Radio frequency characterization of cable plant and corresponding calibration of communication equipment communicating via the cable plant
First Claim
1. A bi-directional cable communication system configured to communicate information via a cable network, the cable communication system incorporating diagnostic and calibration logic, the cable communication system comprising:
- a first transceiver, coupled at a selected point of distribution of the cable network, that transmits a downstream test signal having predetermined characteristics on the cable network in a selected downstream channel at a predetermined power level, that receives corresponding downstream diagnostic information in a selected upstream channel, the downstream diagnostic information including a downstream power loss metric, and that calibrates downstream transmission power based on the downstream power loss;
a second transceiver, coupled to the cable network at a selected downstream location, that receives the downstream test signal in the selected downstream channel, that compares the received signal with the predetermined characteristics and power level to determine the downstream diagnostic information including a downstream power loss metric and a downstream noise level metric for the selected downstream channel, and that transmits the downstream diagnostic information in a selected upstream channel;
the second transceiver transmitting an upstream test signal with predetermined characteristics on the cable network in the selected upstream channel at a predetermined power level, that receives corresponding upstream power information in the downstream channel, and that calibrates upstream transmission power based on the upstream power information; and
the first transceiver receiving the upstream test signal, comparing the received upstream test signal with the predetermined characteristics and power level to determine corresponding upstream diagnostic information including an upstream power loss metric and an upstream noise level metric in the upstream channel, determining the upstream power information based on the upstream power loss metric, and transmitting the power information in the selected downstream channel.
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Abstract
A switch router and one or more gateways incorporating a diagnostic and calibration system that performs RF characterization of an underlying cable plant. The switch router is connected at a point of insertion or point of distribution and each gateway is located downstream, such as at corresponding subscriber locations. The switch router and each gateway sends a test signal with known characteristics and power level, and the receiving device determines noise level and power loss for the corresponding downstream and upstream channel pair. The power loss information is used to calibrate the power level of the transmitters. The noise levels are used to determine if the selected modulation schemes employed for normal communications is realizable. A frequency analysis, such as FFT or the like, is performed on the upstream test signal spectrum to derive valuable frequency information for the upstream channel or the entire upstream bandwidth.
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Citations
28 Claims
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1. A bi-directional cable communication system configured to communicate information via a cable network, the cable communication system incorporating diagnostic and calibration logic, the cable communication system comprising:
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a first transceiver, coupled at a selected point of distribution of the cable network, that transmits a downstream test signal having predetermined characteristics on the cable network in a selected downstream channel at a predetermined power level, that receives corresponding downstream diagnostic information in a selected upstream channel, the downstream diagnostic information including a downstream power loss metric, and that calibrates downstream transmission power based on the downstream power loss;
a second transceiver, coupled to the cable network at a selected downstream location, that receives the downstream test signal in the selected downstream channel, that compares the received signal with the predetermined characteristics and power level to determine the downstream diagnostic information including a downstream power loss metric and a downstream noise level metric for the selected downstream channel, and that transmits the downstream diagnostic information in a selected upstream channel;
the second transceiver transmitting an upstream test signal with predetermined characteristics on the cable network in the selected upstream channel at a predetermined power level, that receives corresponding upstream power information in the downstream channel, and that calibrates upstream transmission power based on the upstream power information; and
the first transceiver receiving the upstream test signal, comparing the received upstream test signal with the predetermined characteristics and power level to determine corresponding upstream diagnostic information including an upstream power loss metric and an upstream noise level metric in the upstream channel, determining the upstream power information based on the upstream power loss metric, and transmitting the power information in the selected downstream channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A communication system configured to communicate across a cable system having a point of distribution and at least one downstream subscriber cable link, the communication system configured to operate in a diagnostic and calibration mode, the communication system comprising:
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a switch router, coupled to the cable system at the point of distribution, that transmits a predetermined downstream test signal at a predetermined power level using a selected downstream channel, that receives corresponding downstream channel diagnostic information including downstream channel power loss, that calibrates transmission power for the downstream channel based on the downstream channel power loss, that receives an upstream test signal and determines corresponding upstream channel power loss and noise level, and that transmits corresponding upstream channel power information on the selected downstream channel; and
at least one gateway, each gateway coupled to a corresponding downstream subscriber cable link, each gateway transmitting a predetermined upstream test signal at a predetermined power level in a selected upstream channel, that receives corresponding upstream channel power information, that calibrates transmission power of the selected upstream channel based on the upstream channel power information, that receives a downstream test signal and determines downstream channel diagnostic information including downstream channel power loss and noise level, and that transmits the downstream channel diagnostic information in the selected upstream channel. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A method of characterizing a cable network and calibrating a bi-directional cable communication system, comprising:
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transmitting a downstream test signal from a point of distribution on the cable network in a selected downstream channel at a predetermined downstream power level, the downstream test signal having predetermined characteristics;
receiving the downstream test signal in the selected downstream channel at a downstream location;
determining a downstream power loss metric of the downstream channel by comparing a power level of the received downstream test signal with the predetermined downstream power level;
transmitting downstream diagnostic information including the downstream power loss and downstream noise level metrics in a selected upstream channel;
calibrating downstream transmit power at the point of distribution based on the downstream power loss metric;
transmitting an upstream test signal from the downstream location on the cable network in a selected upstream channel at a second predetermined power level, the upstream test signal having second predetermined characteristics;
receiving the upstream test signal in the selected upstream channel at the point of distribution;
determining an upstream power loss metric of the upstream channel by comparing a power level of the received upstream test signal with the predetermined upstream power level;
transmitting upstream power information in the selected downstream channel; and
calibrating upstream transmit power at the downstream location based on the upstream power information. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification