Gary P Fletcher

US Patent:

52300153, Jul 20, 1993

Filed:

Apr 19, 1991

Appl. No.:

7/688158

Inventors:

Shinya Yokodate - Kamakura, JP
Koji Kaneko - Kamakura, JP
Kazuyuki Saigusa - Kamakura, JP
Tatsuhiko Mizushima - Kamakura, JP
Scott A. Lewis - Davis CA
Gary S. Fletcher - Rocklin CA

Assignee:

Mitsubishi Denki Kabushiki Kaisha - Tokyo
Mitsubishi Electronics America, Inc. - Cypress CA

International Classification:

H04M 1100
H04N 712

US Classification:

379 53

Abstract:

A static video telephone for sending an image captured by an image capture-system and receiving a video signal transmitted over a telephone line. A video signal formed for transmission has a frame format including a phase shift correction data signal in addition to a frame synchronization signal, an amplitude calibration signal, an ID (information data) signal, and image data signal. The video telephone includes a frequency shift correction data generating circuit which is activated when frequency shifts are detected in the received signal and produces frequency-shift correction data. The frequency-shift correction data is then delivered to a subsequent demodulation timing generating circuit which scales phase errors in the received signal to produce phase error correction data. Both frequency-shift correction data and phase error correction data are combined together to produce a demodulation timing signal. With this signal, the received signal is demodulated.

US Patent:

49187180, Apr 17, 1990

Filed:

Jun 28, 1988

Appl. No.:

7/212549

Inventors:

Lawrence D. Emmons - Grass Valley CA
Gary Fletcher - Grass Valley CA

Assignee:

Luma Telecom, Inc. - Sunnyvale CA

International Classification:

H04M 1100
H04L 2720
H04L 2722

US Classification:

379 53

Abstract:

The present invention assigns amplitudes of sine wave cycles in a data packet on I and Q channels of a QAM signal to color, gray or luminance values. Overlapping sine wave cycles on the I and Q channels in the data packet are assigned to the same or neighboring pixels. A synchronizing signal is sent at the beginning of each transmission of a packet. The synchronizing signal is a plurality of cycles at a maximum amplitude on the I and Q channels. The synchronizing signal serves two functions simultaneously. First, it is used to indicate the beginning of a new packet. Second, the phase of the synchronizing signal is used to initialize the demodulator phase detecting circuitry.