Honeywell rotary SMART sensor designed to replace encoders, resolvers.
Honeywell introduced a rotary configuration to its SMART position sensor line that provides 360 degree non-contact angular position sensing. The component uses a combination of an ASIC and an array of magneto-resistive sensors to determine the position of a magnet collar, down to 0.01 degrees. Repeatable output that occurs within a 3.0 mm ±2.0 mm [0.118 in ±0.079 in] air gap between the sensor and magnet collar expand application opportunities. The sensor also provides minimal signal error with up to 2.50 mm [0.10 in] of radial error.
http://sensing.honeywell.com