Addressable network interface units suitable for use in FTTX and RFOG networks and related methods of controlling bandwidth allocation and identifying noise sources in such networks
View Patent ↗An addressable optical network interface unit includes an optical input and a radio frequency output. The unit also includes an optical-to-electrical conversion circuit that converts optical signals received at the optical input into radio frequency signals, a directional coupler that is coupled to an output of the optical-to-electrical conversion circuit and a radio frequency receiver that is coupled to a first output of the directional coupler. The radio frequency receiver receives radio frequency signals input through the optical input. The unit also includes a controller that is coupled to the radio frequency receiver, and a filter circuit that is coupled to a second output of the directional coupler. The filter circuit includes multiple signal paths that filter out signals in different frequency ranges. Switches are provided that select one of the signal paths through the filter circuit. These switches are controlled in response to data contained in the radio frequency signal. The controller is configured to generate control signals that control the settings of at least some of the switches based at least in part on a filter control signal received through the optical input.
1. An addressable optical network interface unit (“NIU”), comprising:
an optical input that is configured to connect to the cable television network;
a radio frequency output that is coupled to a subscriber premise;
an optical-to-electrical conversion circuit that is configured to convert optical signals received at the optical input into radio frequency signals;
a first directional coupler that is coupled to an output of the optical-to-electrical conversion circuit;
a radio frequency receiver that is coupled to a first output of the first directional coupler, the radio frequency receiver being configured to receive a radio frequency signal input through the optical input;
a controller that is coupled to the radio frequency receiver;
a filter circuit that is coupled to a second output of the first directional coupler, the filter circuit including a plurality of signal paths and a first filter that is on a first of the plurality of signal paths that filters out signals in a first range of frequencies and a second filter that is on a second of the plurality of signal paths that filters out signals in a second range of frequencies;
a second directional coupler that is interposed between the first output of the first directional coupler and the radio frequency receiver; and
a plurality of switches that select one of the plurality of signal paths through the filter circuit, wherein the plurality of switches are controlled in response to data contained in the radio frequency signal,
wherein the controller is configured to generate a plurality of control signals that control the settings of at least some of the plurality of switches based at least in part on filter control signal received through the optical input, and
wherein a first output of the second directional coupler is part of a feedback loop that controls an adaptive attenuator of the optical-to-electrical conversion circuit, and a second output of the second directional coupler is coupled to an input of the radio frequency receiver.
2. The addressable optical NIU of claim 1 , wherein a third of the plurality of signal paths in the filter circuit bypasses both the first and second filters.
3. The addressable optical NIU of claim 2 , wherein the first filter comprises a high pass filter and wherein the second filter comprises a band pass filter.
4. The addressable optical NIU of claim 2 , wherein a first of the plurality of signal paths through the filter circuit passes signals in the downstream frequency band from the cable television network to the subscriber premise while attenuating signals in the upstream frequency band from the subscriber premise to the cable television network, wherein a second of the plurality of signal paths through the filter circuit passes signals in selected frequency ranges of the downstream frequency band from the cable television network to the subscriber premise and passes signals in selected frequency ranges in the upstream frequency band from the subscriber premise to the cable television network, and wherein a third of the plurality of signal paths through the filter circuit bypasses passes all signals in the downstream frequency band from the cable television network to the subscriber premise and all signals in the upstream frequency band from the subscriber premise to the cable television network.
5. The addressable optical NIU of claim 1 , wherein the filter circuit comprises a plug-in filters circuit that is removably coupled to the addressable tap unit.
6. The addressable optical NIU of claim 5 , further comprising an alternate communications path between the optical input and the radio frequency output that bypasses the filter circuit, wherein the addressable optical NIU is configured so that signals incident at the radio frequency input traverse the alternate communications path if the plug-in filter circuit is not installed in the addressable optical NIU.
7. The addressable optical NIU of claim 1 , wherein the filter circuit includes a signal path that passes a frequency band associated with digital telephone emergency service while blocking at least a portion of the remainder of the frequency band associated with digital telephone emergency service.
8. The addressable optical NIU of claim 1 , wherein the filter circuit comprises a bandpass filter that passes signals in at least some of a 60-110 MHz frequency range.