Perhaps there is a little bit of Boy Scout in all of us. A Compass in Every Smartphone tells there is a growing demand from consumers for an electronic compass in their smartphones. Many phones like my Blackberry, have a GPS chip, but that only provides location. It doesn't know which way I am pointing. With a little bit of software, it can sort of average out the direction I'm traveling by the change in location, but it isn't very accurate - the compass angle typically swings erratically when I'm walking. What is an Electronic Compass explains this in a little more detail.
The IEEE Spectrum article tells that semiconductor manufacturers are producing better three-axis memory field detectors and the price has dropped below $0.50 per unit. One of the manufacturers, MEMSIC, has an application note on magnetometer fundamentals. The principle behind their product is anisotropic magnetoresistive (AMR) sensors, which are resistors that change in the presence of a magnetic field. By arranging the resistors in two or three axes, a wheatstone bridge can determine minute magnetic field changes.
Another type of technology, the Hall Effect, can also be used to detect magnetic fields. The magnetoresistive advocates claim that their technology requires much less battery power, important for smartphone owners.
Wiki explains that the Earth's magnetic field can be modeled as a magnetic dipole with poles approximately close to the Earth's geographic poles. The intensity of the magnetic field is varies relative to angle between the two poles. The minute intensity variance between the resistors mounted orthogonal to each other is what electronic compasses detect.
Silicon Magnetic Sensor Market Offers Attractive Growth tells the products were valued at $821M last year, but should almost double in less than five years. Only 10 percent of the market was for smartphones, but that will increase to 33 percent within three years.
{LIFTOFF!
Mon, 08 Feb
2010 04:14:27 AM EST
Endeavour has cleared the tower!
Nuts - pretty cloudy this morning. Not a good view of the liftoff from Central Florida.
}
Comments