发明名称 |
Digital modulation apparatus |
摘要 |
A quadrature phase modulator constructed by use of a simple digital circuit. Digital signals of sample data obtained by sampling outputs from a roll-off filter with a frequency four times a modulated carrier frequency are stored in an ROM, the outputs corresponding to all combinations of a plurality of successive bits of input data; the plurality of bits are set as an address, and a signal of an in-phase channel and a signal of a quadrature phase channel is alternately read from the ROM with a frequency equal to half the sampling frequency, then the obtained serial signals are subjected to a digital-to-analog conversion to obtain a quadrature phase modulated signal.
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申请公布号 |
US4680556(A) |
申请公布日期 |
1987.07.14 |
申请号 |
US19860850097 |
申请日期 |
1986.04.10 |
申请人 |
HITACHI, LTD. |
发明人 |
NAKAMURA, SHIGEKI;OHNISHI, MAKOTO;TAKAHASHI, YASUFUMI |
分类号 |
H04L27/20;(IPC1-7):H03C3/00 |
主分类号 |
H04L27/20 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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