发明名称 |
PSK modem system with improved demodulation reliability |
摘要 |
A modem system is disclosed which has an improved reliability of detection of PSK data using a simple signal delay detection scheme. A transmission signal is produced which has a phase reference portion provided at at least one of the front and rear portions of a time slot. In a first half of the remaining portion of the time slot the phase of the transmission signal changes stepwise in a first predetermined direction for a "mark" state while in a second half of the remaining portion it changes stepwise back to the reference value. For a "space" state the phase changes stepwise in a second predetermined direction, opposite the first, in the first half of the remaining portion and then in the second half it changes stepwise back to the reference value. In a second aspect of the invention only one of the two digital states causes a corresponding phase change while for the other state the transmission signal retains the phase reference value throughout the time slot.
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申请公布号 |
US4807251(A) |
申请公布日期 |
1989.02.21 |
申请号 |
US19870076173 |
申请日期 |
1987.07.21 |
申请人 |
SUMITOMO ELECTRIC INDUSTRIES, LTD. |
发明人 |
SHIBANO, YOSHIZO |
分类号 |
H04L27/20;H04L27/233;(IPC1-7):H04L27/18 |
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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