Pulse or digital communications – Receivers – Particular pulse demodulator or detector
Patent
1998-04-16
2000-07-04
Bocure, Tesfaldet
Pulse or digital communications
Receivers
Particular pulse demodulator or detector
375209, 375340, H04L 2706, H04K 100
Patent
active
060849274
ABSTRACT:
Method and apparatus for formation of an autocorrelation difference function of an incoming digital signal, with bit transition interval length .DELTA..tau..sub.chip, that reduces the effects of presence of a multipath signal in an incoming composite signal. First and second autocorrelation functions AC(.tau.;E;qE) and AC(.tau.;L;qL) are formed with respective first and second selected time shift values .tau.=t.sub.E and .tau.=t.sub.L, which replicate an estimate of an autocorrelation function AC(.tau.;P;qP) at an intermediate time shift value .tau.=t.sub.P that satisfies t.sub.E <t.sub.P <t.sub.L with t.sub.L -t.sub.E <2.DELTA..tau..sub.chip, and which depend upon one or more parameters qE and qL, respectively. Independently chosen, non-uniform weighting functions w1(t;qE) and w2(t;qL) are used for formation of the respective autocorrelation functions AC(.tau.;E;qE) and AC(.tau.;L;qL) that depend upon one or more parameters qE and qL. Reduction of non-multipath and/or noise effects is achieved by particular choices of weighting functions. The correlator spacing t.sub.L -t.sub.E may be narrow (e.g., .DELTA.t.sub.L-E .ltoreq.0.3.DELTA..tau..sub.chip) or may be any larger value, up to 2.DELTA..tau..sub.chip, with appropriate choice of the weighting functions w1 and w2.
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Bocure Tesfaldet
Schipper John
Trimble Navigation Limited
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