Abstract: A borehole survey method employs a first sensor for measuring angular rate, and a second sensor or sensors for sensing tilt, and a rotary drive for the first and second sensors, and includes the steps:(a) operating the drive and the first and second sensors at a first location in the borehole to determine the azimuthal direction of tilt of the borehole at such location,(b) then traveling the first and second sensors and the drive lengthwise of the borehole away from the location, and operating the drive and at least one of the first and second sensors during such traveling to determine changes in borehole alignment during such traveling.

Abstract: The invention concerns efficient transmission of borehole survey signals or data from depth level in a borehole or well to the well surface, for analysis, display or recordation; further it concerns supply of DC power downwardly to the instrumentation via the same wireline via which such survey data or signals are transmitted upwardly.

Abstract: Survey apparatus and method employs a free gyroscope for fast determination of azimuth, free gyroscope alignment being periodically corrected by a rate gyroscope which is periodically rotated for accurate azimuth determination. An accelerometer is also usable in conjunction with the gyroscopes for tilt determination. More generally, method and means is provided for calibrating (initially or periodically) an angle or position reference device.

Abstract: A method of determining azimuth involves use of an angular accelerometer, and includes:(a) rotating the accelerometer about a first axis while the accelerometer is carried on a body which is itself rotating about a second axis, and(b) detecting the accelerometer output of the accelerometer which is caused by said rotation.The accelerometer may for example be rotated in a bore hole in the earth, with the first axis extending in the direction of the hole.

Abstract: Mapping apparatus comprises:(a) a gyroscope and a carrier frame therefor,(b) the gyroscope characterized as having a spinning rotor and torsion structure defining a gimbal, and wherein the rotor spin frequency has a predetermined relation to a resonant frequency of said structure,(c) the gyroscope further characterized as having two input axes, and an output axis about which the spin rotor rotates,(d) drive means operatively connected with said frame to rotate the frame about one of said axis, and(e) the gyroscope having means to detect rotor pivoting about one of said two input axes in response to said rotation of the frame.A second gyroscope may be employed, with its frame. rotated by the same drive means; and the output axes of the two gyroscopes are typically orthogonally related.

Abstract: Survey apparatus and method employs one or more rate gyroscopes having spin axis components directed along an instrument travel axis and in also in directions normal to the travel axis, so that when the gyroscope or gyroscopes are rotated, the earth's rate of rotation will be detected, at all latitudes and at all instrument attitudes.

Abstract: Survey apparatus and method employs a free gyroscope for fast determination of azimuth, free gyroscope alignment being periodically corrected by a rate gyroscope which is periodically rotated for accurate azimuth determination. An accelerometer is also usable in conjunction with the gyroscopes for tilt determination.

Abstract: A system for detecting and monitoring the position of a catheter tip during insertion and after placement of the catheter in a body cavity. A coupling means such as an inductor coil is secured adjacent the catheter tip, and leads extend from the coil along the catheter for connection to external indicating equipment. Energy is propagated through the body to the coupling means from an external source such as an oscillator-driven coil or coils, and relative proximity and orientation of the external and catheter coils is determined by monitoring amplitude and phase of the signal induced in the catheter coil.