Reduced-order adaptive Kalman filtering for dual-frequency navigation with carrier phase

2011 ◽  
Author(s):  
Chenxi Lu ◽  
Yunhua Tan ◽  
Lezhu Zhou
Keyword(s):  
Kalman Filtering ◽  
Carrier Phase ◽  
Dual Frequency ◽  
Reduced Order

scholarly journals Characterization of Carrier Phase-Based Positioning in Real-World Jamming Conditions

2021 ◽  
Vol 13 (14) ◽  
pp. 2680
Author(s):  
Søren Skaarup Larsen ◽  
Anna B. O. Jensen ◽  
Daniel H. Olesen
Keyword(s):  
Real World ◽  
Carrier Phase ◽  
Reference Station ◽  
Baseline Length ◽  
Dual Frequency ◽  
Positioning Accuracy ◽  
The Impact ◽  
Single Versus ◽  
Selection Of

GNSS signals arriving at receivers at the surface of the Earth are weak and easily susceptible to interference and jamming. In this paper, the impact of jamming on the reference station in carrier phase-based relative baseline solutions is examined. Several scenarios are investigated in order to assess the robustness of carrier phase-based positioning towards jamming. Among others, these scenarios include a varying baseline length, the use of single- versus dual-frequency observations, and the inclusion of the Galileo and GLONASS constellations to a GPS only solution. The investigations are based on observations recorded at physical reference stations in the Danish TAPAS network during actual jamming incidents, in order to realistically evaluate the impact of real-world jamming on carrier phase-based positioning accuracy. The analyses performed show that, while there are benefits of using observations from several frequencies and constellations in positioning solutions, special care must be taken in solution processing. The selection of which GNSS constellations and observations to include, as well as when they are included, is essential, as blindly adding more jamming-affected observations may lead to worse positioning accuracy.

scholarly journals Real-time GNSS precise point positioning for low-cost smart devices

GPS Solutions ◽  
2021 ◽  
Vol 25 (2) ◽  
Author(s):  
Liang Wang ◽  
Zishen Li ◽  
Ningbo Wang ◽  
Zhiyu Wang
Keyword(s):  
Carrier Phase ◽  
Measurement Errors ◽  
Precise Point Positioning ◽  
Low Cost ◽  
Smart Devices ◽  
Dual Frequency ◽  
Static Mode ◽  
Phase Measurements ◽  
Positioning Errors ◽  
Point Positioning

AbstractGlobal Navigation Satellite System raw measurements from Android smart devices make accurate positioning possible with advanced techniques, e.g., precise point positioning (PPP). To achieve the sub-meter-level positioning accuracy with low-cost smart devices, the PPP algorithm developed for geodetic receivers is adapted and an approach named Smart-PPP is proposed in this contribution. In Smart-PPP, the uncombined PPP model is applied for the unified processing of single- and dual-frequency measurements from tracked satellites. The receiver clock terms are parameterized independently for the code and carrier phase measurements of each tracking signal for handling the inconsistency between the code and carrier phases measured by smart devices. The ionospheric pseudo-observations are adopted to provide absolute constraints on the estimation of slant ionospheric delays and to strengthen the uncombined PPP model. A modified stochastic model is employed to weight code and carrier phase measurements by considering the high correlation between the measurement errors and the signal strengths for smart devices. Additionally, an application software based on the Android platform is developed for realizing Smart-PPP in smart devices. The positioning performance of Smart-PPP is validated in both static and kinematic cases. Results show that the positioning errors of Smart-PPP solutions can converge to below 1.0 m within a few minutes in static mode and the converged solutions can achieve an accuracy of about 0.2 m of root mean square (RMS) both for the east, north and up components. For the kinematic test, the RMS values of Smart-PPP positioning errors are 0.65, 0.54 and 1.09 m in the east, north and up components, respectively. Static and kinematic tests both show that the Smart-PPP solutions outperform the internal results provided by the experimental smart devices.

Precise carrier phase altimetry over lakes using dual-frequency reflected signals of the Global Navigation Satellite Systems (GNSS)

2021 ◽  
Author(s):  
Estel Cardellach ◽  
Weiqiang Li ◽  
Dallas Masters ◽  
Takayuki Yuasa ◽  
Franck Borde ◽  
...  
Keyword(s):  
Sea Ice ◽  
Carrier Phase ◽  
Radio Occultation ◽  
Global Navigation Satellite Systems ◽  
Data Sets ◽  
Dual Frequency ◽  
Effective Wavelength ◽  
Raw Data ◽  
Satellite Systems ◽  
Global Navigation Satellite

<p>Recently, different studies have shown evidence of signals transmitted by the Global Navigation Satellite Systems (GNSS), coherently reflected over some parts of the ocean, and received from cubesats. In particular, strong coherent scattering has been reported in regions with low water surface roughness as those near continental masses and in atolls. Over open ocean, few coherent signals were reported to be found, although the data sets were somewhat limited and certainly not exhaustive. The level of coherence in reflected GNSS signals depends on the roughness of the  surface (i.e. significant wave height and small scale ripples and waves induced by the wind), the viewing geometry (i.e. incidence angle, or equivalently, elevation angle of the GNSS satellite as seen from the point of reflection), propagation effects (namely ionospheric disturbances) and on the frequency (i.e. particular GNSS band, like L1/E1, L2 or L5/E5). These coherent measurements over ocean follow earlier evidence of coherent GNSS reflections over sea ice which date back to 2005, the time of UK-DMC mission. More recently, Sea Ice Thickness (SIT) retrievals have also been carried out with this technique, at an accuracy comparable to that of SMOS.</p><p>All the observations referred so far were done at a single frequency, L1/E1. So, there is an interest to explore the coherence at the other main GNSS bands, i.e. L2 and L5/E5 as well as to the widelane combinations between them (linear combinations of carrier-phase measurements, of longer effective wavelength). Spire Global radio occultation cubesats work at L1 and L2 frequency bands, and therefore provide unique dual-frequency raw data sets of reflected signals over open ocean, sea ice and inland water bodies. With these, it is possible to study the coherence of these targets at each of the bands and at their widelane combination, as well as the performance of altimetric retrievals at grazing angles of observation (very slant geometries, which facilitate coherence properties of the scattering). The dual-frequency observations can correct the ionospheric effects, and their widelane combinations, of longer effective wavelength, might expand the conditions for coherence. The fact that this new approach is fully compatible with small GNSS radio occultation payloads and missions, might represent a low cost source of precise altimetry to complement larger dedicated missions.</p><p>An ESA research study involving Spire Global and IEEC aims at studying this new potential altimetric technique. Raw data acquisitions from limb-looking antennas of Spire’s cubesat constellation were selected to be geographically and time collocated with ESA Sentinel 3A and 3B passes in order to compare the results of coherence and altimetry. For this study, the raw data at two frequencies, acquired at 6.2 Mbps, are shifted to intermediate frequencies and downloaded to the ground without any further processing. In-house software receivers are then applied to generate the reflected echoes or waveforms, and to track the phase of the carrier signals. Precise altimetry (a few cm in 20 ms integration) is then possible from these observables. The results of this activity will be shown, focusing on altimetric retrievals over large lakes.</p>

scholarly journals A Dual Frequency Carrier Phase Error Difference Checking Algorithm for the GNSS Compass

Sensors ◽  
2016 ◽  
Vol 16 (12) ◽  
pp. 1988 ◽  
Author(s):  
Shuo Liu ◽  
Lei Zhang ◽  
Jian Li
Keyword(s):  
Carrier Phase ◽  
Phase Error ◽  
Dual Frequency ◽  
Carrier Phase Error

Real-time carrier phase multipath detection based on dual-frequency C/N0 data

GPS Solutions ◽  
2018 ◽  
Vol 23 (1) ◽  
Author(s):  
Zhetao Zhang ◽  
Bofeng Li ◽  
Yang Gao ◽  
Yunzhong Shen
Keyword(s):  
Real Time ◽  
Carrier Phase ◽  
Dual Frequency ◽  
Multipath Detection

scholarly journals Integration and Simulations of INS/GNSS System using the Approach of Carrier Phase Measurements

2015 ◽  
Vol 4 (4) ◽  
pp. 243
Author(s):  
Khan Badshah ◽  
Qin Yongyuan
Keyword(s):  
Kalman Filtering ◽  
Carrier Phase ◽  
Closed Loop ◽  
Position Estimation ◽  
Integrated System ◽  
Integer Ambiguity ◽  
Font Size ◽  
Phase Measurements ◽  
Simulation Results ◽  
Lever Arm Effect

<p class="MsoNormal" style="margin-top: 12.0pt; margin-right: 0in; margin-bottom: 6.0pt; margin-left: 0in; text-align: justify;"><em><span style="font-size: 9.0pt; font-family: &quot;Arial&quot;,sans-serif; mso-ascii-theme-font: minor-bidi; mso-hansi-theme-font: minor-bidi; mso-bidi-theme-font: minor-bidi;" lang="EN-GB">This paper discusses the techniques of attitude, velocity ad position estimation from GNSS carrier phase measurements, and investigates the performance of the lower precision MEMS-based INS/GNSS system based on carrier phase measurements. Double differenced carrier phase measurements provide more accurate velocity and position estimation compared to code and Doppler measurements. However, integer ambiguity is required to be removed for precise positioning. Multiples<span style="color: red;"> </span>antennae approach is used to derive the attitude information from carrier phase measurements in order to control the large initial misalignment angles for initialization of the integration process or to utilize during benign dynamics. Lever arm effect is considered to compensate for the separation of GNSS antenna and IMU location. The derived three GNSS observables are used to correct the INS through optimal Kalman filtering in a closed loop. Simulation results indicates the effectiveness of the integrated system for airborne as well as for land navigation vehicles</span></em><span lang="EN-GB">. </span></p><div id="_mcePaste" class="mcePaste" style="position: absolute; left: -10000px; top: 0px; width: 1px; height: 1px; overflow: hidden;"><p class="MsoNormal" style="margin-top: 12.0pt; margin-right: 0in; margin-bottom: 6.0pt; margin-left: 0in; text-align: justify;"><em><span style="font-size: 9.0pt; font-family: &quot;Arial&quot;,sans-serif; mso-ascii-theme-font: minor-bidi; mso-hansi-theme-font: minor-bidi; mso-bidi-theme-font: minor-bidi;" lang="EN-GB">This paper discusses the techniques of attitude, velocity ad position estimation from GNSS carrier phase measurements, and investigates the performance of the lower precision MEMS based INS/GNSS system based on carrier phase measurements. Double differenced carrier phase measurements provide more accurate velocity and position estimation compared to code and Doppler measurements. However, integer ambiguity is required to be removed for precise positioning. Multiples<span style="color: red;"> </span>antennae approach is used to derive the attitude information from carrier phase measurements in order to control the large initial misalignment angles for initialization of the integration process or to utilize during benign dynamics. Lever arm effect is considered to compensate for the separation of GNSS antenna and IMU location. The derived three GNSS observables are used to correct the INS through optimal Kalman filtering in a closed loop. Simulation results indicates the effectiveness of the integrated system for airborne as well as for land navigation vehicles</span></em><span lang="EN-GB">. </span></p></div>

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