Abstract: Apparatus and methods are disclosed for recovering alignment from a non-ideally encoded multi-bit digital signal without the need to embed framing information within the encoded signal or append framing bits thereto. In particular, the invention is disclosed in the context of recovering septet alignment in a sub-band ADPCM (adaptive differential pulse code modulated) 7 kHz audio digital signal without the need to embed any framing information within the digital signal itself. Specifically, in this context, this method relies on first gathering statistics from a 56 kbit/second 7 kHz audio digital signal itself for a pre-defined number of incoming bits that occur during a measurement interval and for every one of seven possible alignments for a septet.

Abstract: Apparatus and method for analyzing a bit stream to determine whether the stream is encoded in A-law PCM or .mu.-law PCM. Bit positions 2, 3, and 4 are examined to determine which of the 8 possible segment codes are present. Segment codes representing low amplitude speech should predominate statistically over segment codes representing high amplitude speech. If the sample cannot be classified by the appearance of low amplitude segments, the higher amplitude segments are compared and that coding law is detected as being present which accrues the lower count for such high amplitude segments.