Reliable Integer Ambiguity Resolution: Multi-Frequency Code Carrier Linear Combinations and Statistical A Priori Knowledge of Attitude

Abstract

This paper provides two methods to improve the reliability of carrier phase integer ambiguity resolution: The first one is a group of multi‐frequency linear combinations that include both code and carrier phase measurements, and allow an arbitrary scaling of the geometry, an arbitrary scaling of the ionospheric delay, and any preferred wavelength. The maximization of the ambiguity discrimination results in combinations with a wavelength of several meters and a noise level of a few centimeters. These combinations could be beneficial for both Real‐Time Kinematics (RTK) and Precise Point Positioning (PPP). The second method incorporates some statistical a priori knowledge of attitude into the actual fixing. The a priori knowledge includes the length and direction of the baseline between two receivers and is given either as a uniform or Gaussian distribution. It enables a substantial reduction of the search space volume but also ensures a large robustness over errors in the a priori information. Both methods improve the accuracy of the float solution, which motivates a simple rounding for ambiguity fixing. A method is described, which enables an efficient computation of its success rate with a few integral transformations. Copyright © 2012 Institute of Navigation.

Improving the Triple-Carrier Ambiguity Resolution with a New Ionosphere-Free and Variance-Restricted Method

“…Therefore, the new WL combination method can sufficiently restrict the combined observation noise under ionosphere-free combination, which is able to obtain a better ambiguity resolution performance. Because of the presence of geometry terms, the rank deficiency issue exists for (5). Therefore, additional ionosphere-free combination should be constructed.…”

“…The triple-carrier ambiguity resolution (TCAR) method proposed by the authors of [2,3] is one of the widely-used approaches for resolving the triple-frequency ambiguity in a short baseline case so that the ionospheric error can be neglected. When the ionospheric bias cannot be neglected, especially in medium and long baseline cases, much research has also been done to improve its performance [4][5][6][7]. A common conclusion is that both the ionospheric bias and combined observation noise are two crucial factors for the reliability of TCAR [4,8].…”

“…These studies aim at suppressing the effect of ionospheric bias and combined observation noise [4,5,8,13,14]. The coefficients can be determined based on different categories to suppress these two kinds of observation errors.…”

“…Therefore, the reliability of the ionosphere-estimated method has its limitations. In contrast, the observation combination method has enormous potential in mitigating the effect of ionospheric bias so that the reliability of TCAR can be improved [5,8,13]. Typically, the ionosphere-free combination is usually used for eliminating the effect of ionospheric bias on TCAR.…”

Triple-Frequency Code-Phase Combination Determination: A Comparison with the Hatch-Melbourne-Wübbena Combination Using BDS Signals

“…Henkel and Günther [23] recommended a group of code-phase combinations with a wavelength of several meters and a noise level of a few centimeters, to maximize the ambiguity discrimination and ensure the reliability. Wang and Rothacher [24] presented a simplified method to minimize the noise level for the triple-frequency GF and ionosphere-free (GIF) linear combinations with both code and carrier phase measurements.…”