Patent ID: 8392139
Filing Date: 2013-03-05
Classification: E21B

Abstract:
1. A multi-point calibration method for the depth of a horizontal directional drilling guiding instrument, comprising the steps of: (1) maintaining a constant power output of a power transmitter in a specific power supply condition; (2) selecting at least two depth calibrations; (3) receiving a signal transmitted from a transmitter and an intensity of a signal at a depth calibration position by a receiving instrument; (4) performing a signal shaping and an analog/digital conversion to the signal received by a signal receiving instrument; and (5) entering the signal into a central digital signal processor, and performing a depth calibration by any compensation method to obtain a required measuring depth; wherein the compensation method includes a linear compensation method, the linear compensation method is implemented by the equation of: where, r is the measuring depth, and M where, M