Super Precise GPS

MEMSIC, a semiconductor company located in Andover, Massachusetts, has developed the new MMC212xM, a magnetic sensor that will enable greatly improved location-based services (LBS) in cellular phones and handheld GPS systems. The new component will enable greater precision and automated calibration in traceable handheld devices. These improvements should enable a greater suite of localized services such as information about nearby restaurants or stores, constantly updated directions, efficient scheduling of taxi cabs, or warnings of nearby traffic jams.
A functional block diagram of the MMC212xM sensor (Credit: MEMSIC )
A functional block diagram of the
MMC212xM sensor (Credit: MEMSIC)

The MMC212xM sensor is the first of several planned new magnetic sensors designed for LBS applications. The sensor operates on minimal power, requiring only 0.4 mA at 3V with 50 location measurements per second, making it ideal for handheld devices operating on battery power. The sensor also takes advantage of the MEMSIC Intelligent Heading Correction algorithms, which compensate for magnetic interference and provide automatic calibration.

The full package is small, only 5 mm x 5 mm x 0.9 mm and includes both onboard signal processing capabilities and an integrated I2C bus. It can be connected directly to a microprocessor, eliminating the need for separate timing devices and other external control components. It uses ten pins, two of which are reserved for factory use. The other eight connect to the power supply, external capacitors, and ground as well as the clock, and data lines for the IC2 bus.
The MMC212xM is actually a set of anisotropic magnetoresistive (AMR) sensors made of two series of four nickel-iron thin film resistors deposited on a silicon wafer in a Wheatstone bridge formation. Each bridge formation enables the sensor to measure both the field magnitude and direction along a single axis. Together, the two series of sensors provide data for both the x and y axes that can then be used to determine location very accurately.
In addition to location based services, this new magnetic sensor can be used in electronic compasses and vehicle detection. Volume production of the sensor is ramping up now at an initial cost of $3.85 per sensor with the purchase of 1,000 units. Evaluation boards are also available from MEMSIC.
TFOT has reported on other innovations improving the capabilities of handheld devices including the world’s smallest handheld GPS device, a handheld medical scanner similar to Star Trek’s tricorders, a cellular phone with an onboard microscope capable of up to 50x magnification, and turbine engines with a diameter of a millimeter that should decrease battery size considerably.
You can read the MEMSIC press release about the MMC212xM here. You can also find extensive technical information about the MMC212xM in the product datasheet found here (PDF). An extensive discussion of AMR sensors and their capabilities can be found here.

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