Line monitoring device in two-way data communication system
First Claim
1. A line monitoring device for use in a two-way data communications system for carrying out data communications between a central facility and a plurality of terminal units comprising:
- an address detection section for comparing a digital address included in a polling down-signal from said central facility with a pre-stored digital address;
a response signal detecting section for detecting up-signals from said terminal units; and
a display section operating in response to said address detection section and said response signal detecting section to display the level of an up-signal from a terminal unit whose address coincides with said pre-stored address.
1 Assignment
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Accused Products
Abstract
A line monitoring device for use in a two-way data communication system such as a CATV system in which up-signals are transmitted by terminal units in response to retrieving signals applied thereto from a central facility to monitor the levels produced by the various terminal units. An address detection signal compares the address number included in a polling down-signal from the central facility with an address prestored in the monitoring device. A response signal detection section detects the up-signals from the terminal units. A display section operates in response to the address detection section to display the level of an up-signal from a terminal unit as produced on the output of the response signal detection section when the address received from the central facility coincides with the pre-stored address.
128 Citations
7 Claims
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1. A line monitoring device for use in a two-way data communications system for carrying out data communications between a central facility and a plurality of terminal units comprising:
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an address detection section for comparing a digital address included in a polling down-signal from said central facility with a pre-stored digital address; a response signal detecting section for detecting up-signals from said terminal units; and a display section operating in response to said address detection section and said response signal detecting section to display the level of an up-signal from a terminal unit whose address coincides with said pre-stored address. - View Dependent Claims (2, 3, 4, 5)
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6. A line monitoring device for use in a two-way data communication system for carrying out data communications between a central facility and a plurality of terminal units comprising:
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a low-pass filter having an input coupled to an input terminal, said input terminal being adapted to be connected to a branch cable of said data communication system; a variable attenuator having an input coupled to an output of said low-pass filter; amplifier and detector means having an input coupled to an output of said attenuator; a peak detector circuit having an input coupled to an output of said amplifier and detector means; an analog-to-digital converter having a signal input coupled to an output of said peak detector; digital display means operating in response to digital outputs of said analog-to-digital converter; a high-pass filter having an input coupled to said input terminal; a digital demodulator having an input coupled to an output of said high-pass filter; digital switch means for setting in a selected address; and comparison means for comparing a digital address set in by said digital switch means with digital address data outputted by said receiver means, a comparison output of said comparison means being coupled to operate said peak detector and said analog-to-digital converter. - View Dependent Claims (7)
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Specification