| 摘要 |
PROBLEM TO BE SOLVED: To provide a GMSK modulation circuit that can surely attain a phase transition quantity of 90-degrees for one symbol period even when data are changing. SOLUTION: In a GMSK modulation circuit where a Gaussian filter 3 receives an input data signal, an output signal from the Gaussian filter 3 is given to a voltage controlled oscillator 5 whose modulation index is 0.5, where MSK modulation is applied to the signal with the oscillator 5, a gain adjustment device 4 is placed to a stage after the Gaussian filter 3. The gain of the gain adjustment device 4 is controlled so that the gain is controlled to be unity when the signs of two consecutive symbols are the same and the gain is controlled in a way that the phase transition quantity for one symbol period is 90 degrees when the signs are different.
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