The apparatus and method are employed in a communications system has a transmitter and a receiver, where the receiver determines at which of several rates individual frames in a signal have been transmitted by the transmitter. For example, if the transmitter employs four transmission rates,...http://www.google.com.au/patents/US5751725?utm_source=gb-gplus-sharePatent US5751725 - Method and apparatus for determining the rate of received data in a variable rate communication system 
