Detector for detecting a buried current carrying conductor

• US 20070018632A1
• Filed: 06/20/2006
• Published: 01/25/2007
• Est. Priority Date: 06/20/2005
• Status: Active Grant

• Current Assignee: Radiodetection Limited
• Original Assignee: Radiodetection Limited
• Inventors: Royle, John
• Granted Patent: US 7,847,556 B2
• Time in Patent Office: Days
• US Class Current: 324/67
• CPC Class Codes: G01V 3/081 the magnetic field is produced by the objects or geological structures characterised by the method of magnetic field measurement G01R33/00

Abstract

A detector 1 for detecting a buried current carrying conductor comprises a digital homodyne receiver. The receiver processes field strength signals induced in a pair of vertically spaced antennae 3, 5. The analogue to digital converter is an audio-grade stereo CODEC 11.

Claims

1. A detector for detecting a buried current carrying conductor, comprising:

two magnetic sensors, each magnetic sensor for converting electromagnetic radiation from the conductor into a field strength signal;

an analogue to digital converter arranged to convert the field strength signals into digital signals; and

a digital signal processor arranged to process the digital signals and to isolate signals of predetermined frequency bands;

wherein the digital signal processor is programmed to process the digital signals in their baseband.

2. A detector as claimed in claim 1, wherein the analogue to digital converter is a delta-sigma converter.

3. A detector as claimed in claim 2, wherein the analogue to digital converter is a stereo CODEC.

4. A detector as claimed in claim 1, wherein each of the magnetic sensors has a noise floor and the field strength signals are input to an amplifier, to lift the magnetic sensor noise floor above an intrinsic quantisation noise of the analogue to digital converter referred to the bandwidth of one or more of the predetermined frequency bands, the output of the amplifier being provided as an input to the analogue to digital converter.

5. A detector as claimed in claim 1, wherein there are no selective filtering means, multiple switch gain stages and/or a phase sensitive heterodyne circuit between the magnetic sensor and the analogue to digital converter.

6. A detector as claimed in claim 1, wherein the digital signal processor is programmed to process signals from each magnetic sensor in two or more frequency bands simultaneously, those bands being selected from:

(i) very low frequency band;

(ii) mains electricity frequency band; and

(iii) a predetermined frequency band produced by a dedicated signal transmitter for a detector for detecting a current carrying conductor.

7. A detector as claimed in claim 6, wherein the digital signal processor is programmed to process signals from each magnetic sensor in three frequency bands simultaneously.