Title:
OSCILLATION CIRCUIT SCHEME, MODULATION SCHEME, DEMODULATION SCHEME, AND MULTILEVEL QAM MODULATION/DEMODULATION SYSTEM
Document Type and Number:
WIPO Patent Application WO/1999/041838
Kind Code:
A1
Abstract:
A local oscillation circuit for loop frequency conversion used to realize an AV transmission system adopting 64 QAM modulation/demodulation scheme for, e.g., a digital cable system in a mobile body involving vibration, such as an aircraft. Conventionally phase variation is caused by microphonic noise attributed to vibration, and hence the bit error rate in modulation/demodulation and transmission increases because of the phase vibration. To reduce the phase variation, (a) the phase comparison frequency being set in a PLL synthesizer used as a local oscillation circuit for frequency conversion is raised, (b) the values of components of a loop filter section of the PLL synthesizer are determined so that the natural angular frequency ($g(v)n) of the loop filter section may be above the frequency range of the vibration, and (c) the loop filter section is provided with a plastic film capacitor hardly producing shock noise.
Inventors:
TANAKA SHOTARO (JP)
Application Number:
PCT/JP1999/000604
Publication Date:
August 19, 1999
Filing Date:
February 10, 1999
Export Citation:
Assignee:
MATSUSHITA ELECTRIC IND CO LTD (JP)
TANAKA SHOTARO (JP)
TANAKA SHOTARO (JP)
International Classes:
H03L7/093; H03L7/18; H03L7/183; H04L27/34; H04N7/24; H04N21/2383; H04N21/438; (IPC1-7): H03L7/18; H04L27/34
Foreign References:
| JPS56119533A | 1981-09-19 | |||
| JPH08265147A | 1996-10-11 | |||
| JPH0529933A | 1993-02-05 | |||
| JPH07288483A | 1995-10-31 | |||
| JPS62125030U | 1987-08-08 | |||
| JPH03174816A | 1991-07-30 | |||
| JPH04142813A | 1992-05-15 | |||
| JPS62172819A | 1987-07-29 | |||
| JPS64845A | 1989-01-05 | |||
| JPH09307481A | 1997-11-28 | |||
| JPH0823290A | 1996-01-23 |
Attorney, Agent or Firm:
Higashima, Takaharu (Umeda 3-chome Kita-ku, Osaka-shi Osaka, JP)
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