Digital signal processing

• Main Authors: THIRLWALL, ALAN CLIVE, IVE, JOHN GOODWIN SPENCER
• Format: Patent
• Language: English; French; German
• Published: 26.05.1982
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; PHYSICS; PICTORIAL COMMUNICATION, e.g. TELEVISION; TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHICCOMMUNICATION

Apparatus for extracting synchronizing information from an incoming serial-bit digital television signal formed of a sequence of word blocks, each word block being formed of N n-bit words and each word block including a predetermined serial group of m bits forming said synchronizing information, and for de-serializing the incoming digital signal in dependence on the synchronizing information, comprises an m-stage shift register (2) through which the incoming digital signal is stepped at the bit rate of the incoming digital signal, the first shift register (2) supplying a pulse when it holds the predetermined serial group of m bits, a frequency divider (9) to derive from the incoming digital signal a word rate clock pulse signal, an n-stage shift register (4) through which each said pulse is stepped at the bit rate of the incoming digital signal, a latch circuit (10) synchronized with the word rate clock pulse signal to derive n-bit phase words the bits of which correspond respectively to the conditions of the n stages of the shift register (4), comparators (16 to 19) comparing each phase word with at least one other phase word derived N or an integral multiple of N word periods of the incoming digital signal earlier, the comparators (16 to 19) supplying a control signal only when at least one of the comparisons indicates two phase words which are identical and both contain a bit corresponding to a said pulse, the position of this bit in the phase words indicating the phasing of the word rate clock pulse signal relative to the words of the incoming digital signal, and circuits (5,6,7,24) to de-serialize the incoming digital signal into parallel-bit n-bit words under control of the control signal.