GB2004069A - Improvements in or relating to metal detectors - Google Patents
Improvements in or relating to metal detectorsInfo
- Publication number
- GB2004069A GB2004069A GB7832419A GB7832419A GB2004069A GB 2004069 A GB2004069 A GB 2004069A GB 7832419 A GB7832419 A GB 7832419A GB 7832419 A GB7832419 A GB 7832419A GB 2004069 A GB2004069 A GB 2004069A
- Authority
- GB
- United Kingdom
- Prior art keywords
- signals
- comparator
- amplifier
- mixer
- frequency
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/08—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices
- G01V3/10—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils
- G01V3/104—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils using several coupled or uncoupled coils
- G01V3/105—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils using several coupled or uncoupled coils forming directly coupled primary and secondary coils or loops
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Remote Sensing (AREA)
- Life Sciences & Earth Sciences (AREA)
- Electromagnetism (AREA)
- Environmental & Geological Engineering (AREA)
- Geology (AREA)
- General Life Sciences & Earth Sciences (AREA)
- General Physics & Mathematics (AREA)
- Geophysics (AREA)
- Geophysics And Detection Of Objects (AREA)
Abstract
In a metal detector which utilises two different frequencies ground signals are substantially cancelled so as to improve the sensitivity of the metal detector. Transmitter coil 1a is fed with frequency f1 of 1Kc/s to 100Kc/s and f2 ten times as great and the induced signal in receiver coil 1b is fed via diplexer 5 over two channels each including amplifier 8,9 mixer 10,11, filter 12,13 to comparator 14. The gain of amplifier 9 is adjusted relative to amplifier 8 in accordance with the ratio f1/f2 so that the output signals at 12,13 are substantially equal for the ground signals and these cancel out in comparator 14. The signals due to the metal object have similar amplitudes at the two frequencies and due to the different gains of 8 and 9 an unbalance signal is produced by comparator 14. Signals originating from ferrite materials may be cancelled in the low frequency path by feeding an L.O. frequency, the phase of which is controlled by means of a feedback loop, to mixer 11. <IMAGE>
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7832419A GB2004069B (en) | 1977-08-20 | 1978-08-07 | Metal detectors |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB3501477 | 1977-08-20 | ||
| GB7832419A GB2004069B (en) | 1977-08-20 | 1978-08-07 | Metal detectors |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2004069A true GB2004069A (en) | 1979-03-21 |
| GB2004069B GB2004069B (en) | 1982-04-21 |
Family
ID=26262543
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7832419A Expired GB2004069B (en) | 1977-08-20 | 1978-08-07 | Metal detectors |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2004069B (en) |
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2481459A1 (en) * | 1980-04-29 | 1981-10-30 | Electrolocation Ltd | DEVICE FOR DETECTING CONCEALED CURRENT CONDUCTORS, SUCH AS BURST CABLES OR CONDUITS, INTENDED FOR IMPROVEMENT OF RECOVERY INSTRUMENTS |
| EP0091034A2 (en) * | 1982-04-01 | 1983-10-12 | Asea Ab | Arrangement for the detection of metallic objects in a flow of material |
| US4503392A (en) * | 1981-07-21 | 1985-03-05 | Rizhsky Politekhnichesky Institut | Apparatus for non-destructive testing of spot welds using an electromagnetic field |
| GB2194055A (en) * | 1986-08-15 | 1988-02-24 | Outokumpu Oy | Metal detector with compensation circuit for improving signal/interference ratio |
| US4942360A (en) * | 1986-09-08 | 1990-07-17 | Candy Bruce H | A method and apparatus of discrimination detection using multiple frequencies to determine a recognizable profile of an undesirable substance |
| US5039946A (en) * | 1990-02-26 | 1991-08-13 | Inzhenerny Tsentr Vnii Po Stroitelstvu Magistralnykh Truboprovodov | Metalliferous objects detector having a pair of angularly positioned driving loops and a pair of parallel, coaxial receiving loops |
| US5506506A (en) * | 1992-01-14 | 1996-04-09 | Halcro Nominees Pty Ltd. | Metal detector for detecting and discriminating between ferrous and non-ferrous targets in ground |
| EP0844499A2 (en) * | 1996-11-26 | 1998-05-27 | Institut Dr. Friedrich Förster Prüfgerätebau GmbH & Co. KG | Method for operating and signal processing of an eddy-current probe and apparatus for carrying out this method |
| WO2003071311A1 (en) * | 2002-02-19 | 2003-08-28 | Radiodetection Limited | System and method for detecting a concealed current carrying conductor |
| WO2006136779A1 (en) * | 2005-06-20 | 2006-12-28 | Radiodetection Limited | A method of and apparatus for determining if a buried current carrying conductor is buried above a predetermined minimum depth |
| US7649356B2 (en) | 2002-12-18 | 2010-01-19 | White's Electronics, Inc. | Pulse induction metal detector having high energy efficiency and sensitivity |
| US8278918B2 (en) | 2010-10-07 | 2012-10-02 | Mettler-Toledo Safeline Limited | Method for operating of a metal detection system and metal detection system |
| US8314713B2 (en) | 2010-10-07 | 2012-11-20 | Mettler-Toledo Safeline Limited | Method for monitoring the operation of a metal detection system and metal detection system |
| US8587301B2 (en) | 2010-10-07 | 2013-11-19 | Mettler-Toledo Safeline Limited | Method for operating a metal detection system and metal detection system |
| US9018935B2 (en) | 2011-09-19 | 2015-04-28 | Mettler-Toledo Safeline Limited | Method for operating a metal detection apparatus and apparatus |
-
1978
- 1978-08-07 GB GB7832419A patent/GB2004069B/en not_active Expired
Cited By (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2481459A1 (en) * | 1980-04-29 | 1981-10-30 | Electrolocation Ltd | DEVICE FOR DETECTING CONCEALED CURRENT CONDUCTORS, SUCH AS BURST CABLES OR CONDUITS, INTENDED FOR IMPROVEMENT OF RECOVERY INSTRUMENTS |
| US4503392A (en) * | 1981-07-21 | 1985-03-05 | Rizhsky Politekhnichesky Institut | Apparatus for non-destructive testing of spot welds using an electromagnetic field |
| EP0091034A2 (en) * | 1982-04-01 | 1983-10-12 | Asea Ab | Arrangement for the detection of metallic objects in a flow of material |
| EP0091034A3 (en) * | 1982-04-01 | 1984-09-05 | Asea Ab | Arrangement for the detection of metallic objects in a flow of material |
| GB2194055A (en) * | 1986-08-15 | 1988-02-24 | Outokumpu Oy | Metal detector with compensation circuit for improving signal/interference ratio |
| GB2194055B (en) * | 1986-08-15 | 1991-01-30 | Outokumpu Oy | Method and apparatus for detecting metal objects |
| US4942360A (en) * | 1986-09-08 | 1990-07-17 | Candy Bruce H | A method and apparatus of discrimination detection using multiple frequencies to determine a recognizable profile of an undesirable substance |
| US5039946A (en) * | 1990-02-26 | 1991-08-13 | Inzhenerny Tsentr Vnii Po Stroitelstvu Magistralnykh Truboprovodov | Metalliferous objects detector having a pair of angularly positioned driving loops and a pair of parallel, coaxial receiving loops |
| US5506506A (en) * | 1992-01-14 | 1996-04-09 | Halcro Nominees Pty Ltd. | Metal detector for detecting and discriminating between ferrous and non-ferrous targets in ground |
| EP0844499A3 (en) * | 1996-11-26 | 1999-04-14 | Institut Dr. Friedrich Förster Prüfgerätebau GmbH & Co. KG | Method for operating and signal processing of an eddy-current probe and apparatus for carrying out this method |
| EP0844499A2 (en) * | 1996-11-26 | 1998-05-27 | Institut Dr. Friedrich Förster Prüfgerätebau GmbH & Co. KG | Method for operating and signal processing of an eddy-current probe and apparatus for carrying out this method |
| US6005392A (en) * | 1996-11-26 | 1999-12-21 | Institut Dr. Friedrich Foerster Pruefgeraetebau Gmbh & Co. Kg | Method for the operation and for the evaluation of signals from an eddy current probe and device for performing the method |
| WO2003071311A1 (en) * | 2002-02-19 | 2003-08-28 | Radiodetection Limited | System and method for detecting a concealed current carrying conductor |
| US6777923B2 (en) | 2002-02-19 | 2004-08-17 | Radiodetection Limited | System and method for detecting a concealed current carrying conductor |
| US7649356B2 (en) | 2002-12-18 | 2010-01-19 | White's Electronics, Inc. | Pulse induction metal detector having high energy efficiency and sensitivity |
| WO2006136779A1 (en) * | 2005-06-20 | 2006-12-28 | Radiodetection Limited | A method of and apparatus for determining if a buried current carrying conductor is buried above a predetermined minimum depth |
| CN101248372B (en) * | 2005-06-20 | 2012-03-21 | 无线电探测有限公司 | A method of and apparatus for determining if a buried current carrying conductor is buried above a predetermined minimum depth |
| US8278918B2 (en) | 2010-10-07 | 2012-10-02 | Mettler-Toledo Safeline Limited | Method for operating of a metal detection system and metal detection system |
| US8314713B2 (en) | 2010-10-07 | 2012-11-20 | Mettler-Toledo Safeline Limited | Method for monitoring the operation of a metal detection system and metal detection system |
| US8587301B2 (en) | 2010-10-07 | 2013-11-19 | Mettler-Toledo Safeline Limited | Method for operating a metal detection system and metal detection system |
| US9018935B2 (en) | 2011-09-19 | 2015-04-28 | Mettler-Toledo Safeline Limited | Method for operating a metal detection apparatus and apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2004069B (en) | 1982-04-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19920807 |