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.

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.

Abstract: 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.

Abstract: A network (10) includes a broadband customer service module (B-CSM) (20). The B-CSM (20) includes a plurality of feeder interface cards (FICs) (36) and optical line cards (OLCs) (38) which are coupled together through a midplane assembly (34) so that each FIC (36) couples to all OLCs (38) and each OLC (38) couples to all FICs (36) through junctor groups (68). A reference clock which oscillates at a frequency slower than the data rate is routed with payload data so that it receives delays similar to those imposed on the payload data due to processing. At second stage switching fabrics (50) where data need to be extracted from signals flowing within the B-CSM (20), a clock regeneration circuit (32) generates a master clock signal oscillating at twice the data rate and phase synchronized to a delayed reference clock.

Abstract: A network (10) includes a broadband customer service module (B-CSM) (20). The B-CSM (20) includes a plurality of feeder interface cards (FICs) (36) and optical line cards (OLCS) (38) which are coupled together through a midplane assembly (34) so that each FIC (36) couples to all OLCs (38) and each OLC (38) couples to all FICs (36) through junctor groups (68). The B-CSM (20) interfaces many OC-12 SONET feeders to many OC-12 SONET lines. Within the B-CSM (20) circuit switching is performed electrically at an STS-1 rate. A reference clock which oscillates at a frequency lower than the data rate is routed with payload data so that it receives delays similar to those imposed on the payload data due to processing. At second stage switching fabrics (50) where data need to be extracted from signals flowing within the B-CSM (20), a clock regeneration circuit (32) generates a master clock signal oscillating at twice the data rate and phase synchronized to a delayed reference clock.

Abstract: A broadband ISDN communication system (10) comprises a plurality of bit-serial synchronous time-division multiplexed ring networks (15) interconnected by a circuit switch (11). In each network, terminal equipment (14) is interfaced to a fiber-optic ring bus (12) by add/drop multiplexers (13). Single time slots (201) on the ring function as independently-assignable channels. Each time slot carries one bit at an 8 Kbps rate. Ring bandwidth is 45 Mbps. The circuit switch is a time-division multiplexed time-space switch. The time stage (301) comprises a plurality of time slot interchangers (TSI 303), one for each switch output port (306). Each TSI unit is connected to all switch input ports (305) and through the space stage to its corresponding output port. The space stage (302) is a time-multiplexed space stage. The switch is fully non-blocking and has broadcast capability. System bandwidth is dynamically allocated to users in single time slot (8 Kbps) increments, under control of a network manager (16).