A system for determining angular rate of rotation of a body about a rate axis. In one arrangement, the system comprises first (10) and second (12) accelerometers, movement apparatus and processor. The first and second accelerometers have their sensitive axes (16, 18) parallel to a sensing axis that is...http://www.google.se/patents/US4712426?utm_source=gb-gplus-sharePatent US4712426 - Synchronous FM digital detector
