| 摘要 |
PROBLEM TO BE SOLVED: To reduce the calculating burden of a modulating signal generator and also to simplify the constitution of the generator by generating a state variable from a set of bits included in an input data stream, generating an address pointer from the state variable, retrieving the calculated numeric value corresponding to the filter output out of a memory and obtaining a modulating signal through the addition/subtraction of the said numeric value. SOLUTION: A modulating device 200 is available in a digital system and provided with a differential state encoder 202 and a complex number sample generator 204. The generator 204 uses the past value of state variables BE, BQ and BI to generate a multiple bit digital complex number sample DI+jDQ at a sampling speed of a symbol speed. The generator 204 is stored in a reference table memory 206. Then the generator 204 uses those state variables as addresses and also uses the past value of a clock signal to retrieve the output value of filters which are stored in one or more reference tables stored in a reference table memory 206.
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