Abstract: A system and method for controlling the transmitted signal for use in a well logging tool, using an iterative method (preferably the method of steepest descent) such that the transmitted signal more closely resembles a desired waveform.

Abstract: A method for determining orientation of an instrument with respect to earth's gravity. The method includes measuring components of earth's gravity along mutually orthogonal axes. One of the axes is substantially parallel to an axis of the instrument. Tilt of the instrument along two orthogonal axes is measured. One of the tilt axes is substantially parallel to the instrument axis. The instrument is rotated about its axis, and biases of the sensors used to measure the components of earth's gravity perpendicular to the instrument axis are calculated by averaging measurements made by these sensors during rotation. The ratio of gains of these sensors is determined from the range of amplitudes of the output of these sensors during rotation. A roll angle is determined from the bias corrected measurements of components of the earth's gravity perpendicular to the axis. The tilt measurement with respect to the two orthogonal axes is then calibrated by using the calculated roll angle.

Abstract: A method of extracting a phase and amplitude modulation signal impressed on a carrier is disclosed. The method includes generating the carrier at a frequency which is a multiple of the bandwidth of the modulation signal. The multiple equals 4N+1, where N is an integer. The modulation signal is impressed on the carrier, generating a phase and amplitude modulated carrier, The modulated carrier is digitally sampled at a frequency of four times the bandwidth the modulation signal. The digital sampling is initiated substantially contemporaneous with initiation of generating the carrier. A 90-degree phase shift is applied to the digitally sampled carrier to generate a quadrature component of the digitally sampled carrier.

Abstract: The invention is a method of synchronizing a digital telemetry receiver to a digital telemetry transmitter. The method includes the steps of initializing the sampling period of the receiver, measuring the detection time of each signal event detected by the receiver relative to a time window based on the sampling period, accumulating statistics representing the detection times of each of the events, and calculating a refined sampling period based on a linear regression fit of the actual detection time of each event.

Abstract: An apparatus for communicating signals from a well logging tool to a recording unit is disclosed. The logging tool includes a transmitter comprising a source of digital bits representing measurements made by the tool, an encoder connected to the source of digital bits for transforming groups of the digital bits into multivalued symbols, a first in-phase filter and a first quadrature filter connected to the encoder so that first coordinates of the symbols are filtered in the in-phase filter, second coordinates of the symbols are filtered in the quadrature filter, the filters having responses forming a Hilbert transform pair, a digital subtractor connected to the first filters for calculating a difference between outputs of the filters, and a digital-to-analog converter connected to the output of the subtractor for generating signals to be communicated to the recording unit over a communication channel.

Abstract: The present invention is a well logging cable including first conductor elements, each of the first elements consisting of a steel wire surrounded by copper strands and covered in an electrically insulating material, and at least one second conductor element including at least one optical fiber enclosed in a metal tube, copper strands surrounding the tube and the strands covered by the electrically insulating material. The first elements and the at least one second element are arranged in a central bundle. The second conductor element is positioned within the bundle so as to be helically wound around a central axis of the bundle. The bundle is surrounded by armor wires helically wound externally to the bundle.

Abstract: An analog signal is oversampled as a digital time series. The data samples are divided into an even and an odd sequence. Each sequence is independently low-pass filtered and the resulting two reconstructed sequences will be identical to each other and to the original if no isolated error is present in the original sequence. When the three sequences are not equal, an error exists. By noting the location or sample number of the error, the exact location of the error can be determined and the correctly reconstructed sample value can be used to replace the erroneous sample in the original sequence.

Abstract: Sweeps of seismic signals consisting of pulse trains having a predetermined number of pulses in which the periods or durations of the pulses are randomized and in which the wave shape and relative time displacements of the pulses in different trains provides substantially constant spectral level over a frequency range containing several octaves.