发明授权
- 专利标题: Adaptive multipath equalization
- 专利标题(中): 自适应多径均衡
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申请号: US277150申请日: 1994-07-19
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公开(公告)号: US5630208A公开(公告)日: 1997-05-13
- 发明人: Per Enge , Dominic Farmer , John F. Schipper
- 申请人: Per Enge , Dominic Farmer , John F. Schipper
- 申请人地址: CA Sunnyvale
- 专利权人: Trimble Navigation Limited
- 当前专利权人: Trimble Navigation Limited
- 当前专利权人地址: CA Sunnyvale
- 主分类号: H04B7/005
- IPC分类号: H04B7/005 ; H04B1/10
摘要:
Method and apparatus for using a plurality of correlators to improve an estimate of direct signal arrival time by identifying features of a correlation function at and adjacent to the correlation peak. In a first embodiment, the errors in location of the center point of a correlation function R(.tau.), formed by the incoming composite signal and a stored copy of the expected signal, are assumed to be strongly correlated for narrow sample spacing and wide sample spacing of the correlation function. In a second embodiment, multipath signal strengths and phases are estimated, using multiple sampling of the correlation function R(.tau.). This approach assumes that path delays of the direct signal and of the multipath signals can be determined separately. Path delays can be determined by any of at least three approaches: (1) identification of slope transition points in the correlation function; (2) Cepstrum processing of the received signal, using Fourier transform analysis; and (3) use of a grid of time points on the correlation function domain, and identification of time values, associated with certain solution parameters of the least mean squares analysis that have the largest absolute values, as times of arrival of the direct and multipath signals. Separate identification of multipath time delays reduces the least mean squares analysis to a linear problem. A modified signal is constructed, with the multipath signal(s) approximately removed from the incoming composite signal. This modified signal allows a better estimate of the arrival time of the direct signal.
公开/授权文献
- US4925990A Process for the preparation of unsaturated alcohols 公开/授权日:1990-05-15
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