Cisco Technology, Inc.

Alejandro Schwartzman

Charles J Naegeli

Hung-San Chen

Timothy Finan

Paul Lafferty

Xiong Yang

Weiliang Zhu

Mark E Millet

Chrisanto Leano

Wei-Sing Chen

Glenn E Lee

Eric Youngman

Steven A Jacobson

Methods and apparatus are provided for allowing an operating system to automatically configure and operate multiple types of the same component. According to various embodiments, characteristic information associated with a particular component, such as a tuner, can be written to a nonvolatile memory. An operating system can be configured to read characteristic information from the nonvolatile memory associated with the component. In one example, the characteristic information includes power characteristics associated with the component. By providing characteristic information in a nonvolatile memory, a single version of an operating system can configure and operate many different versions and types of the same component.

Methods and apparatus for allowing component interchangeability

Methods and apparatus for disabling and enabling the receiver circuitry of a cable modem connected to a cable network headend are described. The cable network headend transmits a message to the cable modem to disable the receiver circuitry when a cable network headend determines that the cable modem is idle. The cable modem listens for messages on the cable network during activation windows between periodic intervals. Messages arriving during these activation windows can enable the receiver circuitry of the cable modem as well as synchronize the clocks of the cable network headend and the cable modem. The cable modem can also self enable its receiver circuitry and inform the cable network headend of its enabled state.

Methods and apparatus for enabling and disabling cable modem receiver circuitry

Methods and apparatus are provided for determining transmission power levels. The power characteristics of a cable modem family are determined by testing cable modems in a cable modem family with various downstream frequencies and transmission power levels to determine internal gain levels. The power characteristics of the cable modem family can then be stored in an efficient manner in each cable modem by using interpolation. The individual cable modem can then be characterized by testing the cable modem with a limited set of downstream frequencies and transmission power levels to determine an internal gain level offset for that particular cable modem. With the power characteristics table, internal gain level offset, and interpolation, transmission power levels can be determined during network operation when downstream frequencies and internal gain levels are known.

Methods and apparatus for determining transmission power levels

Apparatus, methods, and computer program products for utilizing a frequency channel determined to be unacceptably noisy by finding a cleaner, narrower bandwidth within the frequency channel. Initially data is received on a frequency channel at a CMTS, specifically an upstream receiver, and by a narrow bandwidth detector, connected to a processor also used by components in the CMTS. The narrow bandwidth detector performs a Fast Fourier Transform (FFT) on the frequency channel thereby creating multiple FFT points within the frequency channel. A clean bandwidth for transmitting data within the frequency channel is identified where the clean bandwidth is derived from a subset of FFT points from the full set of FFT points. The subset of FFT points are contiguous points that have a noise level below a predetermined noise threshold.

Method and apparatus for locating a cleaner bandwidth in a frequency channel for data transmission

Apparatus and methods are disclosed for reducing noise leakage on the upstream channel from a cable modem. Noise leakage from cable modems, such as from a persistently enabled amplifier or other components in the modem, can accumulate on an upstream channel and reduce the overall signal-to-noise ratio of signals sent to the headend. In order to significantly reduce such noise leakage and to provide termination of the cable plant in the modem when the modem is not transmitting data, a cable modem arranged to improve its isolation is disclosed. The modem contains an upstream transmitter having a control line on which the upstream transmitter can emit a control signal. The modem also includes a switch component capable of being enabled and disabled by the control signal on the control line. The control signal from the upstream transmitter to the switch component enables the switch component thereby allowing a data signal to be transmitted on an upstream channel. The switch component includes two switches. One switch is a series switch used to enable and disable the transmission of data. Another switch is a shunt for providing termination of the cable plant. The cable modem also includes an amplifier for amplifying the data signal from the upstream transmitter before being transmitted on the upstream channel.

Method and apparatus for reducing noise leakage from a cable modem

Transitions among different upstream frequency channels in a cable television plant in order to transmit data occur while considering the noise level of the upstream frequency channel presently being used to transmit data. By taking into account the noise level of the presently used upstream frequency channel, the CMTS in a cable plant can make a more intelligent decision as to whether it is worthwhile changing the upstream frequency channel for a group of cable modems. A spectrum analyzer determines the noise level of a presently used frequency channel. A bit error rate for the present frequency channel is detected. The spectrum analyzer then determines whether the bit error rate exceeds a threshold value. Is so, it is then determined whether the noise level of the present frequency channel is greater than or less than the noise level of another frequency channel having the lowest noise level plus a buffer noise value. If the present noise level is greater, a transition is made to the other frequency channel with the lower noise level. If not, the cable plant continues using the present frequency channel. The noise level of the presently used frequency channel is measured at the CMTS upon receipt of an empty data packet arriving at a known timing mark.

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San Jose, CA, United States of America

Alejandro Schwartzman