scholarly journals DETECTING CYCLE SLIPS IN CARRIER-PHASE MEASURMENTS OF NAVIGATION RECEIVER WITH HIGH STABLE REFERENCE GENERATORS

2021 ◽  
Author(s):  
Aleksandr Pustoshilov
Keyword(s):  
Carrier Phase ◽  
Single Frequency ◽  
Simple Method ◽  
Phase Measurements ◽  
Frequency Measurements ◽  
Cycle Slips ◽  
High Degree

The paper shows a simple method for detecting cycle slips in the carrier-phase measurements (including single frequency measurements) of navigation receivers with highly stable (hydrogen) reference oscillators by using approximation by high-degree polynomials.

scholarly journals Detecting Cycle Slips in Carrier-Phase Measurements of Single Frequency Navigation Receivers with Different Instabilities of Reference Oscillators

2021 ◽  
Vol 5 (2) ◽  
pp. 144-161
Author(s):  
A. S. Pustoshilov ◽  
◽  
S. P. Tsarev ◽  
Keyword(s):  
Carrier Phase ◽  
Single Frequency ◽  
Navigation Systems ◽  
Noise Component ◽  
Phase Measurements ◽  
Additional Information ◽  
Cycle Slips ◽  
Reference Oscillator ◽  
The Difference ◽  
Polynomial Filtering

The use of carrier-phase measurements significantly increases the accuracy of solutions when using the measurements of navigation receivers. One of the problems in carrier-phase measurements is discontinuities (cycle slips) in the measurements. The existing algorithms of detection and compensation of cycle slips in carrier-phase measurements of a singlefrequency navigation receiver either require additional information (for example, Doppler measurements), or operate only in differential mode, or can only detect large cycle slips. The purpose of the research is the development of algorithms for detecting small cycle slips in carrier-phase measurements of single-frequency receivers without using additional information. We use methods of filtering of the trend in the carrier-phase measurements using polynomial or adaptive bases, as well as modified sparse recovery algorithms to estimate cycle slips in the difference between code and carrier-phase measurements. The algorithm which is used to search cycle slips in carrier-phase measurements depends on the quality of the reference oscillator of the navigation receiver. For receivers with high-stability reference oscillators (e.g. active hydrogen maser), one can use polynomial filtering of the trend, the filtering result directly detects discontinuities in carrier-phase measurements with a probability close to unity. For navigation receivers with low-stability reference oscillators (quartz reference oscillators), a modified algorithm for minimization of the total variation with filtering of the trend applied to the difference between the code and carrier-phase single-frequency measurements detects discontinuities in 1 cycle slip against the background of the noise component of comparable magnitude with a probability of 0.8. The results may be applied in navigation systems with single-frequency receivers with low stability reference oscillators, as well as in a posteriori processing of receivers’ measurements to correct carrier-phase measurements on the preprocessing stage.

scholarly journals Improving DGNSS Performance through the Use of Network RTK Corrections

2021 ◽  
Vol 13 (9) ◽  
pp. 1621
Author(s):  
Duojie Weng ◽  
Shengyue Ji ◽  
Yangwei Lu ◽  
Wu Chen ◽  
Zhihua Li
Keyword(s):  
Carrier Phase ◽  
Local Area ◽  
Satellite System ◽  
High Accuracy ◽  
Single Frequency ◽  
Baseline Length ◽  
Low Latitude ◽  
Phase Measurements ◽  
Network Rtk ◽  
Global Navigation Satellite

The differential global navigation satellite system (DGNSS) is an enhancement system that is widely used to improve the accuracy of single-frequency receivers. However, distance-dependent errors are not considered in conventional DGNSS, and DGNSS accuracy decreases when baseline length increases. In network real-time kinematic (RTK) positioning, distance-dependent errors are accurately modelled to enable ambiguity resolution on the user side, and standard Radio Technical Commission for Maritime Services (RTCM) formats have also been developed to describe the spatial characteristics of distance-dependent errors. However, the network RTK service was mainly developed for carrier-phase measurements on professional user receivers. The purpose of this study was to modify the local-area DGNSS through the use of network RTK corrections. Distance-dependent errors can be reduced, and accuracy for a longer baseline length can be improved. The results in the low-latitude areas showed that the accuracy of the modified DGNSS could be improved by more than 50% for a 17.9 km baseline during solar active years. The method in this paper extends the use of available network RTK corrections with high accuracy to normal local-area DGNSS applications.

scholarly journals Robust INS/SFPPP-BDS tightly coupled navigation algorithm with adaptive cycle slip compensation model

2019 ◽  
Vol 13 ◽  
pp. 174830181983304
Author(s):  
Hangshuai Ma ◽  
Rong Wang ◽  
Zhi Xiong ◽  
Jianye Liu ◽  
Chuanyi Li
Keyword(s):  
Navigation System ◽  
Carrier Phase ◽  
Low Cost ◽  
Integrated System ◽  
Single Frequency ◽  
Cycle Slip ◽  
Phase Measurements ◽  
Satellite Navigation System ◽  
Tightly Coupled ◽  
Robust Adaptive

The application of Beidou Satellite Navigation System (BDS) is developing rapidly. To satisfy the increasing demand for positioning performance, single-frequency precise point positioning (SFPPP) has been a focus in recent years. By introducing the SFPPP technique into the INS/BDS integrated system, higher navigation accuracy can be obtained. Cycle slip, which is caused by signal blockage during the measurement of the carrier phase, is a challenge for SFPPP application. In the INS/SFPPP-BDS integrated system, cycle slip can cause serious bias in BDS carrier phase measurements. In this paper, a new INS/SFBDS-PPP tightly coupled navigation system and a robust adaptive filtering method are proposed. Using a low-cost single-frequency receiver integrated with INS, an observation model was built based on the pseudo range and carrier phase by PPP preprocessing. The cycle slip was introduced into the state vector to improve the estimation precision. The test statistics, comprising the innovation and its covariance, were used to estimate the time at which cycle slip occurred and its amplitude to compensate for its effect on the observation. Finally, the proposed system model and algorithm are validated by simulation.

Effective Cycle Slip Detection and Identification for High Precision GPS/INS Integrated Systems

2003 ◽  
Vol 56 (3) ◽  
pp. 475-486 ◽  
Author(s):  
Hung-Kyu Lee ◽  
Jinling Wang ◽  
Chris Rizos
Keyword(s):  
Carrier Phase ◽  
Statistical Technique ◽  
Cycle Slip ◽  
Cusum Test ◽  
Mean Values ◽  
Phase Measurements ◽  
Additional Information ◽  
Cycle Slips ◽  
Detection And Identification ◽  
Cycle Slip Detection

To ensure high accuracy results from an integrated GPS/INS system, the carrier phase observables have to be used to update the filter's states. As a prerequisite the integer ambiguities must be resolved before using carrier phase measurements. However, a cycle slip that remains undetected (and uncorrected) will significantly degrade the filter's performance. In this paper, an algorithm that can effectively detect and identify any type of cycle slip is presented. The algorithm uses additional information provided by the INS, and applies a statistical technique known as the cumulative-sum (CUSUM) test. In this approach, cycle slip decision values can be computed from the INS-predicted position (due to the fact that its short-term accuracy is very high), and the CUSUM test used to detect cycle slips (as it is very sensitive to abrupt changes of mean values). Test results are presented to demonstrate the effectiveness of the proposed algorithm.

scholarly journals A Cycle Slip Detection Framework for Reliable Single Frequency RTK Positioning

Sensors ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 304 ◽  
Author(s):  
Salma Zainab Farooq ◽  
Dongkai Yang ◽  
Echoda Ngbede Joshua Ada
Keyword(s):  
Carrier Phase ◽  
Measurement Errors ◽  
Statistical Tests ◽  
Measurement Data ◽  
Single Frequency ◽  
Adjustment Process ◽  
Common Source ◽  
Detection Scheme ◽  
Cycle Slips ◽  
Phase Cycle

Single frequency real-time kinematic (RTK) positioning is expected to be the leading implementation platform for a variety of emerging GNSS mass-market applications. During RTK positioning, the most common source of measurement errors is carrier-phase cycle slips (CS). The presence of CS in carrier-phase measurements is tested by a CS detection technique and correspondingly taken care of. While using CS prone measurement data, positioning reliability is an area of concern for RTK users. Reliability can be linked with the CS detection scheme through a least squares (LS) adjustment process. This paper proposes a CS detection framework for reliable RTK positioning using single-frequency GNSS receivers. The scheme uses double differenced measurements for CS detection via LS adjustment using a detection, identification, and adaptation approach. For reliable positioning, the procedure to link the detection and identification stages is described. Through tests conducted on kinematic data, internal and external reliability are theoretically determined by calculating minimal detectable bias (MDB) and marginally detectable errors, respectively. After introducing CS, the actual values of MDB are found to be four cycles, which are higher than the theoretically obtained values of one and two cycles. Although CS detection for reliable positioning is implemented for single-frequency RTK users, the proposed procedure is generic and can be used whenever CS are detected through statistical tests during LS adjustment.

scholarly journals Improvement of Carrier Phase Tracking Based on a Joint Vector Architecture

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Shaohua Chen ◽  
Yang Gao
Keyword(s):  
Carrier Phase ◽  
Satellite System ◽  
Phase Lock Loop ◽  
Tracking Loop ◽  
Phase Measurements ◽  
Phase Tracking ◽  
Cycle Slips ◽  
Carrier Phase Tracking ◽  
The Individual ◽  
Global Navigation Satellite

Carrier phase measurements are essential to high precision positioning. Usually, the carrier phase measurements are generated from the phase lock loop in a conventional Global Navigation Satellite System (GNSS) receiver. However there is a dilemma problem to the design of the loop parameters in a conventional tracking loop. To address this problem and improve the carrier phase tracking sensitivity, a carrier phase tracking method based on a joint vector architecture is proposed. The joint vector architecture contains a common loop based on extended Kalman filter to track the common dynamics of the different channels and the individual loops for each channel to track the satellite specific dynamics. The transfer function model of the proposed architecture is derived. The proposed method and the conventional scalar carrier phase tracking are tested with a high quality simulator. The test results indicate that carrier phase measurements of satellites start to show cycle slips using the proposed method when carrier noise ratio is equal to and below 15 dB-Hz instead of 21 dB-Hz with using the conventional phase tracking loop. Since the joint vector based tracking loops jointly process the signals of all available satellites, the potential interchannel influence between different satellites is also investigated.

scholarly journals Performance Comparison among Multi-GNSS Single Frequency Precise Point Positioning Techniques

2019 ◽  
Vol 18 (32) ◽  
pp. 80-99
Author(s):  
Anna Innac ◽  
Antonio Angrisano ◽  
Salvatore Gaglione ◽  
Mario Vultaggio ◽  
Nicola Crocetto
Keyword(s):  
Carrier Phase ◽  
Precise Point Positioning ◽  
A Priori ◽  
Performance Comparison ◽  
Single Frequency ◽  
Integer Number ◽  
Phase Measurements ◽  
Processing Strategies ◽  
Wide Range ◽  
Point Positioning

Precise Point Positioning (PPP) is a technique able to compute high accuracy positioning anywhere using a single GNSS receiver and without the need for corrections from reference stations. A wide range of possible PPP algorithms, using different correction models and processing strategies, exist for both post-processing and real-time applications. PPP relies on accurate satellite and clock data, with the use of precise carrier-phase measurements. Single Frequency-PPP (SF-PPP) is currently under investigation by the scientific community, owing to its cheap implementation with respect to classical differential positioning and multi-frequency un-differenced techniques. Unfortunately, the carrier-phase observable is ambiguous by an a priori unknown integer number of cycles, called ambiguity, which is difficult to resolve with SF receivers. The aim of this paper was to study the opportunity provided by the use of a multi-GNSS constellation applied to two widespread SF-PPP models, based on different carrier-phase and code observable combinations. The algorithms were tested using static data collection carried out in an open-sky scenario. The results show decimeter level accuracy on the horizontal and vertical components of the position.

scholarly journals Evaluation of a Low Cost Hand Held Unit with GNSS Raw Data Capability and Comparison with an Android Smartphone

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4185 ◽  
Author(s):  
Gérard Lachapelle ◽  
Paul Gratton ◽  
Jamie Horrelt ◽  
Erica Lemieux ◽  
Ali Broumandan
Keyword(s):  
Carrier Phase ◽  
Low Cost ◽  
High Sensitivity ◽  
Measurement Noise ◽  
Single Frequency ◽  
Raw Data ◽  
Phase Measurements ◽  
Position Accuracy ◽  
Wide Range ◽  
Free Position

A newly available portable unit with GNSS raw data recording capability is assessed to determine static and kinematic position accuracy in various environments. This unit is the GPSMap 66, introduced by Garmin in early September. It is all-weather and robust for field use, and comes with a helix antenna. The high sensitivity chipset is capable of acquiring and tracking signals in highly attenuated environments. It can track single frequency GPS, GPS + GLONASS or GPS + Galileo and record code, Doppler and carrier phase data every second in the RINEX format. The evaluation presented herein focusses on GPS and Galileo. Static and kinematic test results obtained under a wide range of realistic field conditions are reported. Differential GNSS methods and Precise Point Positioning (PPP) are used to assess absolute position accuracy in ITRF coordinates, which is sufficiently close to the GPS and Galileo reference frame for the current purpose. Under low multipath conditions, measurements are found to be sufficiently accurate to provide single epoch, bias free position accuracy of a few metres. Accuracy is a function of signal attenuation and multipath conditions. The use of an external geodetic antenna significantly reduces measurement noise and multipath in high multipath environments. Carrier phase measurements, available more or less continuously under open sky conditions, significantly improve performance in differential mode. Accuracy in vehicular mode using code and carrier phase differential RTK solution is at the level of a few to several dm. Tests were conducted in parallel with a Huawei P10 Android 8.0 smartphone. The code measurement noise of this unit was found to be significantly higher than that of the GPSMap 66, a major reason being its lower performance PIFA antenna; carrier phase was only available for short time intervals, significantly degrading differential position accuracy performance.

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