Settop terminal controlled return path filter for minimizing noise ingress on bidirectional cable systems
First Claim
1. A device for selectively passing RF energy in a CATV communication path from a settop terminal to a headend, comprising:
- monitoring means for monitoring a selected bandwidth within the communication path;
detecting means having a unique address, responsive to said monitoring means, for detecting a valid communication signal transmitted from the settop terminal within at least a portion of said bandwidth, wherein said valid communication signal includes the unique address of said detecting means; and
controllable filter means, responsive to said detecting means, for passing RF energy in said bandwidth portion when a valid communication signal has been detected and blocking all RF energy within said bandwidth portion with a shunt filter when a valid communication signal has not been detected.
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Accused Products
Abstract
A device which eliminates all RF ingress noise from entering the CATV network in the upstream communication path includes a shunt filter, a detector and a filter with a bandwidth equal to the bandwidth of the upstream communication path. The device monitors signals transmitted in the upstream bandwidth and detects when a valid upstream communication is being transmitted. Upon detection of this valid signal, the shunt filter is switched out of the upstream communication path to allow the valid transmission to be sent. When the end of the valid transmission is detected and a predetermined delay has lapsed, the shunt filter is switched to block all upstream transmissions in the upstream communication bandwidth.
133 Citations
13 Claims
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1. A device for selectively passing RF energy in a CATV communication path from a settop terminal to a headend, comprising:
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monitoring means for monitoring a selected bandwidth within the communication path; detecting means having a unique address, responsive to said monitoring means, for detecting a valid communication signal transmitted from the settop terminal within at least a portion of said bandwidth, wherein said valid communication signal includes the unique address of said detecting means; and controllable filter means, responsive to said detecting means, for passing RF energy in said bandwidth portion when a valid communication signal has been detected and blocking all RF energy within said bandwidth portion with a shunt filter when a valid communication signal has not been detected. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A device for selectively passing RF energy over a CATV communication path from a settop terminal to a headend having a plurality of subbands comprising:
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a plurality of monitoring means, each having a unique address and each for monitoring a different selected subband within the communication path; a plurality of detecting means, each responsive to one of said monitoring means, for detecting a valid communication signal transmitted from a settop terminal within the selected subband, wherein said valid communication signal includes the unique address of at least one of said monitoring means; and a plurality of controllable filter means, each responsive to one of said detecting means, for passing RF energy over the selected subband when a valid communication signal has been detected within the selected subband and blocking all RF energy within said bandwidth portion with a shunt filter when a valid communication signal has not been detected within the selected subband.
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11. A device for selectively passing RF energy in a CATV communication path from a settop terminal to a headend responsive to a transmitted DC signal, transmitted within said path, which indicates when to pass the RF energy comprising:
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detecting means for detecting the transmitted DC signal from the settop terminal; and filter means, responsive to said detecting means, for selectively passing RF energy as indicated by the DC signal. - View Dependent Claims (12, 13)
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Specification