+RAD Dad Posted March 21, 2002 Share Posted March 21, 2002 How do electronic Compas' work? How reliable are they? Thanks for the help for this dumb newbe ummmm....not sure what to say here....so ummm, well errrr, uhhhh, well I guess that's it. Quote Link to comment
Couch_Potato Posted March 21, 2002 Share Posted March 21, 2002 quote:How do electronic Compas' work? How reliable are they? I was wondering this myself so I did a search and found the following at BoatUS.com: quote:The source of magnetic heading information in electronic form on most recreational vessels is supplied by a sensor system called a magnetic flux gate. The typical flux gate is comprised of a core of easily magnetized metal on which four coils of fine wire have been wound. An AC voltage is applied to one of the coils. The relative magnitude of the voltage induced in each of the other coils will depend on the angle of each coil to the earth's magnetic field. The magnetic heading information supplied will be accurate as long as the coil assembly is parallel to the earth's surface. For this reason, the coil assembly is usually suspended in a housing, which may, like many compasses, be filled with light oil to dampen its movements . . . Unlike conventional compasses which require manual adjustment to compensate for local magnetic fields, most flux gate systems can be automatically compensated often by pressing a button and performing a 540 to 720 degree turn in one direction in a period of from two to three minutes. The compensation procedure can be repeated whenever the user suspects that a change may have occurred in the local magnetic environment. These flux gate or flux detector compasses are quite accurate, however they do suffer from the same errors that occur with conventional compassses. In the northern hemisphere they are least accurate on headings close to north, most accurate on headings close to south (with the reverse true in the southern hemisphere). They can provide momentarily misleading heading information on east or west headings when subject to rapid acceleration or deceleration . . . Rapid turns can create time lag errors, it takes a moment for the system to catch up . . . I thought it was something like that Mike Quote Link to comment
Couch_Potato Posted March 21, 2002 Share Posted March 21, 2002 quote:How do electronic Compas' work? How reliable are they? I was wondering this myself so I did a search and found the following at BoatUS.com: quote:The source of magnetic heading information in electronic form on most recreational vessels is supplied by a sensor system called a magnetic flux gate. The typical flux gate is comprised of a core of easily magnetized metal on which four coils of fine wire have been wound. An AC voltage is applied to one of the coils. The relative magnitude of the voltage induced in each of the other coils will depend on the angle of each coil to the earth's magnetic field. The magnetic heading information supplied will be accurate as long as the coil assembly is parallel to the earth's surface. For this reason, the coil assembly is usually suspended in a housing, which may, like many compasses, be filled with light oil to dampen its movements . . . Unlike conventional compasses which require manual adjustment to compensate for local magnetic fields, most flux gate systems can be automatically compensated often by pressing a button and performing a 540 to 720 degree turn in one direction in a period of from two to three minutes. The compensation procedure can be repeated whenever the user suspects that a change may have occurred in the local magnetic environment. These flux gate or flux detector compasses are quite accurate, however they do suffer from the same errors that occur with conventional compassses. In the northern hemisphere they are least accurate on headings close to north, most accurate on headings close to south (with the reverse true in the southern hemisphere). They can provide momentarily misleading heading information on east or west headings when subject to rapid acceleration or deceleration . . . Rapid turns can create time lag errors, it takes a moment for the system to catch up . . . I thought it was something like that Mike Quote Link to comment
+RAD Dad Posted March 21, 2002 Author Share Posted March 21, 2002 Hmmm, sounds complicated. So what about these handheld electronic compas' or even the electronic compas' you can find in some watches? Anyone know any more, and maybe have a little more laymens way of explaining it all? ummmm....not sure what to say here....so ummm, well errrr, uhhhh, well I guess that's it. Quote Link to comment
+Prime Suspect Posted March 21, 2002 Share Posted March 21, 2002 quote:Originally posted by RAD Dad: Hmmm, sounds complicated. So what about these handheld electronic compas' or even the electronic compas' you can find in some watches? Anyone know any more, and maybe have a little more laymens way of explaining it all? My Suunto watch is supposed to be accurate to with a degree or two. It has a bubble level built into the watch, to ensure you're holding it level when taking a reading. Quote Link to comment
Couch_Potato Posted March 21, 2002 Share Posted March 21, 2002 Ok, let me try to 'splain it a bit. The electonic compass uses a ferrite core material (metal or magnetic ceramic) to magnetically couple 4 coils of wire along different axes. One of those coils has an AC current applied to it to create a known magnetic field. The compass then measures the current induced on the other 3 coils due to magnetic coupling. The amount of coupling and therefore the amount of current induced is a function of the orientation of each individual coil to the earth's magnetic field. North can be determined by the amount of current from each of the 3 coils. Another way to think of it is that the electronic compass creates a local magnetic field and then measures how that local field interacts with the earth's magnetic field and thus determine the orientation of the earth's magnetic field. This type of measurement works best when the axes of the coils is co-planar with the field that you're trying to measure. For the earth's field that typically means that the device must stay parallel to the surface of the earth. Thus the level in the watch. The coils that induce and measure the magnetic fields don't necessarily have to be large. I imagine that an electronic compass setup could be designed to fit within a wristwatch and I'm positive that palm - sized units are available. Any clearer? Mik [This message was edited by mvwood on March 21, 2002 at 08:15 PM.] Quote Link to comment
Couch_Potato Posted March 21, 2002 Share Posted March 21, 2002 Ok, let me try to 'splain it a bit. The electonic compass uses a ferrite core material (metal or magnetic ceramic) to magnetically couple 4 coils of wire along different axes. One of those coils has an AC current applied to it to create a known magnetic field. The compass then measures the current induced on the other 3 coils due to magnetic coupling. The amount of coupling and therefore the amount of current induced is a function of the orientation of each individual coil to the earth's magnetic field. North can be determined by the amount of current from each of the 3 coils. Another way to think of it is that the electronic compass creates a local magnetic field and then measures how that local field interacts with the earth's magnetic field and thus determine the orientation of the earth's magnetic field. This type of measurement works best when the axes of the coils is co-planar with the field that you're trying to measure. For the earth's field that typically means that the device must stay parallel to the surface of the earth. Thus the level in the watch. The coils that induce and measure the magnetic fields don't necessarily have to be large. I imagine that an electronic compass setup could be designed to fit within a wristwatch and I'm positive that palm - sized units are available. Any clearer? Mik [This message was edited by mvwood on March 21, 2002 at 08:15 PM.] Quote Link to comment
+RAD Dad Posted March 22, 2002 Author Share Posted March 22, 2002 Ok....I think I get it now. ummmm....not sure what to say here....so ummm, well errrr, uhhhh, well I guess that's it. Quote Link to comment
+Brokenwing Posted March 22, 2002 Share Posted March 22, 2002 How does an electronic compass work? Why, electronically, of course! Scott / Brokenwing http://www.cordianet.com/geocaching Quote Link to comment
+Brokenwing Posted March 22, 2002 Share Posted March 22, 2002 How does an electronic compass work? Why, electronically, of course! Scott / Brokenwing http://www.cordianet.com/geocaching Quote Link to comment
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