it senses speed.
Quoteit senses speed.No, it senses magnetic fields.You need a shaft encoder. I don't know of any solid-state ones, so a Gray code encoder is probably the only sensible absolute position sensor.
You have not said what kind of resolution you need. Austria Microsystems makes the Hall Effect absolute encoders in 8, 10, 12, an d 14 bit resolution (256, 1024, 4096, 16384 steps): http://www.ams.com/eng/Products/Magnetic-Encoders/Rotary-EncodersDigiKey has the AS5263 (12-bit) for $10.22 each: http://www.digikey.com/product-detail/en/AS5263-HQFT/AS5263-HQFTCT-ND/3028680