Signalling transition control in a modulated-signal communications system
First Claim
1. For use in a modulated signal communications system having a plurality of predefined signal states each representing a digital data symbol, a signal transition control system enabling a transition from one signal state to a next signal state to be executed in a smooth, bandwidth-efficient manner, comprising:
- means for receiving a stream of data symbols to be data modulated and transmitted through a data telecommunications medium and storing in succession consecutive pairs of the data symbols, each of the pairs including a previous data symbol and a next data symbol, the means for receiving and storing comprising a pair of data registers connected in common to a data strobe signal, an input of a first one of the data registers being connected to receive the data stream, and an input of a second one of the data registers being connected to an output of the first one of the data registers;
first means, responsive to the means for receiving and storing, for producing data describing a vector in signal space from the previous data symbol to the next data symbol, the first means for producing comprising a plurality of look-up-table memories including a scale look-up-table memory and an offset look-up-table memory, an output of the second one of the data registers and the output of the first data register being used to address the scale look-up-table memory, and the output of the second data register being used to address the offset look-up-table memory;
means for storing data representative of a desired shape of a transition from the previous data symbol to the next data symbol;
means for sequentially stepping through the data representative of the desired shape to cause the data to be presented at an output of the means for storing; and
second means, responsive to the first means for producing and to the means for storing, for producing data representing a transition from the previous data symbol to the next data symbol, the transition having the desired shape.
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Accused Products
Abstract
A signal transition control system for use in a modulated-signal communication system having a plurality of predefined signal states each representing a digital data symbol, enables a transition from one signal state to a next signal state to be executed in a smooth, bandwidth-efficient manner. The system includes circuitry for receiving a stream of data symbols and storing in succession consecutive pairs of the data symbols, each of the pairs including a last data symbol and a next data symbol, for producing data describing a vector in signal space from the last data symbol to the next data symbol, for storing data representative of a desired shape of a transition from the last data symbol to the next data symbol, means for sequentially stepping through the data representative of the desired shape, and for producing data representing a transition from the last data symbol to the next data symbol, the transition having the desired shape. The system is used to particular advantage in a number-controlled modulated oscillator that generates a signal having a numerically controlled frequency, a numerically controlled phase, a programmable shape, and a numerically controlled amplitude.
45 Citations
7 Claims
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1. For use in a modulated signal communications system having a plurality of predefined signal states each representing a digital data symbol, a signal transition control system enabling a transition from one signal state to a next signal state to be executed in a smooth, bandwidth-efficient manner, comprising:
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means for receiving a stream of data symbols to be data modulated and transmitted through a data telecommunications medium and storing in succession consecutive pairs of the data symbols, each of the pairs including a previous data symbol and a next data symbol, the means for receiving and storing comprising a pair of data registers connected in common to a data strobe signal, an input of a first one of the data registers being connected to receive the data stream, and an input of a second one of the data registers being connected to an output of the first one of the data registers; first means, responsive to the means for receiving and storing, for producing data describing a vector in signal space from the previous data symbol to the next data symbol, the first means for producing comprising a plurality of look-up-table memories including a scale look-up-table memory and an offset look-up-table memory, an output of the second one of the data registers and the output of the first data register being used to address the scale look-up-table memory, and the output of the second data register being used to address the offset look-up-table memory; means for storing data representative of a desired shape of a transition from the previous data symbol to the next data symbol; means for sequentially stepping through the data representative of the desired shape to cause the data to be presented at an output of the means for storing; and second means, responsive to the first means for producing and to the means for storing, for producing data representing a transition from the previous data symbol to the next data symbol, the transition having the desired shape. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification