Apparatus and method for digital modulation
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsTeruaki Hasegawa, Takaaki Konishi
Life of this patent
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Abstract
A first interpolation section 14 and a second interpolation section 24 perform sampling on input data Id4 and Qd4 having a sampling frequency fover so that resulting data will have a sampling frequency fsamp, which is equal to an operating clock frequency of a digital-to-analog converter, which is an output destination. In the above manner, the data is interpolated. At this time, the first interpolation section 14 and the second interpolation section 24 perform interpolation using a frequency ratio between the sampling frequency fover and the sampling frequency fsamp. Then,output data Id5 and Qd5 having the sampling frequency fsamp is outputted to a quadrature modulation section 31.
Claims14
A digital modulation apparatus for subjecting in-phase component data and quadrature component data to quadrature modulation and producing output with a predetermined output frequency, the apparatus comprising:
- a first filter for performing bandwidth limitation on the in-phase component data using a first sampling frequency, which is an integral multiple of a symbol frequency of the in-phase component data;
- a second filter for performing oversampling on data outputted from the first filter using a second sampling frequency, which is an integral multiple of the first sampling frequency;
- a first interpolation section for interpolating data outputted from the second filter so that resulting data will have the predetermined output frequency;
- a third filter for performing bandwidth limitation on the quadrature component data using the first sampling frequency, which is an integral multiple of a symbol frequency of the quadrature component data;
- a fourth filter for performing oversampling on data outputted from the third filter using the second sampling frequency, which is an integral multiple of the first sampling frequency;
- a second interpolation section for interpolating data outputted from the fourth filter so that resulting data will have the predetermined output frequency;
- and
- a quadrature modulation section for subjecting data outputted from the first interpolation section and data outputted from the second interpolation section to digital quadrature modulation, and outputting resulting data.
A digital modulation method for subjecting in-phase component data and quadrature component data to quadrature modulation and producing output with a predetermined output frequency, the method comprising:
- a first filtering step for performing bandwidth limitation on the in-phase component data using a first sampling frequency, which is an integral multiple of a symbol frequency of the in-phase component data;
- a second filtering step for performing oversampling on data subjected to the bandwidth limitation by the first filtering step, using a second sampling frequency, which is an integral multiple of the first sampling frequency;
- a first interpolation step for interpolating data subjected to oversampling by the second filtering step so that resulting data will have the predetermined output frequency;
- a third filtering step for performing bandwidth limitation on the quadrature component data using the first sampling frequency, which is an integral multiple of a symbol frequency of the quadrature component data;
- a fourth filtering step for performing oversampling on data subjected to the bandwidth limitation by the third filtering step, using the second sampling frequency, which is an integral multiple of the first sampling frequency;
- a second interpolation step for interpolating data subjected to oversampling by the fourth filtering step so that resulting data will have the predetermined output frequency;
- and
- a quadrature modulation step for subjecting data outputted from the first interpolation step and data outputted from the second interpolation step to digital quadrature modulation, and outputting resulting data.
Dependencies are inferred from the claim text.