Abstract: A guidance module for an underground horizontal boring assembly. The module determines the pitch angle of the boring tool independent of roll using a single accelerometer sensor. The accelerometer sensor has a single sensitive axis which is aligned parallel to, and preferably coaxial with, the longitudinal axis of the boring tool. The accelerometer sensor is calibrated to obtain a temperature offset and a gain compensating gain factor. Data samples are read from the accelerometer sensor while the boring tool is rotating. The temperature is read from the temperature sensor. The data samples from the accelerometer sensor and the temperature from the temperature sensor are transmitted to a processor. The processor applies simple average filtering to the accelerometer data samples to get an average result, and adjusts the average result for gain. The average result is adjusted for the temperature offset and for the gain compensating gain factor.

Abstract: A system for regulating an alternating current voltage source has a pair of P-channel MOSFETs and a pair of N-channel MOSFETs in a bridge configuration with an inductor-capacitor tank there between. A processor in conjunction with a feedback circuit regulates the energy transferred to the tank by modulating the pulse width of signals that are output from the processor and which are used as inputs to the gates of the MOSFETs. By increasing or decreasing the pulse widths transmitted to the various gates of the MOSFETs, the processor increases or decreases the energy transferred to the tank. The feedback circuit is connected between the tank and the processor so that the processor can compare the feedback voltage from the tank to a threshold level in the processor and modify the pulse widths at the output of the processor accordingly.

Abstract: A method and apparatus for linearizing an analog signal. The signal is converted into a digital form and digital gain and offset words are fetched based upon the value of the measurement signal and any other parameters which affect linearity, such as temperature for example. The digital gain and offset words are converted to analog values and inserted into an analog signal path of the measurement signal.