Assessment and improvement of the capabilities of a window correlator to model GPS multipath phase errors

Betaille, David; Cross, PA; Euler, H.-J.

doi:10.1109/taes.2006.1642583

Cited by 29 publications

(10 citation statements)

References 8 publications

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Section: Software-based Multipath Mitigation Techniquesmentioning

confidence: 99%

“…An example of the raw SNRs for the satellite PRN01 in the LCPC dataset is shown in Figure 4 and the extracted multipath contaminated SNRs obtained by Equation (1) are shown in Figure 5, note the sinusoidal phase multipath pattern from about GPS seconds 200 000 to 204 000. The angular frequency of the multipath error is the output from ALNF and the estimated multipath frequency is then used to estimate the argument and amplitude of the multipath error in an Adaptive Comb Filter (ACF), which is described in (Händel and Tichavský, 1994) and it is similar to the ALS described in (Comp and Axelrad, 1996) and (Bétaille, 2004). The multipath error is reproduced using the estimated argument and amplitude as follows: where Φ MP denotes the reproduced phase multipath error, k is the receiver dependent scale factor, which relates the SNR and phase multipath error, n denotes the counter of multipath errors (or reflectors which cause multipath) in the phase measurement, r denotes the total number of multipath errors (or reflectors which cause multipath) in the phase measurement, A denotes the estimated amplitude of the multipath error, and θ denotes the argument or phase of the multipath error.…”

Section: Software-based Multipath Mitigation Techniquesmentioning

confidence: 99%

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Investigations into Phase Multipath Mitigation Techniques for High Precision Positioning in Difficult Environments

Lau

Cross

2007

J. Navigation

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The modelling of most Global Navigation Satellite System (GNSS) errors/biases and developments of data processing techniques have been improved substantially since the birth of Global Positioning System (GPS), however, there has been much less progress in the improvement of phase multipath mitigation techniques. Multipath therefore remains one of the most important error sources in high precision GNSS positioning. This is because multipath is site-dependent and therefore cannot be eliminated by differencing techniques. Also multipath is highly dependent on satellite-reflector-antenna geometry, which usually causes rapid changes in phase multipath errors especially in Real-Time Kinematic (RTK) applications. Multipath mitigation for static antennas such as those at reference stations can be carried out by site calibration, averaging over long observation times, and through the estimation of the error using filtering based on signal-to-noise ratio (SNR) data. However, multipath mitigation for kinematic antennas is still very difficult today.Nevertheless, much research has been carried out on a particular class of phase multipath mitigation techniques: ones that can be applied within positioning algorithms (rather than incorporated into the receiver tracking loops or antennas). This paper investigates and further develops a number of state-of-the-art techniques in this category. They include phase multipath estimation using SNR data, phase multipath estimation through the use of closely spaced antennas, multipath mitigation stochastic models such as the satellite elevation angle model and SNR-based models (SIGMA-∊ model and our modified SNR-based model), and our own novel ray-tracing method. The techniques are tested with both real and simulated data, the real test datasets have been collected on the Laboratoire Central des Ponts et Chaussées (LCPC) testbed near Nantes in France, and on the campus of the University of Nottingham during SPACE data collection experiments.

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Section: Software-based Multipath Mitigation Techniquesmentioning

confidence: 99%

Section: Software-based Multipath Mitigation Techniquesmentioning

confidence: 99%

Investigations into Phase Multipath Mitigation Techniques for High Precision Positioning in Difficult Environments

Lau

Cross

2007

J. Navigation

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“…Ray et al (2001) and Lau and Cross (2006a) describe antenna array techniques based on the geometric correlation of multipath errors at closely spaced antennas. Bétaille et al (2006) describe a receiver based technique, called the phase multipath mitigation window that relies on the gated correlator. This technique can effectively mitigate multipath with the differential path delay of more than 7.5 m. A similar technique, called vision correlator, is described in Fenton and Jones (2005).…”

Section: Introductionmentioning

confidence: 99%

Wavelet packets based denoising method for measurement domain repeat-time multipath filtering in GPS static high-precision positioning

Lau

2016

GPS Solut

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Repeatable satellite orbits can be used for multipath mitigation in GPS-based deformation monitoring and other high-precision GPS applications that involve continuous observation with static antennas. Multipath signals at a static station repeat when the GPS constellation repeats given the same site environment. Repeat-time multipath filtering techniques need noise reduction methods to remove the white noise in carrier phase measurement residuals in order to retrieve the carrier phase multipath corrections for the next day. We propose a generic and robust three-level wavelet packets based denoising method for repeat-time-based carrier phase multipath filtering in relative positioning; the method does not need tuning to work with different data sets. The proposed denoising method is tested rigorously and compared with two other denoising methods. Three rooftop data sets collected at the University of Nottingham Ningbo China and two data sets collected at three Southern California Integrated GPS Network high-rate stations are used in the performance assessment. Test results of the wavelet packets denoising method are compared with the results of the resistor-capacitor (RC) low-pass filter and the singlelevel discrete wavelet transform (DWT) denoising method. Multipath mitigation efficiency in carrier phase measurement domain is shown by spectrum analysis of two selected satellites in two data sets. The positioning performance of the repeat-time-based multipath filtering techniques is assessed. The results show that the performance of the three noise reduction techniques is about 1-46 % improvement on positioning accuracy when compared with no multipath filtering. The statistical results show that the wavelet packets based denoising method is always better than the RC filter by 2-4 %, and better than the DWT method by 6-15 %. These results suggest that the proposed wavelet packets based denoising method is better than both the DWT method and the relatively simple RC low-pass filter for noise reduction in multipath filtering. However, the wavelet packets based denoising method is not significantly better than the RC filter.

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“…sliding window method and discrete wavelet method are introduced in this paper. The results of calculation indicate that discrete wavelet transform can decrease the error caused by GPS time receiver j itter effectively.The main factor to influence synchronization between time transmission receiver and ground atomic clock is: Doppler frequency excursion, ionosphere, troposphere and the receiver itself [2][3][4] . So it has time transmit error in the receiver.…”

mentioning

confidence: 99%

“…The main factor to influence synchronization between time transmission receiver and ground atomic clock is: Doppler frequency excursion, ionosphere, troposphere and the receiver itself [2][3][4] . So it has time transmit error in the receiver.…”

mentioning

confidence: 99%

GPS time transfer smooth using discrete wavelet

Huang¹,

Zu²

2009

2009 International Conference on Mechatronics and Automation

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Time service is the precondition of precise navigation in radio navigation system, the cesium atomic clock of high stability is used in this system as frequency reference and GPS time receiver is used. To solve the problem of system synchronize error caused by satellite movement , Doppler frequency shift, ionosphere refraction, etc. sliding window method and discrete wavelet method are introduced in this paper. The results of calculation indicate that discrete wavelet transform can decrease the error caused by GPS time receiver j itter effectively.The main factor to influence synchronization between time transmission receiver and ground atomic clock is: Doppler frequency excursion, ionosphere, troposphere and the receiver itself [2][3][4] . So it has time transmit error in the receiver. Discrete wavelet is used to deal with the time difference measured by the time counter in this paper, using signal decompose and destruction treat the difference between atomic clock and time transmission receiver to decrease system position error caused by GPS time receiver. II. SYST EM CONSTITUTION Ind ustria l Computer IOMllz Cesi um atomic clock Sig na l ge nerator l PPS IPPS Cou nter PM668 1 Hig h speed compara tor GPS time receiver , --_ _-----, IPI'S , -----, Fig. I Structure of time synchronization partTime synchronization trigger is a tim e synchronization equipment in the navigation system, the equipment is connected with the GPS time receiver and atomic clock, the main function of the equ ipment is to choose time synchronization standard, the trigger generate two channel signals of the same frequency and steep rising edge pulse through trigger circuit according to the PPS from time synchronization standard. One of the channel is connect to atomic clock for synchronization, the other is connected to the high speed counter in order to measure the synchronize difference between the atomic and the time standard.Because each synchronized atomic clock and GPS receivers are at the different location and work in the different environment, after the GPS receiver time transferring, the The synchronization part structure in radio navigation system shows in Fig.l. The GPS receiver PPS signal is used as time standard in the synchronization part and the GPS pulse signal is disposed to a steep rising edge pulse through the synchronization trigger, then connected with atomic clock synchronization port, providing precise time standard to the system. Sate llite /Ĩ . INTRODUCTIONThe position of receiver is derived by its distances to different transmitting stations and the distances are measured by the delays between the transmitting stations and the receiver of the radio signals in radio navigation system. In reality the delay times are derived by the signal phase difference after propagation from different transmitting stations. Radio wave transmits at the speed of light that means one nanosecond synchronization error in transmitting station will equivalent to 0.3 meter distance measuring error in the receiver. Therefore time synchroniz...

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Assessment and improvement of the capabilities of a window correlator to model GPS multipath phase errors

Cited by 29 publications

References 8 publications

Investigations into Phase Multipath Mitigation Techniques for High Precision Positioning in Difficult Environments

Investigations into Phase Multipath Mitigation Techniques for High Precision Positioning in Difficult Environments

Wavelet packets based denoising method for measurement domain repeat-time multipath filtering in GPS static high-precision positioning

GPS time transfer smooth using discrete wavelet

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