Cable modem system with sample and packet synchronization
First Claim
1. A sample and packet synchronization subsystem interfaced between a cable modem system and a plurality of bit-rate sampled data transmission devices, the sample and packet synchronization subsystem comprising:
- a transmit analog-to-digital/receive digital-to-analog converter sub-system, including respective buffers for storing digital sampled data, the respective buffers being coupled between a multiplexer/demultiplexer and respective standard code/decode and subscriber loop interface circuits, each standard code/decode and subscriber loop interface circuit being coupled to a respective bit-rate sampled data transmission device; and
a digital signal processing subsystem, interfaced between the cable modem system and the transmit analog-to-digital/receive digital-to-analog converter sub-system, for transmission and reception through the cable modem system to and from a packet recipient, the digital signal processing subsystem;
determining unsolicited cable modem system grant arrivals in response to a request from the bit-rate sample data transmission device;
synchronizing the storing of sampled packets with the unsolicited cable modem system grant arrivals; and
transmitting to the cable modem system upon receipt of an unsolicited cable modem system grant arrival, currently stored sampled packets for further transmission to the packet recipient over the cable modem system.
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Accused Products
Abstract
A method for communicating information is disclosed wherein a time slot is allocated in a time division multiple access system for a transmission from a subscriber to a headend. Synchronization of a clock of the subscriber with respect to a clock of the headend is enhanced using a message transmitted from the headend to the subscriber which is indicative of an error in a subscriber transmission time with respect to the time slot. A feedback loop process is used to determine at least one of fractional symbol timing correction and carrier phase correction of a transmission from the subscriber to the headend. Filter coefficients are generated at the headend from a ranging signal transmitted from the subscriber to the headend and transmitting the filter coefficients from the headend to the subscriber, the filter coefficients being used by the subscriber to compensate for noise in a transmission from the subscriber to the headend.
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Citations
5 Claims
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1. A sample and packet synchronization subsystem interfaced between a cable modem system and a plurality of bit-rate sampled data transmission devices, the sample and packet synchronization subsystem comprising:
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a transmit analog-to-digital/receive digital-to-analog converter sub-system, including respective buffers for storing digital sampled data, the respective buffers being coupled between a multiplexer/demultiplexer and respective standard code/decode and subscriber loop interface circuits, each standard code/decode and subscriber loop interface circuit being coupled to a respective bit-rate sampled data transmission device; and a digital signal processing subsystem, interfaced between the cable modem system and the transmit analog-to-digital/receive digital-to-analog converter sub-system, for transmission and reception through the cable modem system to and from a packet recipient, the digital signal processing subsystem; determining unsolicited cable modem system grant arrivals in response to a request from the bit-rate sample data transmission device; synchronizing the storing of sampled packets with the unsolicited cable modem system grant arrivals; and transmitting to the cable modem system upon receipt of an unsolicited cable modem system grant arrival, currently stored sampled packets for further transmission to the packet recipient over the cable modem system. - View Dependent Claims (2, 3, 4, 5)
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Specification