Other

Masaru Takechi

Shigeyuki Itoh

Tomohiro Saito

Shoji Tanaka

Akinori Hashimoto

Hisakazu Katoh

Toshihiro Nomoto

Hajime Matsumura

Junji Kumada

Kazuhiko Shibuya

Fumiaki Minematsu

Yuichi Iwadate

Kouichi Takano

Hiroyuki Hamazumi

Stabilized carrier recovery is achieved even at the time of a low C/N ratio by measuring the phase of a signal and controlling VCO or NCO (Numerical Controlled Oscillator) using only a period having few constellation points. At this time, false lock phenomenon is avoided as follows. That is, relatively short SYNC modulated by an already-known pattern is entered into a modulation wave, VCO or NCO oscillation frequency is swept in a wide range and sweep is stopped at a frequency in which the SYNC can be received, thereby carrying out coarse control AFC. Further, a period having long to some extent, having few constellation points is provided in the modulation wave and then, a difference between the frequency of a received modulated signal and a local oscillation signal of VCO or NCO is obtained in this period. This frequency difference is analyzed according to the phase differential function method, self-correlation function method or count method, and the VCO or NCO is controlled based on this result of analysis.

AFC circuit, carrier recovery circuit and receiver device capable of regenerating a carrier reliably even at the time of low C/N ratio

Growing community of inventors

Setagaya-ku, Tokyo, Japan

Masaru Takechi