Method and apparatus for data recovery

Abstract

A method and apparatus for recovering data by a digital audio interface, where the data may be transmitted over a single transmission path in accordance with the AES3-1992 standard, begins by receiving a stream of biphase encoded data. The biphase encoded data is organized as a series of data block that each include a plurality of frames. The processing continues by determining whether a next transition of a frame of the plurality of frames occurs during a first, second, or third time window after a preceding transition of the frame. When the next transition occurs during the second predetermined time, the digital audio interface synchronizes to a data rate of the stream of biphase encoded data based on the next transition and the preceding transition. In other words, the transitions of the data within the frame are occurring at the data rate. (Note that biphase encoding encodes a logic zero as no transition during a clock interval, encodes a logic one as a transition during a clock interval, and provides a transition at the next clock interval to indicate a new bit). If, the next transition occurs during the first or third predetermined windows, the digital audio interface synchronizes to a data rate of the stream of biphase encoded data based on the preceding transition edge and a subsequent transition. For example, when the next transition occurs during the first time window, the transition is representative of a logic one, where the subsequent transition corresponds to the beginning of the next bit. When the transition occurs during the third time window, the biphase encoding is violated, which indicates that a preamble is being received.