GB2254441A - Magnetic flux-sensing telemetry apparatus - Google Patents
Magnetic flux-sensing telemetry apparatus Download PDFInfo
- Publication number
- GB2254441A GB2254441A GB9106808A GB9106808A GB2254441A GB 2254441 A GB2254441 A GB 2254441A GB 9106808 A GB9106808 A GB 9106808A GB 9106808 A GB9106808 A GB 9106808A GB 2254441 A GB2254441 A GB 2254441A
- Authority
- GB
- United Kingdom
- Prior art keywords
- telemetry apparatus
- transmitter
- magnetometer
- multiplexer switching
- sensor
- 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
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/0206—Three-component magnetometers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/04—Measuring direction or magnitude of magnetic fields or magnetic flux using the flux-gate principle
-
- G—PHYSICS
- G08—SIGNALLING
- G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
- G08C15/00—Arrangements characterised by the use of multiplexing for the transmission of a plurality of signals over a common path
Abstract
Telemetry apparatus comprises a transmitter having a plurality of sets (A,B,C,D,E) of arcuately distributed magnetic flux sensors; a receiver e.g. a host computer; a conductor (T) for transmission of electrical signal(s) to the receiver; and a multiplexer (Fig 3 not shown) for controlling transmission of signals. The sensors shown comprise pairs of fluxgate magnetometers (A1A2 etc). <IMAGE>
Description
TELEMETRY
Telemetry transmits from at least one transmitter to at least one receiver, electrical signal(s) comprising and/or constituting information. For the transmitting, electrical signal(s) may be transmitted from at least one transmitter to at least one receiver via at least one conductor (e.g. at least one transmission line), the number of said conductor(s) being e.g. in mathematical relationship with the number of transmitter(s) and/or the number of receiver(s). Any transmitter may comprise at least one sensor for sensing information so as to provide at least one electrical signal, which may be a "raw signal" to be processed by at least one processor. Any said processor may be comprised by at least one transmitter, or by at least one receiver, or by at least one conductor, or by any combination selected therefrom.
Any sensor may be constituted in any suitable manner, e.g.
comprise at least one magnetometer, for instance magnetometers from BARTINGTON INSTRUMENTS LTD.,
Spendlove Centre, Enstone Road, Charlbury, Oxon. OX7 3PQ,
England. Some examples of such magnetometers comprise high quality fluxgate magnetometers designated e.g. MAG01, MAG-0lH, or MAGTDM-03.
By reference, the contents of our UK patent application specification 9020569.1 are imported into the present specification.
One aspect of the present invention provides telemetry apparatus, comprising: at least one transmitter means, comprising a plurality of sets of arcuately distributed sensor means, each set comprising at least one (preferably two) respective said sensor means (optionally each comprising at least one magnetometer means, e.g. at least one fluxgate magnetometer means) for sensing magnetic flux to derive transmittable information therefrom; at least one receiver means; at least one conductor means for transmission of electrical signal(s) from said at least one transmitter means to said at least one receiver means, said conductor means optionally comprising at least one transmission line or any other suitable data and/or electrical power highway, the number of said conductor means optionally being in mathematical relationship with the number of said transmitter means and/or the number of said receiver means; and at least one multiplexer switching means for controlling said transmission of electrical signals, the number of said multiplexer switching means optionally being in mathematical relationship with the number of said transmitter means and/or the number of said receiver means and/or the number of said conductor means, preferably there being at least one respective said multiplexer switching means for or comprised by each said magnetometer means.
A second aspect of the invention provides a sensor (e.g. magnetometer) array, comprising at least one said plurality of sensor means according to the first aspect of the invention. Said array may sense components of magnetic fields. Said sensor means may be directionally sensitive. At least two of said sensor means may operate independently of each other for at least a portion of time.
Said plurality of sets of arcuately distributed sensor means may be an even or odd number, e.g. 10. Any said set may be an even or odd number at least 1 (e.g. 2) of sensor means.
Said plurality of sets of arcuately distributed sensor means be distributed in at least one plane, e.g.
coplanarly or in a puckered plane.
The arcuate spacing beween any two adjacent said sets of sensor means may change or remain the same in said plurality of sets of arcuately distributed sensor means.
Some examples of arcuate spacings (which may be in at least one plane) are pitched in the range 50 to 700, e.g.
four intervals of each substantially 600 and one interval of substantially 1200.
A fluxgate magnetomer means suitable for or comprised by a said sensor means may comprise: at least one magnetisable core; at least one magnetising conductor disposed relative to a corresponding said core such that AC current passed through said core will magnetise said core or demagnetise said core, e.g. so as to enable it to become suitably magnetically saturated or suitably magnetically unsaturated, the magnetic permeability of said core being variable in response to said AC current; and at least one inductor disposed relative to said core and said at least one conductor such that at least one electrical signal current will be induced in said at least one inductor in response to change in detectable magnetic flux density relative to time, in said core, the magnetic flux density being external and/or internal of said core.
Preferably, any magnetometer (e.g. a fluxgate magnetometer) is responsive to the three directional axes
X,Y and Z in any suitable manner(s) so that said magnetometer preferably has three independent output channels x,y,z, correponding to said axes.
Preferably, any said sensor means is or comprises respectively at least one magnetometer module comprising a magnetometer and a said multiplexer switching means.
Any said multiplexer switching means may be comprised by at least one said transmitter means (e.g. in a module containing a magnetometer), or by at least one said receiver means, or by at least one said conductor means, or by any combination selected therefrom.
Any said multiplexer switching means may comprise at least one electrical storage means (e.g. at least one capacitor) for being charged by at least one supply of current (e.g. AC or DC) such that said at least one electrical storage means will sustain or tend to sustain at least one operating function of said multiplexer switching means, and optionally thereby at least one operating function of at least one said transmitter means (e.g. at least one operating function of at least one said magnetometer means). At least one supply of current may be comprised by, or not comprised by, said telemetry apparatus of the present invention.
Telemetry apparatus of the present invention may energise or power said at least one transmitter means (e.g. power said at least one magnetometer means) via at least one corresponding said multiplexer switching means at at least one appropriate time. e.g according to a predetermined program for periodically switching on or off of said at least one supply of current to at least one said multiplexer switching means. Thus, the telemetry apparatus may time the coming onto or off of respective multiplexer switching means, whereby at least one operating function of at least one transmitter means may be synchonised, or otherwise timed, relative to at least one operating function of at least one said receiver means.
Any said at least one multiplexer switching means may enable or disable supply of electrical power to at least one said transmitter means (e.g. electrical power to magnetomer(s)) at any required time. At least one electrical signal may be transmitted via said at least one conductor means, e.g. in the absence of said electrical power. During e.g. said absence, the corresponding at least one said transmitter means may be self sustaining for at least one predetermined period of time.
Preferably, at least one said multiplexer switching means comprises: at least one electrical storage means for being charged by at least one supply of current such that said at least one electrical storage means will sustain or tend to sustain at least one operating function of said multiplexer switching means.
Said at least one electrical storage means preferably sustains or tends to sustain at least one operating function of a least one said transmitter means.
Said operating function of a least one said transmitter means may be a least one operating function of at least one said sensor means. Any operating function (e.g. an x,y or z channel) of any magnetometer means may thereby be enabled or disabled oppropriately.
Preferably, said telemetry apparatus is adapted to power said at least one transmitter means via at least one corresponding said multiplexer switching means at at least one appropriate time. Said powering is preferably according to a predetermined program for periodically switching on or off at least one supply of current to at least one said multiplexer switching means, such that said telemetry apparatus will time the coming onto or off of respective multiplexer switching means, whereby at least one operating function of a least one transmitter means may be synchronised, or otherwise timed, relative to at least one operating function of at least one said receiver means.Preferably, at least one said multiplexer switching means enables or disables supply of electrical power to at least one said transmitter means at any required time, at least one electical signal thereby being able to be transmitted via said at least one conductor means in the absence of said electrical power, such that during that absence the corresponding at least one said transmitter means may be self sustaining for at least one predetermined period of time.
In that accompanying drawings, which are by way of example:
Fig. 1 is one example of an arcuately distributed array of sets of magnetometers.
Fig. 2 is one example of an orientation tool.
Fig. 3 is one example of telemetry apparatus including the array of Fig. 1.
The drawings do not restrict the present invention, which includes all novel disclosures comprised by the present specification and its drawings.
In Fig. 1 is an array 2 of any suitable even or odd plurality (e.g. five as shown) of arcuately distributed sets (in at least one plane, e.g. coplanarly) A,B,C,D,E of independently operable magneometer modules, each set comprising respective first and second magnetometers (preferably fluxgate magnetometers) so the array has magnetomer modules Al,A2,B1 ,B2,C1 ,C2,Dl ,D2,E1,E2. Each set of magnetometers modules is disposed relative to a corresponding reference direction AR,BR,CR,DR,ER respectively. Directions AR and BR are arcuately spaced apart substantially 600 . Directions BR and CR are arcuately spaced apart substantially 600. Directions CR and DR are arcuately spaced apart substantially 600.
Directions DR and ER are arcuately spaced apart substantially 600 . Directions ER and AR are arcuately spaced apart substantially 1200. At least one of the magnetomer modules may be position adjustable, e.g. any magnetometer module may be registered relative to a portable inclinometer (not shown). This registration may register accurately a magnetometer module relative to the datum of the Y axis. A tool (Fig. 2) may be provided for enabling the registering, e.g. the tool may engage an optional spigot (not shown) on the body of a magnetometer module. The alignment tool may adopt e.g. any of four set orientations a,b,c,d, at intervals of 900 , whereby e.g.
3600 rotation of a magnetometer module with substantially 1 to 20 setting accuracy is possible even though the magnetomer module is mounted close to a surface (not shown). The magnetomer modules may be mounted by means of respective brackets, and may be aligned when clamped in the appropriate positions. Within each set of magnetometer modules, the set's two magnetomer modules may be disposed in any suitable manner relative to each other, e.g. substantially parallel as shown in Fig. 1.
In array 1, at least two magnetometer modules may each contain the same kind of magnetometer, and/or contain at least two magnetometer that may each be different kinds of magnetomers. In the drawings, each magnetomer is a fluxgate magnetometer responsive to the three directional axes X,Y, and Z (not shown) in any suitable manner(s) so that each magnetomer module has three independent output channels x,y,z corresponding to to those axes, whereby each magnetomer may provide analog output data corresponding to the independent directions of the X,Y and Z axes. Preferably, each magnetomer is the same kind of fluxgate magnetomer.
Each magnetomer module may be connected in any suitable manner(s) to any transmission means (e.g. at least one transmission line, for supplying electrical power to the magnetomers. Each magnetomer module may be connected in any suitable manner(s) to any transmission means for outputting output data from the magnetometer modules, e.g. ouput analog data for each of the x,y,z channels preferably comprised by each magnetometer module.
Each magnetometer module may have a field spliceable cable tail T, so as to be spliceable onto a respective polyurethane jacketed coaxial cable (not shown). Where it may be necessary to cut the cable, a polyweld PU and PU splice may be used. This type of splice permits rapid replacement of a magnetometer module. When cable ties are required for cable restraint, the cable ties may be of all-nylon construction, etc. and disposed at any suitable interval(s). The various magnetomer tails T are connected to a centrally located junction box, which contains control electronics e.g., corresponding to Fig.
3.
Preferably, the outputting of data from any magnetomer module is such that output data for each of the x,y,z, channels mentioned above comprise analog data transmitted by time division multiplexing, wherein timing is synchronised by intermittent removal of electrical power from any respective transmission means (e.g.
transmission line(s), for instance a coaxial cable) for supplying electrical power to the magnetomer module, whereby the power supply of each magnetomer module is maintained during absence of electrical power from the transmission means, the maintaining being provided (Fig.
3) by at least respective one electrical storage device, preferably comprising at least one capacitor contained in the magnetometer module. The electrical storage device(s) may be provided in any suitable manner(s), e.g. a magnetometer module may contain at least one electrical storage device. Thus, each magnetomer may be supplied with electrical power, and the x,y,z channels of information from each magnetomer containing those channels may be demultiplexed independently of each other.
Each magnetometer module may contain a respective said multiplexer switching means (Fig. 3).
Preferably, array 1 comprises or is coupled to the transmission lines (Fig. 3, coaxial cables) for electrically powering the magnetomer modules. The transmission lines are coupled to respective controllers 1 to 10, Fig. 3. Controllers 2 to 10 are each the same as controller 1. Electronics (Fig. 3) may be provided for e.g. onversion of time division multiplexed analog data into digital data for transmission via data lines to a host computer. Magnetic vector field strength information may be transmitted via the transmission line(s) in a time division multiplexed form from each of the x,y,z channels to the controllers. Analog data are converted into digital format by a precision 16 bit self-calibrating
A-D converter (Fig. 3).
Claims (41)
1. Telemetry apparatus, comprising: at least one transmitter means, comprising a plurality of sets of arcuately distributed sensor means, each set comprising at least one respective said sensor means for sensing magnetic flux to derive transmittable information therefrom; at least one receiver means; at least one conductor means for transmission of electrical signal(s) from said at least one transmitter means to said at least one receiver means; and at least one multiplexer switching means for controlling said transmission of electrical signals.
2. Telemetry apparatus as claimed in claim 1, wherein said plurality of sets or arcuately distributed sensor means is an even number.
3. Telemetry apparatus as claimed in claim 2, wherein said even number is 10.
4. Telemetry apparatus as claimed in claim 1, wherein said plurality of arcuately distributed sensor means is an odd number.
5. Telemetry apparatus as claimed in any one of claims 1 to 4, wherein at least one said set of arcuately distributed sensor means comprises an even number of said sensor means.
6. Telemetry apparatus as claimed in claim 5, wherein said even number of sensor means is 2.
7. Telemetry apparatus as claimed in any of claims 1 to 6, wherein the arcuate spacing between at least two adjacent said sets is in the range 50 to 700.
8. Telemetry apparatus as claimed in claim 7, wherein there are four said arcuate spacings of each substantially 600 and one said arcuate spacing of substantially 1200.
9. Telemetry apparatus as claimed in any of claims 1 to 8, wherein each said sensor means comprises at least one respective magnetometer means.
10. Telemetry apparatus as claimed in claim 9, wherein at least one said magnetometer means is at least one fluxgate magnetometer means.
11. Telemetry apparatus as claimed in claimed 10, wherein at least one said fluxgate magnetometer means comprises: at least one magnetisable core; at least one magnetising conductor disposed relative to a corresponding said core such that AC current passed through said core will magnetise said core or demagnetise said core; and at least one inductor disposed relative to said core and said at least one conductor such that at least one electrical signal current will be induced in said at least one inductor in response to change in detectable magnetic flux density relative to time, in said core, the magnetic flux density being external and/or internal of said core.
12. Telemetry apparatus as claimed in claim 11, wherein said at least one magnetising conductor is disposed relative to a corresponding said core such that AC current passed through said core will magnetise said core or demagnetise said core so as to enable it to become suitably magnetically saturated or suitably magnetically unsaturated, the magnetic permeability of said core being variable in response to said AC current.
13. Telemetry apparatus as claimed in any one of claims 9 to 12, wherein at least one said magnetometer means is responsive to three directional axes X,Y,Z so that at least one said magnetometer means has three independent output channels corresponding to said axes.
14. Telemetry apparatus as claimed in any on claims 9 to 13, wherein at least one said sensor means is or comprises respectively at least one magnetometer module comprising a magnetometer means and a said multiplexer switching means.
15. Telemetry apparatus as claimed in any one of claims 1 to 14, wherein at least one said conductor means comprises at least one transmission line and/or at least one other suitable data and/or electrical power highway.
16. Telemetry apparatus as claimed in claim 15, wherein the number of said conductor means is in mathematical relationship with the number of said transmitter means and/or the number of said receiver means.
17. Telemetry apparatus as claimed in any one of claims 1 to 16, wherein the number of said multiplexer means is in mathematical relationship with the number of said transmitter means and/or the number of said receiver means and/or the number of said conductor means.
18. Telemetry apparatus as claimed in claim 17, wherein there is at least one respective said multiplexer switching means for or comprised by each said magnetometer means.
19. Telemetry apparatus as claimed in any one of claims 1 to 18, wherein at least one said multiplexer switching means is comprised by at least one said transmitter means, or by at least one said receiver means, or by at least one said conductor means, or by any combination selected therefrom.
20. Telemetry apparatus as claimed in any one of claims 1 to 19, wherein at least one said multiplexer switching means comprises at least one electrical storage means for being charged by at least one supply of current such that said at least one electrical storage means will sustain or tend to sustain at least one operating function of said multiplexer switching means.
21. Telemetry apparatus as claimed in claim 20, wherein at least one said multiplexer switching means comprises at least one electrical storage means for being charged by at least one supply of current such that said at least one electrical storage means will sustain or tend to sustain at least one operating function of said multiplexer switching means and thereby at least one operating function of at least one said transmitter means.
22. Telemetry apparatus as claimed in claim 21, wherein said at least one operating function of at least one said transmitter means comprises at least one operating function of at least one said magnetometer means.
23. Telemetry apparatus as claimed in any one of claims 1 to 22, when adapted to energise or power said at least one transmitter means via at least one corresponding said multiplexer switching means at at least one appropriate time.
24. Telemetry apparatus as claimed in claim 23, wherein said energising or powering of said at least one transmitter means will energise or power at least one said magnetometer means.
25. Telemetry apparatus as claimed in claim 23 or 24, wherein said at least one appropriate time is according to a predetermined program for periodically switching on or off at least one said supply of current to at least one said multiplexer switching means.
26. Telemetry apparatus as claimed in any one of claims 1 to 25, wherein said telemetry apparatus is adapted to time the coming on or off of respective said multiplexer switching means, whereby at least one operating function of at least one said transmitter means may be synchronised, or otherwise timed, relative to at least one operating function of at least one said receiver means.
27. Telemetry apparatus as claimed in any one of claims 1 to 26, wherein at least one said multiplexer switching means is adapted to enable or disable supply of electrical power to at least one said transmitter means at any required time.
28. Telemetry apparatus as claimed in claim 27, wherein at least one said multiplexer switching means is adapted to enable or disable supply of electrical power to at least one said magnetometer means at any required time.
29. Telemetry apparatus as claimed in claim 28, wherein at least one electrical signal is transmittable via said at least one conductor means in the absence of said electrical power.
30. Telemetry apparatus as claimed in claim 29, wherein during said absence the corresponding at least one said transmitter means is self sustaining for at least one predetermined period of time.
31. Telemetry apparatus as claimed in any one of claims 1 to 30, wherein at least one said multiplexer switching means comprises: at least one electrical storage means for being charged by at least one supply of current such that at least one said electrical storage means will sustain or tend to sustain at least one operating function of said multiplexer switching means.
32. Telemetry apparatus as claimed in any one of claims 1 to 31, comprising at least one electrical storage means for sustaining or tending to sustain at least one operating function of at least one said transmitter means.
33. Telemetry apparatus as claimed in claim 32, wherein said at least one operating function of at least one said transmitter means is at least one operating function of at least one said sensor means, whereby at least one said operating function of at least one said magnetometer means is enabled or disabled appropriately.
34. Telemetry apparatus as claimed in any one of claims 1 to 33, adapted to power at least one said transmitter means via at least one corresponding said multiplexer switching means at at least one appropriate time, said powering being according to a predetermined program for periodically switching on or off at least one supply of current to at least one said multiplexer switching means, such that said telemetry apparatus will time the coming on or off of respective said multiplexer switching means, whereby at least one operating function of at least one said transmitter means will be synchronised, or otherwise timed, relative to at least one operating function of at least one said receiver means; and at least one said multiplexer switching means will enable or disable supply of electrical power to at least one said transmitter means at any required time, at least one electrical signal thereby being able to be transmitted via said at least one conductor means in the absence of said electrical power, such that during that absence the corresponding at least one said transmitter means will be self sustaining for at least one predetermined period of time.
35. Telemetry apparatus, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
36. A sensor array, comprising at least one plurality of said sensor means according to any one of claims 1 to 35.
37. A sensor array as claimed in claim 36, wherein said array is adapted to sense components of magnetic fields.
38. A sensor array as claimed in claim 36 or 37, wherein said plurality of sensor means is directionally sensitive.
39. A sensor array as claimed in any one of claims 36 to 38, wherein at least two said sensor means are adapted to operate independently of each other for at least a portion of time.
40. A sensor array substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
41. Sensor/telemetry apparatus, comprising: telemetry apparatus as claimed in any one of claims 1 to 35; and a sensor array as claimed in any one of claims 36 to 40.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9106808A GB2254441B (en) | 1991-04-02 | 1991-04-02 | Telemetry |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9106808A GB2254441B (en) | 1991-04-02 | 1991-04-02 | Telemetry |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9106808D0 GB9106808D0 (en) | 1991-05-22 |
| GB2254441A true GB2254441A (en) | 1992-10-07 |
| GB2254441B GB2254441B (en) | 1995-10-04 |
Family
ID=10692465
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9106808A Expired - Lifetime GB2254441B (en) | 1991-04-02 | 1991-04-02 | Telemetry |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2254441B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2401983A (en) * | 2003-04-09 | 2004-11-24 | Powergraphic Displays Ltd | Illuminated display apparatus |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1543895A (en) * | 1976-02-19 | 1979-04-11 | Thomsen I | Detector for detecting the angular position of a rotatable magnet |
| GB2118305A (en) * | 1982-01-21 | 1983-10-26 | Cornell Res Foundation Inc | Method and apparatus for extended lateral range electrical conductivity logging |
| GB2132769A (en) * | 1982-11-22 | 1984-07-11 | Gearhart Ind Inc | Method and apparatus for borehole logging |
| GB2158950A (en) * | 1984-05-15 | 1985-11-20 | Petroles Cie Francaise | Magnetic exploration apparatus for a well hole |
| US4599564A (en) * | 1983-11-07 | 1986-07-08 | Rca Corporation | Tubular semiconductor magnetic field sensor and circuits for use therewith |
| GB2176009A (en) * | 1985-03-29 | 1986-12-10 | Vmei Lenin Nis | Magnetic field intensity meter |
| GB2236399A (en) * | 1989-09-22 | 1991-04-03 | Bartington Instr Ltd | Telemetry apparatus for magnetic flux sensors |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3835375A (en) * | 1972-01-21 | 1974-09-10 | L Rovner | Apparatus for determining the direction of a magnetic field relative to a reference direction by synchronously scanning the field and a memory |
| US3781664A (en) * | 1972-10-24 | 1973-12-25 | Develco | Magnetic detection for an anti-shoplifting system utilizing combined magnetometer and gradiometer signals |
| DE3247585A1 (en) * | 1982-12-22 | 1984-06-28 | Siemens AG, 1000 Berlin und 8000 München | MULTI-CHANNEL DEVICE FOR MEASURING DIFFERENT FIELD SOURCES OF LOW MAGNETIC FIELDS |
| DE3324208A1 (en) * | 1983-07-05 | 1985-01-17 | Siemens AG, 1000 Berlin und 8000 München | SUPRAL-CONDUCTING GRADIOMETER COIL SYSTEM FOR A DEVICE FOR MULTI-CHANNEL MEASUREMENT OF WEAK, CHANGING MAGNETIC FIELDS |
| GB2171523B (en) * | 1985-02-23 | 1988-03-09 | Stc Plc | Magnetic gradient detection |
-
1991
- 1991-04-02 GB GB9106808A patent/GB2254441B/en not_active Expired - Lifetime
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1543895A (en) * | 1976-02-19 | 1979-04-11 | Thomsen I | Detector for detecting the angular position of a rotatable magnet |
| GB2118305A (en) * | 1982-01-21 | 1983-10-26 | Cornell Res Foundation Inc | Method and apparatus for extended lateral range electrical conductivity logging |
| GB2132769A (en) * | 1982-11-22 | 1984-07-11 | Gearhart Ind Inc | Method and apparatus for borehole logging |
| US4599564A (en) * | 1983-11-07 | 1986-07-08 | Rca Corporation | Tubular semiconductor magnetic field sensor and circuits for use therewith |
| GB2158950A (en) * | 1984-05-15 | 1985-11-20 | Petroles Cie Francaise | Magnetic exploration apparatus for a well hole |
| GB2176009A (en) * | 1985-03-29 | 1986-12-10 | Vmei Lenin Nis | Magnetic field intensity meter |
| GB2236399A (en) * | 1989-09-22 | 1991-04-03 | Bartington Instr Ltd | Telemetry apparatus for magnetic flux sensors |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2401983A (en) * | 2003-04-09 | 2004-11-24 | Powergraphic Displays Ltd | Illuminated display apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9106808D0 (en) | 1991-05-22 |
| GB2254441B (en) | 1995-10-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PE20 | Patent expired after termination of 20 years |
Expiry date: 20110401 |