Cycle Slip Detection during High Ionospheric Activities Based on Combined Triple-Frequency GNSS Signals

Zhao, Dongsheng; Hancock, Craig M.; Roberts, Gethin Wyn; Jin, Shuanggen

doi:10.3390/rs11030250

Cited by 15 publications

(10 citation statements)

References 39 publications

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“…The most combinatorial optimizations have mainly aimed at the longer wavelength and lower level of observational noises [25]. However, the amplified ionospheric effects resulting from the combinations are hard to reasonably handle [26,27], and the large pseudorange error is another fatal flaw to successful CSD and CSR [28]. Thereby, we developed a GPS triple-frequency CSR method (GTCSR) to improve the CSR performance.…”

Section: Introductionmentioning

confidence: 99%

“…Second, compared to the existing step-by-step optimization on the GPS triplefrequency combination, GTCSR established a unified optimal model to achieve integrated optimization. In the existing step-by-step optimization, the first step was set to obtain the coefficients of the optimized combinations without regard to the ionospheric effect; then, the next step calculated the ionospheric scaling factors with the coefficients of the optimized combinations provided from the first step; and finally, the ionospheric amplifications were analyzed to select the final optimized combinations [23][24][25][26]. In contrast, GTCSR constructs a unified optimal model whose optimization objective has taken into account the influence of ionospheric delay, and minimizes the variance of the cycle slip combination at one time.…”

Section: Introductionmentioning

confidence: 99%

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Improved Cycle Slip Repair with GPS Triple-Frequency Measurements by Minifying the Influences of Ionospheric Variation and Pseudorange Errors

Dang

Yuan

et al. 2021

Remote Sensing

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In advance of precise positioning with phase data, cycle slip detection (CSD) is a basic work that should be implemented in phase data possessing. When the cycle slip occurred, cycle slip repair (CSR) can be taken to rebuild the continuity of phase data. Unfortunately, the large pseudorange errors can contaminate the combinations with the pseudoranges and phases such as the Hatch–Melbourne–Wubbena combination (HMW) and cause false CSD or wrong CSR results. On the other hand, the severe ionospheric time variation can deteriorate the epoch-difference geometry-free phase (GF), and tremendously interfere with the performances of CSD and CSR. To handle the aforementioned limitations, a global position system (GPS) triple-frequency CSR method (GTCSR) is proposed with two efficient treatments: (1) the significant ionospheric variations are corrected, and the influences from the residual ionospheric effects are minimized along with the observational noises; and (2) the impacts of large pseudorange errors are refrained by designing a discrimination function with a geometry-free and ionosphere-free phase to identify the correct cycle slip values. Consequently, CSR tests were conducted with three monitoring stations at different regions. First, during a strong geomagnetic storm, without correcting the ionospheric variation of CSR (WICSR) displayed obvious failures, and many epochs of cycle slip values from WICSR deviated from the known values. However, the results of the GTCSR were correct, and GTCSR presented a higher success rate than that of WICSR. Furthermore, for the real triple-frequency data, by adding gross errors of 2.5 m on all epoch-difference pseudoranges epoch by epoch, the conventional triple-frequency CSR with the optimized combinations (CTCSR) and the CSD with HMW (HMWCSD) showed many mistakes, where the results of CTCSR and HMWCSD on numerous epochs were inconsistent with the actual situations, but the success rate of GTCSR was significantly higher than those of CTCSR and HMWCSD. In summary, in the condition of the cutoff elevation being larger than 10 degrees, improved performances and higher success rates were achieved from GTCSR under environments of large pseudorange errors and severe ionospheric variations.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improved Cycle Slip Repair with GPS Triple-Frequency Measurements by Minifying the Influences of Ionospheric Variation and Pseudorange Errors

Dang

Yuan

et al. 2021

Remote Sensing

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“…CSR, with a hybrid of MW combination and geometry-free phase, achieves good posterior performance [21]. The ionospheric variation is corrected well from the geometry-free phase by smoothing algorithm [9,22,23]. The accuracy of the MW combination calculation is improved in the smoothing mode as well.…”

Section: Introductionmentioning

confidence: 99%

“…Since the ionosphere is active, it changes dramatically during the magnetic storm [1,[31][32][33]. The ionospheric variation will be amplified by the combination, and will give rise to a striking deviation of more than 0.5 cycles on the cycle slip combination [23,30,34]. Thirdly, the epoch-difference operation is implemented on the combinations, and floating values of the combined cycle slips are obtained and fixed.…”

Section: Introductionmentioning

confidence: 99%

A Cycle Slip Repair Method Against Ionospheric Effects and Observational Noises for BDS Triple-Frequency Undifferenced Phases

Cheng

et al. 2020

Sensors

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The cycle slip detection (CSD) and cycle slip repair (CSR) are easily affected by ionospheric delay and observational noise. Aiming at mitigating the above disadvantage, a new BeiDou navigation satellite system (BDS) triple-frequency CSR method (BTCSR) is proposed for the undifferenced phase. BTCSR learns from the classic triple-frequency CSR (CTCSR), with combinations of phases and pseudoranges in correcting ionospheric delay and optimizing observational noise. Different from CTCSR, though, BTCSR has made the following improvements: (1) An optimal model of calculating cycle slip combination is established, which further takes into account the minimization of the effect of residual ionospheric error after the correction. The calculation of cycle slip combination is obtained with the root mean squared errors (0.0646, 0.1261, 0.1069) of cycles, resulting in CSR success rate of 99.9927%, and the wavelengths (4.8842,3.5738,8.1403) of m. (2) A discriminant function is added to guarantee the CSR correctness. This function utilizes epoch-difference value of the ionosphere-free and geometry-free phase to select the correct cycle slip value, which eliminates the interference of large pseudorange errors in determining the final cycle slip. Consequently, the performances of BTCSR and CTCSR have been compared. For the real BDS pseudorange observation with additional 1.5 m errors, which can cover situations of 99.96% pseudorange noise, results of CTCSR show failure, but results of BTCSR keep correct. Moreover, BTCSR has made the following improvements relative to the geometry-free cycle slip detection method (GFCSD) and Melboune–Wubbena cycle slip combination detection method (MWCSD): (1) During a moderate magnetic storm of level 6, CSR testing, with the BDS monitoring station in a low latitude region, showed that some failures occur in GFCSD because of severe ionospheric variation, but BTCSR could correctly identify and fix cycle slips. (2) For the BDS observation data with an additional 1.5 m error on the actual pseudoranges, MWCSD exhibited failures, but the repair results of BTCSR were correct and reliable. (3) For the special slips of (0,59,62) cycles, and equal slips of (1,1,1) cycles on (B1,B2,B3), that are hard to detect by GFCSD and MWCSD, respectively, BTCSR could repair these correctly. Finally, BTCSR obtains reliable repair results under large pseudorange errors and severe ionospheric variations, and the cut-off elevation larger than 10 degrees is the suggested background.

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“…Although the advantage of these combinations is their high accuracy due to the low carrier observation noise, the integer nature of the combined cycle slips is lacking. Each of these two types of combination can overcome the shortcomings of the other and therefore they are generally employed together [9], [12]- [21].…”

Section: Introductionmentioning

confidence: 99%

An Efficient Cycle-Slip Repair Model With High Success Rate for BDS Triple- Frequency Observations

2019

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An improved cycle-slip repair model is proposed for BDS triple-frequency undifferenced observations. Two extra-wide-lane code-phase combinations and one additional geometry-free (GF) carrierphase combination are employed. To ensure the GF phase combination follows a normal distribution, the residual ionospheric variation of the GF phase combination is corrected in real-time using the previous observation sequence without cycle slip. The integer least squares principle, based on the least-squares ambiguity decorrelation adjustment, is used to solve the fixed value of cycle slip. The corresponding covariance matrix of floating cycle-slip estimations used for construction is updated in real time to improve the fixed efficiency of cycle slip. Moreover, for reliable repair of cycle slip for triple-frequency observations, the critical ratio value between the second-best and best cycle-slip candidates for different residual ionosphere accuracies and different repair success rates are given based on large amounts of simulated data. Lastly, a set of active ionosphere and low-sampling-rate real data was used for evaluation and analysis of the algorithm. Results showed the success rate of cycle-slip repair is 99.997%, even under active ionosphere conditions, with low satellite elevation and low sampling rate. Unfortunately, one cycle-slip group (1, 1, 1) of the C14 satellite was not detected successfully and repaired correctly because of insensitivity to the GF phase combination under bad observation conditions. INDEX TERMS Cycle slip, triple-frequency observations, BDS, integer least squares, ionospheric delay.

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Cycle Slip Detection during High Ionospheric Activities Based on Combined Triple-Frequency GNSS Signals

Cited by 15 publications

References 39 publications

Improved Cycle Slip Repair with GPS Triple-Frequency Measurements by Minifying the Influences of Ionospheric Variation and Pseudorange Errors

Improved Cycle Slip Repair with GPS Triple-Frequency Measurements by Minifying the Influences of Ionospheric Variation and Pseudorange Errors

A Cycle Slip Repair Method Against Ionospheric Effects and Observational Noises for BDS Triple-Frequency Undifferenced Phases

An Efficient Cycle-Slip Repair Model With High Success Rate for BDS Triple- Frequency Observations

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