| 摘要 |
Techniques for formation of an autocorrelation difference function of an incoming digital signal that reduce the effects of presence of a multipath signal or of noise in an incoming digital composite signal, including direct and multipath signals are disclosed. The received digital signal has a bit value transition interval of length DELTA tau chip. Two or three consecutive bit values bn-2, bn-1 and bn of the direct (ideal) signal are examined. If a test condition for these bit values is satisfied, a first non-uniform weighting function w1(t) is used to compute the contribution of a time interval In = {t'|tn-1 + DELTA <t' </=tn + DELTA }, where DELTA is a selected value satisfying 0 </= DELTA < DELTA tau chip, to first and second autocorrelation functions, AC#( tau ;E) and AC#( tau ;L), with respective first and second time shifts tau = tE and tau = tL(>tE). If the test condition is not satisfied, a second weighting function w1 &cir& (t) is used to compute the contribution of the time interval In to the first and second autocorrelation functions. An autocorrelation difference function DELTA AC#( tau ) = AC#( tau ;E) - AC#( tau ;L) is formed in which the effects of noise or of multipath signals is suppressed, relative to these effects in a conventionally computed autocorrelation difference function.
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