Talk:Magnetometer

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ESR and NMR Sections

The electron spin resonance sections of this article has absolutetly nothing to do with magnetometers. The NMR section was also way beyond the scope of this article, and in the context of this article made very little since. The last part of the NMR section had some relevance to magnetometers, and so was merged with the previous section.

It seems though that it's a bit redundant -- so perhaps someone should just remove that passage too.

Anyone interested in ESR and NMR can certainly visit the respective articles.

Mobile phones

Deleted the passage regarding mobile phones as it read like an advertisement for one specific brand and model of cel phone. If anyone cared to write a proper description of cel/mobile phones and magnetometers, that would be great. There are several phones on the market that make use of these, and they came about way before the Motorola Droid as well. —Preceding unsigned comment added by 93.139.116.91 (talk) 11:23, 26 November 2009 (UTC)[reply]

Space probe?

Since I reached this article by way of an article on a space probe, it would seem that the description should be amended to say that a magnetometer measures magnetic fields associated with planetary objects. Perhaps a linkage to other articles about space probes would be a good idea too.

== Space-Based Magnetometers and Magnetometer Arrays --

There are many space-based magnetometers for a wide variety of purposes. Earth-based magnetometer arrays are routinely correlated with satellite-based magnetometers to study lithospheric-atmospheric, lithospheric-ionospheric interactions. I was surprised to see that search coil magnetometers were not mentioned. These three-axis magnetometers (see Themis satellite) are extremely sensitive and "broadband" covering the range roughly from 1 millihertz to 1 khz. The ULF sensors collectively are used now for seismo-electromagnetic monitoring of earthquakes. All the magnetospheric research is magnetometer based.

Orbiting and geostationary satellites routinely carry three-axis magnetometers. These can "see" the earth magnetically to track earthquakes, thunderstorms, the ionosphere and human-generated magnetic fields. The first instruments sent to most solar system bodies are magnetometers. The moon, venus, mars and the sun all have magnetic fields which have been measured with magnetometers. InternetFoundation (talk) 23:02, 2 April 2009 (UTC)Internet Foundation[reply]

Metal detector

Isn't a Magnetometer the basis for the airport metal detectors? If so, shouldn't that be included within this article? Vegaswikian 09:10, 12 October 2005 (UTC)[reply]

Whilst I am no expert in airport securiyu, I beleive they use induction loop systems as they do for the hand-held units beacause magnetomers do not detect non-ferrous material. The fact the coins set of some detectrors is proof that these ones are not magnetometers.

In geophysical parlance, we would lump aiport metal detectors in with EM systems - not magnetometers. That said, magneotmeters can be used in some low frequence EM sensing applications such as SQUIDS in borehole conductivity systems and in magneto tellurics, so there is some overlap.

Detailed discussion may be beyond the scope in the magnetometer section. There is a lot of confusion by the gweneral pulic about magneotmeters and metal detectors. As a manufacturer of magneotmeters for a decade, I can get tired of continuall explaining the dufferences - especially when they think thy have similar privce tags. I have tried to address the difference in simple terms in the section I added Magnetometers vs Metal Detectors. Phil

Magnetogram

If you're reading this article and know about magnetograms, would you be able to expand that article? Rob 17:08, 11 March 2006 (UTC)[reply]

As a geophysicist using magnetometers for over 20 years, with some involvement with obervatories, I have never head of a magnetogram. Sounds like something pseudo medical, 'pianola role' or 'dinousaur' kind of magneotmeter ?

If so, maybe this could go into the history of magneotmeters along with a nice photo. Phil —Preceding undated comment added 07:59, 16 June 2011 (UTC).[reply]

Attitude control and magnetometers

The open source apeliotes project uses 3 magnetometers mounted orthogonaly to determine an aircrafts attitude about 2 axis. While this seems obvious they don't seem to have been used to determine 2 angles in this way before. They are normally used to just determine heading, not pitch or roll.

Copyright violation?

Text from this article was found verbatim here: http://en.allexperts.com/e/m/ma/magnetometer.htm I don't know who stole from whom or what the rules are; I'm not an active member of Wikipedia...

They copied us - if you scroll all the way down to the small print at the bottom of the page there's a credit. Natalie 03:48, 26 March 2007 (UTC)[reply]

That's one of the many sites that lives by copying wikipedia content and adding advertisements. All perfectly acceptable; ignore them. Dicklyon 03:57, 26 March 2007 (UTC)[reply]

Nuclear Magnetic Resonance (NMR) reference

Proton Precession Magnetometers and Overhauser Magnetometers both utilise NMR effects. I suggest updating the article to reflect this, and tying in with the NMR article, which does not mention the relationship either. GilesW 10:53, 19 April 2007 (UTC)[reply]

Done, but Wiki article on EFNMR is needed, can anyone help please? GilesW 08:44, 20 May 2007 (UTC)[reply]

EFNMR article started and link added. GilesW 22:32, 26 May 2007 (UTC)[reply]

I agree - my livihood for the last 10 years has been from NRM magnetometers. NMR is a difficult concept for many people to grasp. I will consider re-writing both sections with permission to use material from manuals by companies like GEM Systems. Geometrics also has some excellent material on proton.Phil — Preceding unsigned comment added by Magman5 (talk • contribs) 08:05, 16 June 2011 (UTC)[reply]

Laboratory magnetometers

This article deals only with survey applications. Magnetometers are also used for laboratory measurements in rock magnetism studies, engineering, etc. I don't know enough about the various lab applications to write about them, but perhaps someone out there can. Tapatio 16:49, 4 July 2007 (UTC)[reply]

SI Notation

Is there a preference for quoting the proton magnetogyric ratio as: 0.042576 Hz / nT rather than 42.576 Hz / μT, in accordance with SI standards?

Or is this a work-around to avoid the use of the symbol μ? GilesW 13:55, 19 September 2007 (UTC)[reply]

I do not see, how Hz/nT is less SI conform than Hz/μT, but I do agree that the given number looks quite ugly, and therefore might be considered as bad style. Maybe the original author was a Geophysicist, and therefore familiar with typical Geophysical field instruments and their manuals. They tend to almost exclusively use nT instead of μT, since nT is the quantity usually used to display and record the final measurement results. This is due to the fact that nT better reflect the order of magnitude of typical observed anomalies, as well as the measurement's accuracy. However, since the two numbers are equivalent, which one is finally kept in the article should not really matter. Space2Core (talk) 17:42, 17 February 2009 (UTC)[reply]

Incorrect comment about atomic magnetometers?

Under the Cesium vapor magnetometer section, it says "when removed from an isolated environment, the cesium vapour can never be 'perfectly' calibrated and the system is subject to environmental interference as are all scalar magnetometers," which seems to completely go counter to what I know about magnetometers that use optical pumping in one way or another.

I am more familiar with magnetometers with modulated pump light(I worked on ones based on amplitude-modulated NMOR effect one summer), but as I understand it, atomic magnetometers do not need to be calibrated---it measures the true local magnetic field, measured as the Larmor precession frequency of the atom (which can be calculated, if the gyromagnetic ratio of the particular isotope species is known).

As I understand, this is a completely different case with other magnetometers like fluxgates or SQUIDS that actually measure flux, rather than magnetic field and do need to be calibrated to the magnetic field somehow.

So, which is right---what I thought I knew, or what a section of the article seems to be saying about all atomic (and usually scalar) magnetometers? novakyu (talk) 06:11, 15 December 2007 (UTC)[reply]

Three or four paragraphs are replicated - and exact cut and paste text from a GEM Systems PDF

Search the phrase "The Overhauser effect takes advantage". Below the heading "Overhauser magnetometer" you will find about 3 or 4 paragraphs that are word for word identical. ie accidentally repeated. Dave3457 (talk) 05:53, 17 February 2009 (UTC)[reply]

I think the reason you're seeing redundant text is because someone has cut and paste the text from http://www.gemsys.ca/PDFDocs/GEM_Overhauser_Magnetometers_Short_Overview.pdf in a rather haphazard manner. There is no copyright mentioned in the PDF itself, but it might be a good idea to get a description of the device from somewhere other than a manufacturer's brochure about it. All the Overhauser Magnetometer text appears to come from this one source, without citation or credit.

--Gldm 3/3/2009

Looks extremely close to [1] and [2]. Went back and forth between the {{copyvio}} and {{copypaste}} tag. Went {{copypaste}} for now, but {{copyvio}} is probably the correct tag... Jheiv (talk) 13:19, 5 March 2009 (UTC)[reply]

Copyright problem removed

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Comparison of types

A comparison of the measurement ranges and noise would be very useful. For instance, very little is said about Hall sensors, when they are surely the most commonly used in the world (floppy drive motors use them, likely hard drive motors, printers, gear teeth detectors, etc.) Also, what about GMR sensors? Not all magnetometers are esoteric laboratory instruments. Often one just wants to measure the strength of a magnetic field from a magnet or other high-field source. There is no mention of these instruments. 76.215.209.21 (talk) 08:41, 11 April 2009 (UTC)[reply]

Agreed. I think a table should be added with the following columns. [Technology],[Typical Noise T/rtHz],[Best Case Noise],[Freq Response], [Cost] 150.101.188.135 (talk) 23:36, 15 April 2010 (UTC)[reply]

mobile phones

I believe the list of models that contain magnetometers should be sorted in chronological order (i.e. which was the 1st model which embedded a magnetometer and to my knowledge HTC dream (known as T-mobile G1 in the US) was one of the 1st ones. If anybody knows more info about the order in which these devices appeared please sort the list accordingly. The HTC Dream was release before the iphone 3GS and thus deserves to be mentioned first. One could maybe argue that the list should be sorted by popularity but I believe chronological is more fair. —Preceding unsigned comment added by Jubeidono (talk • contribs) 03:12, 28 February 2010 (UTC)[reply]

what cause earth magnitism?

there are large no. of matels in side the earth which are form in the present of the molten state. as the earth rotate on its daily rotation the ions of the molten metals are of +ve and -ve charge and on rotating on ie the generation of the magnetic field takes place. according to orestate that when current is generated the magnetic field is generated.. —Preceding unsigned comment added by 115.242.127.42 (talk) 11:13, 29 May 2010 (UTC)[reply]

What about Induction Magnetometers?

There is another type of magnetometer, the induction magnetometer, which is essentially a ferrite rod wound with many thousands of turns of magnet wire, which measures changes in the magnetic field by the emf induced in the coil. High impedance op amp circuits (or sometimes a Sutton "negative impedance" amplifier) are employed to detect and amplify the signals.

It is very sensitive and can measure field changes down to pico-Tesla levels.

Such a magnetometer is currently deployed at the HAARP site in Alaska. http://137.229.36.30/cgi-bin/scmag/disp-scmag.cgi http://www.haarp.alaska.edu/haarp/magind.html http://www.haarp.alaska.edu/haarp/images/diag/imSensor.jpg

Should this kind of instrument be included in this article?

Jdagius (talk) 22:02, 17 October 2010 (UTC)[reply]

Yes they should be included with mention of their strengths and weaknesses and applications.--Magman5 (talk) 08:12, 16 June 2011 (UTC)[reply]