Passive-active terminal adapter and method having automatic return loss control
First Claim
1. A passive-active terminal adapter for use in connecting subscriber devices to receive downstream signals from a cable television network and to deliver upstream signals from the subscriber devices to the network, in which electrical power is supplied to operate the terminal adapter, comprising:
- a signal splitter which separates downstream signals into active branch downstream signals and passive branch downstream signals;
a passive branch circuit receptive of the passive branch downstream signals;
an active branch circuit receptive of the active branch downstream signals, the active branch circuit including an active signal conditioner which modifies characteristics of the active branch downstream signals conducted through the active branch circuit;
a sensor configured to detect changes in voltage in the electrical power, detect changes in current consumed by the terminal adaptor, or both, in the active branch circuit, wherein the changes are indicative of a normal operative condition and an unanticipated impedance state, the sensor supplying a first control signal indicative of the normal operating condition and supplying a second control signal indicative of the unanticipated impedance state; and
a switch receptive of the first and second control signals and connected to the signal splitter and the active branch circuit and a termination impedance, the switch having a first operative position which conducts the active branch downstream signals from the splitter to the active branch circuit, the switch also having a second operative position which conducts the active branch downstream signals from the splitter to the termination impedance and which disconnects the active branch circuit from the splitter, the switch assuming the first operative position in response to the first control signal and assuming the second operative position in response to the second control signal.
4 Assignments
0 Petitions
Accused Products
Abstract
Return loss due to excessive signal reflection into a cable television (CATV) network from an inoperative or abnormally operative terminal adapter is minimized, to communicate enhanced passive downstream signals to passive subscriber devices such as “life-line” telephone sets. A predetermined termination impedance is substituted for an active branch circuit of the terminal adapter whenever reduced input voltage, over-current or under-current conditions exist in the terminal adapter.
193 Citations
20 Claims
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1. A passive-active terminal adapter for use in connecting subscriber devices to receive downstream signals from a cable television network and to deliver upstream signals from the subscriber devices to the network, in which electrical power is supplied to operate the terminal adapter, comprising:
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a signal splitter which separates downstream signals into active branch downstream signals and passive branch downstream signals; a passive branch circuit receptive of the passive branch downstream signals; an active branch circuit receptive of the active branch downstream signals, the active branch circuit including an active signal conditioner which modifies characteristics of the active branch downstream signals conducted through the active branch circuit; a sensor configured to detect changes in voltage in the electrical power, detect changes in current consumed by the terminal adaptor, or both, in the active branch circuit, wherein the changes are indicative of a normal operative condition and an unanticipated impedance state, the sensor supplying a first control signal indicative of the normal operating condition and supplying a second control signal indicative of the unanticipated impedance state; and a switch receptive of the first and second control signals and connected to the signal splitter and the active branch circuit and a termination impedance, the switch having a first operative position which conducts the active branch downstream signals from the splitter to the active branch circuit, the switch also having a second operative position which conducts the active branch downstream signals from the splitter to the termination impedance and which disconnects the active branch circuit from the splitter, the switch assuming the first operative position in response to the first control signal and assuming the second operative position in response to the second control signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of minimizing return loss in downstream signals conducted through a passive branch circuit of a passive-active terminal adapter which also includes an active branch circuit which conducts downstream signals, comprising:
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connecting the active and passive branch circuits of the terminal adapter to receive downstream signals from a cable television network; supplying electrical power to the terminal adapter; sensing changes in voltage in the electrical power, changes in current consumed by the terminal adapter, or both; recognizing a normal operating condition and an unanticipated impedance state based on the sensing; providing a control signal that is indicative of normal operation condition to the passive-active terminal adapter in response to the normal operation condition that was recognized; and substituting a termination impedance having a predetermined impedance characteristic for the active branch circuit in response to the unanticipated impedance sate that was recognized. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification