Testing an upstream path of a cable network
First Claim
1. A method of testing an upstream path of a cable network, the method comprising:
- receiving, via the upstream path of the cable network, upstream data packets at a headend, wherein the upstream data packets are pre-equalized for transmission to the headend and include a test packet;
filtering, by a packet duration filter at the headend, the upstream data packets and passing, though the filter, the test packet determined to have a length equal to a target packet length;
determining, at the headend, signal quality information for the upstream path based on the filtered test packet, wherein the signal quality information includes a measured in-band frequency response;
correcting the measured in-band frequency response to account for pre-equalization of the upstream data packets; and
communicating the signal quality information, including the corrected in-band frequency response, to a test instrument.
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Accused Products
Abstract
An apparatus and method for testing an upstream path of a cable network are disclosed. The upstream path is tested by capturing and analyzing upstream data packets generated by a specific terminal device. A test instrument is connected at a node of the cable network. The test instrument establishes a communication session with the headend, informing the headend of an identifier of the device that will generate the test upstream data packet. The test upstream data packet is captured and analyzed at the headend, so that the results of the analysis can be communicated back to the test instrument. To speed up the packet capturing and filtering process, the upstream data packets can be pre-filtered based on packet duration and/or arrival time.
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Citations
20 Claims
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1. A method of testing an upstream path of a cable network, the method comprising:
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receiving, via the upstream path of the cable network, upstream data packets at a headend, wherein the upstream data packets are pre-equalized for transmission to the headend and include a test packet; filtering, by a packet duration filter at the headend, the upstream data packets and passing, though the filter, the test packet determined to have a length equal to a target packet length; determining, at the headend, signal quality information for the upstream path based on the filtered test packet, wherein the signal quality information includes a measured in-band frequency response; correcting the measured in-band frequency response to account for pre-equalization of the upstream data packets; and communicating the signal quality information, including the corrected in-band frequency response, to a test instrument. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of testing an upstream path of a cable network, the method comprising:
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receiving, at a headend, an upstream data packet generated by a terminal device connected to the cable network, wherein the upstream data packet includes a test packet; filtering, by a packet duration filter at the headend, the received upstream data packet and passing the test packet through the packet duration filter; demodulating the test packet and scanning the demodulated test packet to identify a test request and a device identifier identifying the terminal device; determining, at the headend, signal quality information for the terminal device based on the demodulated test packet; receiving, from the terminal device, at least one upstream pre-equalization coefficient used by the terminal device to generate the upstream data packet; and correcting the determined signal quality information to account for pre-equalization of the upstream data packet using the received at least one upstream pre-equalization coefficient. - View Dependent Claims (12, 13)
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14. A system for testing an upstream path of a cable network, the system comprising:
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test logic disposed at a headend of the cable network, the test logic including; a communication circuit for receiving, via the upstream path of the cable network; upstream data packets including a test packet generated at a regular time interval by a terminal device connected to a node associated with the upstream path of the cable network; and a test request message to obtain signal quality information associated with the terminal device connected to the upstream path of the cable network; and a packet duration filter to filter the upstream data packets to identify the test packet arriving at the regular time interval and having a packet length of a target packet length; and a processor to; determine the signal quality information for the upstream path of the cable network associated with the terminal device in response to receiving the test request message, wherein the signal quality information includes a measured in-band frequency response; and correct the measured in-band frequency response to account for pre-equalization of the upstream data packets. - View Dependent Claims (15, 16, 17)
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18. An apparatus for testing an upstream path of a cable network, the apparatus comprising:
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a packet generator to generate, at a regular time interval, a test packet of a packet length no more than a predetermined value based on a probability distribution of upstream packet lengths in the cable network; a pre-equalization circuit coupled to the packet generator to pre-equalize the test packet; a communication circuit to communicate pre-equalization coefficients to a headend of the cable network, and to receive pre-equalized signal quality information from the headend; and a display to display the received pre-equalized signal quality information, wherein the received pre-equalized signal quality information from the headend includes a frequency response measured at the headend based on the test packet, and wherein the frequency response is corrected at the headend for pre-equalization applied at the apparatus using the pre-equalization coefficients communicated to the headend by the apparatus. - View Dependent Claims (19, 20)
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Specification