Title:
DIGITAL FM DEMODULATOR
Document Type and Number:
Japanese Patent JP3231636
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To prevent inversion of a luminance signal from a white level into a block level due to distortion after magnetic recording and reproduction of an FM modulated luminance signal in a VTR or the like.
SOLUTION: An FM modulated luminance signal (a) is amplified by a head amplifier 1 and given to an A/D converter 2, in which the signal is sampled and converted into digital data (b). A Hilbert converter 3 converts the digital data (b) into complex data having a phase difference of 0° and 90°. A circumcenter generator 4 obtains the coordinates of a circumcenter based on three consecutive points of the complex data, a coordinate converter 5 receives the coordinate of the circumcenter and obtains new complex data whose origin is shifted by the coordinates of the circumcenter and provides an output of the result. A demodulator 6 obtains the phase angle of the FM modulated luminance signal from the new complex data through arc tangent arithmetic operation and differentiates the phase angle to apply FM demodulation to the signal.
Inventors:
Hiroshi Omura
Kuniaki Fujii
Kuniaki Fujii
Application Number:
JP28258896A
Publication Date:
November 26, 2001
Filing Date:
October 24, 1996
Export Citation:
Assignee:
Sharp Corporation
International Classes:
H04N5/922; G11B20/06; H03D3/00; (IPC1-7): H04N5/922; G11B20/06; H03D3/00
Domestic Patent References:
| JP62285592A | ||||
| JP647730A |
Attorney, Agent or Firm:
Eisuke Fujimoto