CARRIER SYNCHRONOUS DEMODULATOR

• Main Authors: NAKAMURA YASUHISA, SAITO YOICHI, TAKANASHI HITOSHI, AIKAWA SATOSHI
• Format: Patent
• Language: English
• Published: 30.07.1990
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHICCOMMUNICATION

PURPOSE:To synchronize an output phase with a correct detection phase in a short time with simple circuit constitution by discriminating the presence of many errors in an output of a means identifying the error, and transforming the phase of a demodulation circuit. CONSTITUTION:A multi-value code subject to multi-value phase modulation and having a redundant code for error detection or correction with a prescribed logic is inputted to an input terminal 1 as a reception signal. A carrier recovery circuit 2 is a circuit having phase uncertainly. An output of a demodulation circuit 4 is inputted to a Viterbi decoding circuit 12 via a selector 11 and the Viterbi decoding circuit 12 applies error correction according to a prescribed logic and the decoded signal is sent to a decoding signal output terminal 14. Then a discrimination circuit 13 receiving the result of error identification by the Viterbi decoding circuit 12 and discriminating the presence of many errors in the result of identification is provided, the demodulation output signal from the demodulation circuit 4 is transformed according to the output of the discrimination circuit 13 and gives the phase of the demodulation carrier to a selector 11 applying transformation substantially as a control signal. Thus, the correct detection phase is synchronized in a short time with simple circuit constitution.