To provide a digital modulation system using an orthogonal code modified to reduce autocorrelation.
The digital modulation system uses the modified orthogonal code having reduced autocorrelation sidelobes to enhance multi-path performance and to simultaneously maintain cross-correlation property of this modified code. For example, this modified orthogonal code suppresses an autocorrelation level to a certain extent not to exceed a half length of this modified orthogonal code. In several embodiments, an M-ary orthogonal keying (MOK) system is used and this system modifies an orthogonal Walsh code by using a complementary code, thereby improving the autocorrelation property of the Walsh code. Thus, the multi-path performance of the M-ary orthogonal keying (MOK) system is enhanced and simultaneously, orthogonality of the Walsh code and the low autocorrelation property are maintained.
COPYRIGHT: (C)2005,JPO&NCIPI
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| JP6318927A | ||||
| JP8509590A |
Nobuaki Kato
Kazuo
Shinichi Usui
Takao Ochi
Teruhisa Motomiya
Asahi Shinmitsu