发明授权
US5566214A Automatic noise normalization and reacquisition control for a QPSK
demodulator symbol tracking loop
失效
QPSK解调器符号跟踪循环的自动噪声归一化和重新获取控制
- 专利标题: Automatic noise normalization and reacquisition control for a QPSK demodulator symbol tracking loop
- 专利标题(中): QPSK解调器符号跟踪循环的自动噪声归一化和重新获取控制
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申请号: US491667申请日: 1995-06-19
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公开(公告)号: US5566214A公开(公告)日: 1996-10-15
- 发明人: Brian W. Kroeger , Jeffrey S. Baird
- 申请人: Brian W. Kroeger , Jeffrey S. Baird
- 申请人地址: PA Pittsburgh
- 专利权人: Westinghouse Electric Company
- 当前专利权人: Westinghouse Electric Company
- 当前专利权人地址: PA Pittsburgh
- 主分类号: H04L27/22
- IPC分类号: H04L27/22 ; H04L7/00
摘要:
A QPSK demodulator symbol tracking loop including automatic noise normalization and reacquisition control enables improved symbol tracking and acquisition during fading or intermittent channel conditions. A noise variance estimate is determined and the symbol tracking loop flywheels when the signal level dips below a flywheel threshold relative to the noise variance estimate during fading or intermittent channel conditions. Determination in advance of an absolute power level of the thermal noise floor of analog front end components is dispensed with and precise control of the gain and noise level of the analog front end components is not needed, thus simplifying design. A reacquisition mode is declared upon determination of an abrupt increase in signal level indicative of emergence from a fading condition or upon detection of an excessive symbol tracking error signal. During the reacquisition mode, the loop gain of the symbol tracking loop is temporarily increased to improve reacquisition time.
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