Effects of multipath and antenna on GPS observables

Zhuang, Weihua; Tranquilla, J.M.

doi:10.1049/ip-rsn:19951998

Cited by 20 publications

(9 citation statements)

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“…The phase center of the antenna varies with frequency and boresight angle. The axial ratio of the antenna which is an indicator of the amount of the rejection of a LHCP (reflected) signal varies with the frequency and the incident angle [13], [14]. Knowing the frequency dependant variation will help in calibrating for that effect.…”

Section: Group Delay Compensation When Both Ionospheric and Multipmentioning

confidence: 99%

Group delay compensation in AltBOC receivers to mitigate the effect of frequency selective propagation delay distortions

Shivaramaiah

Dempster

2010

IEEE/ION Position, Location and Navigation Symposium

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Abstract-This paper extends the Sub-carrier Phase Combination technique previously presented by the authors to mitigate the effect of frequency selective Radio Frequency (RF) propagation delay distortions in Alternate Binary Offset Carrier (AltBOC) receivers. Two major propagation delay distortion sources are considered: the ionosphere and multipath. Initial analysis shows that the ionospheric delay errors can be reduced to being comparable to the receiver impairments (when the error due to multipath is low) and the maximum multipath error (under low ionospheric distortions) can be reduced to half a meter. Under extremely high ionospheric delay distortions, the multipath delay error envelope, with the proposed technique, will suffer no change in the magnitude of the error except that the spatial characteristics are different. The underlying idea of the proposed technique is that difference in the phase delays of the E5a and E5b signal tracking is simply the slope of the phase response over the entire band and hence represents the group delay at the E5 center frequency of 1191.795 MHz. The group delay which appears as the code phase error for the E5 signal tracking, can thus be compensated except for the occurrence of higher order errors.

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Section: Group Delay Compensation When Both Ionospheric and Multipmentioning

confidence: 99%

Group delay compensation in AltBOC receivers to mitigate the effect of frequency selective propagation delay distortions

Shivaramaiah

Dempster

2010

IEEE/ION Position, Location and Navigation Symposium

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“…The discriminator function in mulitpath is given by, (1) =DC+ DelT where A is the signal amplitude, oc is the multipath-todirect signal amplitude ratio, d is the early-late correlator spacing, ATm is the multipath time delay relative to the direct path, and R(t) is the autocorrelation function of the C/A code. D is the multipath carrier phase offset due to both the delay ATm and the phase shift, AOm, induced by the reflector [8], with…”

Section: Performance Analysis For Coherentmentioning

confidence: 99%

Comparison of Average Performance of GPS Discriminators in Multipath

Liu

Amin

2007

2007 IEEE International Conference on Acoustics, Speech and Signal Processing - ICASSP '07

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Signal multipath in GPS leads to undesirable tracking errors and inaccurate ranging information. The extent of the tracking error in compromising the receiver performance depends on the multipath amplitude, delay, and phase relative to the direct path. The coherent discriminator and the noncoherent early-minus-late power discriminator offer different tracking accuracy and sensitivity to multipath parameters. In this paper, we develop analytical expressions of the average performance of the two discriminators over the multipath phase distribution and other propagation channel variables.

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“…Vector is modeled as a complex, circularly-symmetric, zero-mean Gaussian process that has an unknown and arbitrary spatial correlation matrix : 3 (5) For simplicity, the process is assumed to be temporally white.…”

Section: B Simplified Signal Modelmentioning

confidence: 99%

“…The previous ML estimator will be compared in Section VI with three other methods, which are outlined below. The first one consists in assuming that the steering vector of the LOSS is arbitrary and unknown along with the model in (4), (5). The minimization of (15) with respect to is trivial, and the ML time-delay estimate obtained using only a temporal reference is (20) The second method relies on the same simplified model as the ML estimator proposed in this paper but with the additional assumption that the noise is spatially white.…”

Section: B Simplified Signal Modelmentioning

confidence: 99%

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ML estimator and hybrid beamformer for multipath and interference mitigation in GNSS receivers

Seco-Granados

Fernandez–Rubio

Fernández‐Prades

2005

IEEE Trans. Signal Process.

104

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Abstract-This paper addresses the estimation of the code-phase (pseudorange) and the carrier-phase of the direct signal received from a direct-sequence spread-spectrum satellite transmitter. The signal is received by an antenna array in a scenario with interference and multipath propagation. These two effects are generally the limiting error sources in most high-precision positioning applications. A new estimator of the code-and carrier-phases is derived by using a simplified signal model and the maximum likelihood (ML) principle. The simplified model consists essentially of gathering all signals, except for the direct one, in a component with unknown spatial correlation. The estimator exploits the knowledge of the direction-of-arrival of the direct signal and is much simpler than other estimators derived under more detailed signal models. Moreover, we present an iterative algorithm, that is adequate for a practical implementation and explores an interesting link between the ML estimator and a hybrid beamformer. The mean squared error and bias of the new estimator are computed for a number of scenarios and compared with those of other methods. The presented estimator and the hybrid beamforming outperform the existing techniques of comparable complexity and attains, in many situations, the Cramér-Rao lower bound of the problem at hand.

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Effects of multipath and antenna on GPS observables

Cited by 20 publications

References 0 publications

Group delay compensation in AltBOC receivers to mitigate the effect of frequency selective propagation delay distortions

Group delay compensation in AltBOC receivers to mitigate the effect of frequency selective propagation delay distortions

Comparison of Average Performance of GPS Discriminators in Multipath

ML estimator and hybrid beamformer for multipath and interference mitigation in GNSS receivers

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