The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 03, 2002
Filed:
May. 14, 1999
Kazuhiko Shibuya, Setagaya-ku, Tokyo 157-8510, JP;
Junji Kumada, Setagaya-ku, Tokyo 157-8510, JP;
Yuichi Iwadate, Setagaya-ku, Tokyo 157-8510, JP;
Hiroyuki Hamazumi, Setagaya-ku, Tokyo 157-8510, JP;
Toshihiro Nomoto, Setagaya-ku, Tokyo 157-8510, JP;
Kouichi Takano, Setagaya-ku, Tokyo 157-8510, JP;
Tomohiro Saito, Setagaya-ku, Tokyo 157-8510, JP;
Shoji Tanaka, Setagaya-ku, Tokyo 157-8510, JP;
Fumiaki Minematsu, Setagaya-ku, Tokyo 157-8510, JP;
Akinori Hashimoto, Setagaya-ku, Tokyo 157-8510, JP;
Shigeyuki Itoh, Setagaya-ku, Tokyo 157-8510, JP;
Hajime Matsumura, Setagaya-ku, Tokyo 157-8510, JP;
Hisakazu Katoh, Sibuya-ku, Tokyo 150-8001, JP;
Masaru Takechi, Setagaya-ku, Tokyo 157-8510, JP;
Other;
Abstract
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.