Pulse or digital communications – Repeaters – Testing
Patent
1997-11-21
1999-10-05
Pham, Chi H.
Pulse or digital communications
Repeaters
Testing
375343, 375208, 370320, H04B 1500, H04K 100, H04L 2730
Patent
active
059635827
ABSTRACT:
A technique for minimizing or eliminating the effect of multipath signals in a receiver processing pseudorandom (PRN) code signals, such as in a global positioning system (GPS) receiver. The presence of multipath signals adversely affects both code measurements and carrier phase measurements of received PRN signals. One aspect of the invention provides for improved code tracking in the presence of multipath signals, by sampling the received code with a multipath mitigation window (MMW) (FIG. 25D) that results in a code error function (FIG. 25F) that reduces or eliminates the multipath effects. The MMW, which may be any of a number of preferred waveforms (FIGS. 35B-35E), provides a code error function that varies in opposite directions from zero at a desired tracking point (402), but assumes a nearly zero value when the MMW is advanced from the tracking or synchronization point by more than a small fraction of a code chip. Because of this nearly zero code error value on the early side of the desired tracking point, delayed multipath signals will have a corresponding code error function that is nearly zero (FIG. 25F) at the desired tracking point of the directly received signals, and the multipath signals will, therefore, have little or no effect on the desired tracking point and on code synchronization. The effects of multipath signals on carrier phase measurements are minimized by sampling the received signals, together with their possible multipath components, before and immediately after code transitions (vectors A and B, respectively). The vector relationship of the directly received (D) and multipath (M) signals is such that performing a vector average of the two types of samples (A and B) produces the directly received signal (D) and its correct phase, with many, if not all, of the multipath components (M) eliminated.
REFERENCES:
patent: 4754465 (1988-06-01), Trimble
patent: 4807256 (1989-02-01), Holmes et al.
patent: 4821294 (1989-04-01), Thomas, Jr.
patent: 4894842 (1990-01-01), Broekhoven et al.
patent: 5101416 (1992-03-01), Fenton et al.
patent: 5390207 (1995-02-01), Fenton et al.
patent: 5450448 (1995-09-01), Sheynblat
Heal Noel F.
Leica Geosystems Inc.
Pham Chi H.
Webster Bryan
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