is common at the bit cell boundaries but differs for at least a segment around the center of each bit cell. The specially coded tracks can be arranged to produce significant data as well as to control enabling of the data readout.

Abstract: Angular displacements are measured relative to either an external magnetic field as in a compass or relative to a vertical reference as in inclinometers or the like by selective orientation of the device. A bistable weight balancing apparatus and a dual bearing support arrangement cooperate to provide two discrete balancing positions. Horizontal positioning of the device results in relatively even weight distribution around a needle bearing support which permits alignment with the polar line of an external magnetic field. Vertical orientation of the device permits an offset redistribution of the weight in the bistable balance to define a vertical reference. Digitally coded apparatus such as a disc permits circuitry to detect instantaneous orientation of the frame relative to a magnetic field or vertical reference. Circuitry logically cooperates with data read from specially coded tracks to insure accurate strobing of the output data free of ambiguities.

Abstract: A system enables selective control of instantaneous motor armature position and, thus, the corresponding position of one or more elements driven by the motor. As utilized in a high speed printer, the system governs positioning of a printhead, enabling high speed movement of the latter from one location to the next and yet bringing it to a complete stop exactly at a selected or desired location. Additionally, the system enables position control with respect to movement over different predetermined distances such as, in the printing embodiment, of character or word spacings, carriage returns, tab sets and vertical indexing. Operationally, armature position-representative pulses are counted and analyzed to determine during acceleration when one desired position has been reached and, during subsequent deceleration, to determine when zero movement has been reached.