Sakata Denki Co., Ltd.

Radic Co., Ltd.

Other

Maeda Corporation Limited

Nobuyoshi Yamazaki

Fumio Sakata

Koji Watanabe

Masaichiro Hatano

Shinichi Endo

Hitoshi Arai

Ken Arai

Masanobu Furukawa

First to third exciting coils are arranged at a reference position. First to third detecting coils are arranged at a measuring subject position distant from the reference position. Voltages induced in the first to third detecting coils are measured when the first exciting coil is excited. Voltages induced in the first to third detecting coils are measured when the second exciting coil is excited. Voltages induced in the first to third detecting coils are measured when the third exciting coil is excited. An azimuth of the measuring subject position from the reference position based on a predetermined calculation by using all nine induced-voltages which are obtained by the first to third detecting coils.

Azimuth measuring method, azimuth measuring apparatus, position measuring method, and position measuring apparatus

In an underground information collecting apparatus which comprises a steel rod with an end to be inserted into the ground and which is for collecting on the ground underground information detected by a sensor mounted in the end, a noise receiving coil is provided to the rod in the vicinity of a main receiving coil which receives a magnetic signal transmitted from a transmitting coil through the rod and which produces a receiving signal. An amplitude and phase adjusting circuit adjusts a noise amplitude and a noise phase included in an induced noise signal obtained in the noise receiving coil to produce an adjusted noise signal having an adjusted noise amplitude and an adjusted noise phase. The adjusted noise amplitude and the adjusted noise phase are adjusted to be coincident with a noise amplitude and a noise phase contained in the receiving signal obtained in the main receiving coil, respectively. A differential circuit subtracts the adjusted noise signal from the receiving signal to cancel a noise component from the receiving signal.

Underground information collecting apparatus having a noise cancel

A method for detecting a leakage position in an impervious sheet, which comprises disposing a first and a second electrode units on an upper side and a lower side of the impervious sheet, respectively, the first electrode unit intersecting with the second electrode unit; short-circuiting all of electrodes in the first electrode unit; selecting a plurality of electrode sets one set after another set in the second electrode unit, each set comprising three electrodes adjacent to each other; supplying an AC voltage from an AC power source across a central one of each electrode set and the short circuited electrodes of the first electrode unit; measuring a potential difference between the other electrodes in the each electrode set to produce a measured voltage signal; and phase-detecting the measured voltage signal with a signal synchronized with the AC voltage from the AC power source to produce a detected signal, a series of the detected signals produced one after another changing in polarity due to a damage existing in the sheet, whereby a first position of the damage being detected on a one dimensional coordinate in an extending direction of the first electrode unit. Thereafter, the similar operation is carried out by replacing the first and the second electrode units by each other to obtain a second position of the damage on a one-dimensional coordinate in an extending direction of the second electrode unit; and defining a two-dimensional position of the damage from the first and the second positions.

Method of measuring leakage position in impervious bottom sheet using

A well data transmitting system for use in transmission of a data signal representative of a drilling parameter sensed by a sensor in a drill string of a magnetic material at a bottom of the well drilled by the drill string to a surface station mounted on the earth's surface. A carrier wave is modulated by the data signal and is then applied to a transmitting coil wound on the bottom portion of the drill string to generate a magnetic flux signal induced in the drill string material. The magnetic flux signal is picked up as an electric signal at a coil disposed around an exposed end of the drill string on the earth's surface. The electric signal is equivalent to the modulated signal and is demodulated so that the data signal can be obtained on the earth's surface. The obtained data signal is recorded in a recorder and is processed in a data processor for controlling well drilling operation. When a plurality of sensors are disposed at the well bottom, a sensor selecting signal is transmitted to the bottom as a similar magnetic flux signal through the drill string material.

Well data transmission system using a magnetic drill string for

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Tokyo, Japan

Nobuyoshi Yamazaki