Inventors:
Charles J. Naegeli - Montara CA
Alejandro H. Schwartzman - San Jose CA
Xiong Yang - Fremont CA
Assignee:
Cisco Technology, Inc. - San Jose CA
International Classification:
H04N 7173
US Classification:
725120, 725111, 725124, 725125, 725126, 348192, 348193, 375224, 375227, 370437, 455 62, 455 63
Abstract:
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.