Bi-directional CATV system, line equipment, center equipment
First Claim
1. A bi-directional CATV system, in which a plurality of line equipment are connected to transmission lines from a center equipment to subscriber terminal devices, comprising means for specifying the line equipment located the closest upstream of a noise source when a noise level received by the center equipment exceeds a predetermined maximum noise level, and means for increasing attenuation of upward signal at the line equipment.
1 Assignment
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Accused Products
Abstract
When a noise level of upward signal received by a center equipment exceeds a predetermined maximum noise level, line equipment located the closest upstream from a noise source is specified and attenuation of the upward signal on the specified line equipment is increased in levels until the noise level of the upward signal received by the center equipment is equal to or under the maximum noise level. Accordingly, it is possible to prevent abnormal noise to affect the whole system without interrupting the upward signal from a cable modem located downstream of the noise source to the center equipment.
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Citations
7 Claims
- 1. A bi-directional CATV system, in which a plurality of line equipment are connected to transmission lines from a center equipment to subscriber terminal devices, comprising means for specifying the line equipment located the closest upstream of a noise source when a noise level received by the center equipment exceeds a predetermined maximum noise level, and means for increasing attenuation of upward signal at the line equipment.
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3. Line equipment connected to transmission lines of a bi-directional CATV system from a center equipment to subscriber side terminal devices, comprising
transmission line means for transmitting downward signal from the center equipment and signal attenuation means for varying attenuation of upward signal to the center equipment according to attenuation adjustment signal superimposed on the downward signal transmitted from the transmission line means.
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6. A center equipment of a bi-directional CATV system in which a plurality of line equipment are connected to transmission lines to subscriber side terminal devices comprising:
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noise level detection means for detecting a noise level in a frequency band used for transmission of upward signal;
search means for searching a noise source to specify the line equipment located the closest upstream of the noise source when the noise level detected by the noise level detection means exceeds a predetermined maximum noise level; and
noise adjustment means for generating attenuation adjustment signal to adjust attenuation of the upward signal at the line equipment specified by the search means so that the noise level detected by the detection means is equal to or under the maximum noise level and mixing the attenuation adjustment signal on downward signal to be transmitted. - View Dependent Claims (7)
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Specification