Recovering synchronization in a data stream

Data synchronization apparatus comprising:

• means for applying a reversible operation to a word in a sequence of data words in a data stream and for applying a first function to a pseudo-random (PN) state of a PN generator that corresponds to the word;
• means for appending a bit to the word prior to transmitting the word in a data stream where the appended bit corresponds to the state of the PN generator;
• means for discovering the location of the PN sequence in the data stream of received data and for determining the PN state corresponding to that PN sequence;
• means for aligning received word boundaries with respect to the location of the PN sequence;
• and
• means for applying the reverse of the reversible operation to each received word and for applying the first function to the PN state associated with the PN sequence bit which was appended to the word thus restoring the original data.

Synchronization recovery apparatus comprising:

• means for determining a bit location of a sync bit in a data stream where the sync bit is a bit from a pseudo-random (PN) generated sequence;
• means responsive to the sync bit in the determined bit location for detecting a PN state corresponding to the sync bit in the PN sequence,
• the bit location determining means and PN state detecting means comprising:
• an array of correlators, each correlator including:
• a PN state detector and
• counter and control means;
• means for selecting an output from a correlator;
• and
• flywheel means responsive to the detected PN state and to the counter and control means for operating the selected correlator so as to use or not to use the output of a PN generator and correlator position as the PN state and as the bit location of the sync bit, respectively.

A system for recovering synchronization of data symbols between a transmitter and a receiver, the system comprising:

• transmitter means for buffering error correcting code (ECC) codewords, each ECC codeword including at least one data symbol;
• transmitter means for converting buffered ECC codewords into a sync word data field;
• transmitter means for respectively appending a pseudo-randomly (PN) generated sync pattern to each of a plurality of sync word data fields;
• receiver means responsive to the transmitter PN generated sync pattern for recovering synchronization and for aligning a data symbol into its proper position in a received ECC codeword;
• means for receiving an ECC block of sync words, a sync word being formed by a transmitter appending a sync bit from the pseudo-randomly generated sync pattern to a sync word data field;
• means for detecting the pseudo-random pattern of sync bits in a plurality of the Sync words of the ECC block;
• and
• means responsive to the detected pseudo-random pattern for generating addresses in a read buffer into which the symbols from the plurality of sync words are to be written.

Synchronization recovery apparatus comprising:

• means for receiving a word of predetermined size, the received word including a first pseudo-randomly generated sync bit from a pseudo-random (PN) sequence;
• means for generating a second pseudo-randomly generated sync bit sequence, where the second pseudo-randomly generated sync bit sequence is a reconstruction of the first pseudo-randomly generated sync bit sequence;
• means for correlating a bit of a received word with a bit from the second, reconstructed pseudo-randomly generated bit sequence;
• and
• means responsive to the correlation for aligning the received word as an aligned sync word;
• means responsive to the alignment for identifying a sync bit in the aligned sync word;
• and
• means responsive to the sync bit in the aligned sync word for generating an address for writing the aligned sync word in a read buffer.

Synchronization recovery apparatus comprising:

• means for receiving a word of predetermined size, the received word including a first pseudo-randomly generated sync bit from a pseudo-random (PN) sequence;
• means for generating a second pseudo-randomly generated sync bit sequence, where the second pseudo-randomly generated sync bit sequence is a reconstruction of the first pseudo-randomly generated sync bit sequence;
• means for correlating a bit of a received word with a bit from the second, reconstructed pseudo-randomly generated bit sequence;
• and
• means responsive to the correlation for aligning the received word as an aligned sync word;
• means responsive to the reconstructed pseudo-randomly generated sync bit for determining a "most likely" bit position for a sync bit within the received word;
• and
• means responsive to the reconstructed pseudo-randomly generated sync bit and responsive to the "most likely" sync bit position for generating an address corresponding to the sync word within the error correcting code (ECC) block.

Synchronization recovery apparatus comprising;

• means for receiving a word of predetermined size, the received word including a first pseudo-randomly generated sync bit from a pseudo-random (PN) sequence;
• means for generating a second pseudo-randomly generated sync bit sequence, where the second pseudo-randomly generated sync bit sequence is a reconstruction of the first pseudo-randomly generated sync bit sequence;
• means for correlating a bit of a received word with a bit from the second, reconstructed pseudo-randomly generated bit sequence;
• and
• means responsive to the correlation for aligning the received word as an aligned sync word;
• and
• means for writing the aligned sync word in a read buffer.

Apparatus for associating a pseudo-random (PN) state of a first PN generator with data locations in a read buffer, the read buffer for storing data words, the apparatus comprising:

• means for discovering the position of a PN sequence in a data stream of data words and for determining the PN state corresponding to the PN sequence in the data stream;
• means responsive to an output from a PN detector and to the position of the PN sequence in the data stream for aligning word boundaries with respect to the location of the PN sequence;
• and
• means for associating the PN state of the PN sequence in the data stream with locations in the read buffer so that data can be written into locations in the read buffer corresponding to those locations the data occupied in a write buffer.

Apparatus for applying a reversible operation to each word of a sequence of data words in a data stream, the apparatus comprising:

• means responsive to each pseudo-random (PN) state of a PN generator for applying a first function to a data word;
• the first function including:
• means responsive to the PN state for generating a randomizing bit pattern;
• and
• means for applying the randomized bit pattern to the data word;
• means for appending a corresponding bit from a PN sequence that is provided by the PN generator, the bit being appended to the data word prior to communicating the data word in the data stream;
• means for discovering the location of the PN sequence in the data stream;
• means for determining the PN state corresponding to the discovered PN sequence.

A synchronization recovery method comprising the steps of:

• associating a pseudo-random (PN) state of a transmitter PN generator with a data location in a write buffer;
• appending a bit from a PN sequence from the transmitter PN generator to data read from the write buffer to generate a sync word;
• transmitting the sync words in a bit stream;
• locating the appended PN sequence bit position in received data words from the bit stream;
• recovering the PN state corresponding to the received sync word from the received PN sequence;
• responsive to the recovered PN state, associating the PN state of the received sync word with a data location in a read buffer;
• and
• responsive to the PN sequence bit position in the received sync word, aligning word boundaries of the received sync word with respect to the location of the appended position within the PN sequence.