Importance

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Abstract

A superframe lock subsystem includes a correlator which searches for and identifies a first unique word indicative of a frame boundary within a received bit stream during an initial acquisition state. A controller subsequently predicts frame boundaries in accordance with the first unique word. In a tentative frame lock state, the correlator searches for and determines if a second unique word exists at the frame boundary subsequent the frame boundary which corresponds to the first unique word. If the second unique word is determined to exist at the corresponding frame boundary and if a single frame duration separates the first and second unique words, the superframe lock subsystem enters a frame lock state. During the frame lock state, information of the corresponding frames is processed. The correlator searches for and determines if a carrier wave sequence indicative of a superframe boundary exists in the received bit stream at the frame boundary immediately following the frame boundary which corresponds to the second unique word. If the carrier wave sequence exists at the predicted frame boundary, the correlator searches for and determines if a third unique words exists in the received bit stream immediately after the carrier wave sequence. Upon determination that the third unique word exists subsequent the carrier wave sequence, the superframe lock subsystem enters a superframe lock state wherein the correlator searches for and detects only unique words at subsequent predicted frame boundaries to maintain superframe lock.

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First Claim