Synchronous signal detecting circuit, method, and information storage medium

Abstract

When a sync pattern in a frame of a bit stream is detected to synchronize a data processing apparatus with the bit stream, data patterns containing a pattern identical to the sync pattern are often erroneously detected as the sync pattern. In order to overcome such problem, an apparatus for detecting data in a bit stream is provided. The bit stream contains a sequence of frames, and each frame has a predetermined number of bits and comprises a sync pattern and a data portion. The apparatus contains a detecting circuit, a counting circuit, and a synchronization signal generating circuit. The detecting circuit detects a first data pattern in the bit stream that equals the sync pattern and detects a second data pattern in the bit stream that equals the sync pattern. The counting circuit begins counting bits in the bit stream to generate a count value when the first data pattern is detected by the detection circuit. The synchronization signal generating circuit receives the count value from the counting circuit and compares the count value with a predetermined value when the second data pattern is detected by the detecting circuit. Then, the generating circuit outputs a synchronization signal when the count value and the predetermined value have a predetermined relationship.