Title:
VIDEO SIGNAL MONITOR SYSTEM IN CATV TRANSMISSION SYSTEM
Document Type and Number:
Japanese Patent JP3233439
Kind Code:
B2
Abstract:
PURPOSE: To facilitate grasp of a fault by allowing a center to monitor a video signal at an optional position of a transmission line.
CONSTITUTION: A center equipment A designates a channel (ch) and a position by a channel designation means X1 and a position designation means X2, modulates ch identification data (chD) and address data(AD) and sends the result to a control channel by a control data transmission means X3, receives a monitor channel video signal and an audio band signal and displays respectively the video image and its state by a video state display means X4 and a state display means X5. Each of return devices B1-Bn uses a demodulation means Y1 to demodulate a chD and an AD from the control channel, uses a selection means Y3 to separately extract a video signal and an audio signal of a channel relevant to the chD, uses a state detection means Y4 to detect state data of a transmission line, uses a data modulation means Y5 to modulate the state data into a signal of an audio signal band, uses a selection means Y6 to select either the modulation signal of the state data or the audio signal and frequency-converts the audio band signal as the audio signal in a television signal together with the extracted video signal into a frequency of an incoming monitor channel and sends the result to a transmission line by a monitor video/state transmission means Y7, when the designation of its own device is discriminated by an address discrimination means Y2.
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Inventors:
Katsuyuki Koike
Application Number:
JP8993092A
Publication Date:
November 26, 2001
Filing Date:
March 14, 1992
Export Citation:
Assignee:
Aichi Electronics Co., Ltd.
International Classes:
H04N7/173; H04N17/00; H04N21/61; H04N21/647; (IPC1-7): H04N7/173; H04N17/00
Domestic Patent References:
| JP6318889A | ||||
| JP3162082A | ||||
| JP3256486A | ||||
| JP3108988A | ||||
| JP346487A | ||||
| JP214693A | ||||
| JP583708A | ||||
| JP4304797A | ||||
| JP4227196A | ||||
| JP6156588A | ||||
| JP5915386A |
Attorney, Agent or Firm:
Osamu Fujitani