| US 7,509,670 B1 | ||
| Method and apparatus for locating a cleaner bandwidth in a frequency channel for data transmission | ||
| Charles J. Naegeli, Montara, Calif. (US); Hung-San Chen, San Jose, Calif. (US); Alejandro H. Schwartzman, San Jose, Calif. (US); and Xiong Yang, Fremont, Calif. (US) | ||
| Assigned to Cisco Technology, Inc., San Jose, Calif. (US) | ||
| Filed on Apr. 03, 2003, as Appl. No. 10/407,345. | ||
| Application 10/407345 is a continuation of application No. 09/227991, filed on Jan. 08, 1999, granted, now 6,574,797. | ||
| Int. Cl. H04N 7/173 (2006.01) | ||
| U.S. Cl. 725—124 [725/125] | 36 Claims |
| 1. A system for utilizing a frequency channel for transmitting data upstream in a cable plant from one or more cable modems
to a cable modem termination system, the system comprising a narrow bandwidth detector, which comprises:
a memory;
a processor interface; and
a data processor configured to
analyze a single frequency channel of interest thereby creating a plurality of analysis points at different frequencies within
the frequency channel of interest;
identify a clean bandwidth for transmitting data within the single frequency channel of interest wherein the clean bandwidth
is derived from a set of analysis points from the plurality of analysis points within the single frequency channel; and
instruct the one or more cable modems in the cable plant to constrain their data transmissions to the clean bandwidth within
the frequency channel of interest;
wherein the data processor is further configured to:
compare a noise level of one of the plurality of analysis points to a predetermined noise level;
increment a counter if the noise level of the analysis point is below the predetermined noise level; and
save a value corresponding to the counter and reset the counter if the noise level of the analysis point is above the predetermined
noise level thereby storing one or more values corresponding to the counter.
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