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.