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By Design News Staff -- Design News, July 7, 1997
Sensor improves ABS
Under development for 1999-model year automobiles, a new ABS system offers to improve low-speed (below 3-4 mph) traction-control-system performance. The secret: wheel speed-sensors that leverage the latest giant magnetoresistive (GMR) technology and can maintain large signal outputs at low frequencies.
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| Manufactured from alternating, ultra-thin layers of ferromagnetic and non-magnetic materials, GMR devices are so-named because the magnetoresistance effect is large compared to conventional solid state magnetic sensors. |
The sensor works in conjunction with a toothed sprocket incorporated into the wheel bearings. As the sprocket rotates, its teeth perturb the magnetic field and create a dynamic signal in the sensitive axis of the sensor.
GMR devices measure magnetic field strength directly and will produce an output even if the field is static. This provides for operation right down to DC. Other applications? Transmissions, camshafts, industrial gear-tooth sensing. Nonvolatile Electronics, Inc., 11409 Valley View Road, Eden Prairie, MN 55344-3617, 800-467-7141.
Smart bag tags
Imagine matching every bag in an aircraft's cargo hold to a passenger without sorting or unpacking. That's what a low cost, passive, read/write radio frequency identification (RF/ID) system offers airline security teams trying to comply with the Gore Commission's Federal PPBM Mandate.
| On-chip power conversion when passed through an RF field eliminates the need for cumbersome batteries and allows the chip to remain active indefinitely. |
The system, comprised of scanner and microchip-embedded labels, has a 1.5- to 6-ft scanning range. Based on field-programmable gate-array technology, the system's two-way protocol between chip and scanner facilitates reading 50 labels/sec and writing as much as 1024 bits to permanent memory. Data is tamper-proof, resisting static, UV light, extreme voltage and operating temperatures.
Standard 0.8 µ CMOS silicon manufacturing yields a 2.54-GHz chip for $0.95 each. Pallet and parcel tracking, textile rental and cleaning, pharmaceuticals and brand name verification are some other applications.
Rick Ono, SCS Corp., 10905 Technology Place, San Diego, CA 92127, Fax: (619) 485-0561 or info@scs-corp.com
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