Tamper-resistant, expandable communications system
First Claim
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1. In combination in a broadbandwidth multichannel cable network including a plurality of subscriber drops or terminal devices and a headend:
- a plurality of remote interrogator units connected in a branch of said network for receiving and storing subscriber drop channel allocation information from said headend and for selectively passing communications information to said headend anda plurality of groups of expansion modules connected in said branch of said network;
each module of said groups controlling a respective plurality of said subscriber drops or terminal devices;
all of said expansion modules of one of said groups having means for being selectively sequentially accessed by one of said remote interrogator units;
band stop filter means associated with each of said remote interrogator units and interposed in said branch of said network to isolate a group of said expansion modules in a segment of said branch for control by only one of said plurality of remote interrogator units, whereby control of others of said groups of expansion modules in other segments of said branch may be simultaneously maintained by others of said plurality of remote interrogator units in said branch.
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Abstract
An expandable, multipurpose digital and analog communications system in which a plurality of remote interrogator units connected in a branch of the system are isolated from one another by band stop filters to permit simultaneous polling without interference with other operations. Also disclosed is a premium service control unit which makes uses of a frequency agile oscillator.
221 Citations
6 Claims
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1. In combination in a broadbandwidth multichannel cable network including a plurality of subscriber drops or terminal devices and a headend:
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a plurality of remote interrogator units connected in a branch of said network for receiving and storing subscriber drop channel allocation information from said headend and for selectively passing communications information to said headend and a plurality of groups of expansion modules connected in said branch of said network;
each module of said groups controlling a respective plurality of said subscriber drops or terminal devices;
all of said expansion modules of one of said groups having means for being selectively sequentially accessed by one of said remote interrogator units;band stop filter means associated with each of said remote interrogator units and interposed in said branch of said network to isolate a group of said expansion modules in a segment of said branch for control by only one of said plurality of remote interrogator units, whereby control of others of said groups of expansion modules in other segments of said branch may be simultaneously maintained by others of said plurality of remote interrogator units in said branch. - View Dependent Claims (2, 3, 4, 5)
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6. A premium TV control unit for use in a cable network having a plurality of subscriber drops (220), comprising,
(a) a memory (707) for storing channel allocation and service feature information pertaining to a group of said subscriber drops (b) a jamming injection switch (704) for each of said drops, (c) a frequency-agile channel jamming means including a single digital frequency synthesizer (701); - voltage controlled oscillator means (702);
voltage variable attenuator means (712, 708, 709,
713) and(d) control means (706) for controlling each said jamming injection switch (704) in synchronism with said jamming means to apply a plurality of selectively variable time, frequency and amplitude bursts of channel-jamming signals directed to jam a distinctive plurality of channels individually delivered to said plurality of subscriber drops in accordance with said service feature information.
- voltage controlled oscillator means (702);
Specification