Ngle of 1 cycle per revolution (CPR) terms changes its sign when
Ngle of 1 cycle per revolution (CPR) terms adjustments its sign when the sign of the angle is changed [9]. This implies that the interaction involving the SRP force and the satellite orbit motion may result in a systematic effect around the orbit determination. Additionally, the impact of the satellite attitude control around the orbit determination also deserves focus. The GPS IIR satellite has maximum yaw rates until the nominal yaw is retrieved through midnight-turn maneuvers [10]. As outlined by yaw angles retrieved by the reverse kinematic PPP method, the GPS IIF satellite might have a disagreement in between the observed yaw plus the nominal yaw at 0 [8,11]. Such yaw or yaw-rate misalignments may well degrade the GNSS measurement accuracy and hinder the orbit determination. The objective of this study was to create a hybrid ECOM model, termed ECOMC, which can be a mixture of ECOM1 and ECOM2, for the SRP impact on GNSS orbit modeling in Ginan computer software. Ginan was created by Geoscience Australia and is an open-source GNSS SR-PSOX/CXCL16 Proteins Biological Activity data-processing computer software. Due to the fact all GPS satellite buses are not completely cubic, ECOM1 might not completely work for the GPS IIR and IIF satellites for reference orbit modeling. In addition, the IIR and IIF have distinct attributes inside the satellite attitude handle. A combination of odd- and even-order CPR terms inside the satellite un path might successfully take care of the disagreement involving the nominal attitude along with the nonnominal attitude. As such, the ECOMC SRP model is proposed for regularly optimizing the reference orbit. In this paper, the ECOM-based models and their parameter estimations are discussed in Sections 2 and three, respectively. In order to realize the dependence between the ECOM-based parameters, an evaluation of parameter correlation is carried out and discussed in Section 4. On top of that, Sections five and six present the orbit quality assessment via the orbit difference with respect to the IGS final item and orbit overlap at day boundaries, respectively. Section 7 assesses the influence in the reference orbit around the estimation of station coordinates applying the PPP strategy. Conclusions are offered in Section 8. two. ECOM-Based Models For the reference orbit modeling, the SRP is the biggest nongravitational force acting on the satellite and is most hard to model. Here, the ECOM-based SRP models are specifically created for any GNSS satellite operated with all the so-called yaw-steering attitude mode [12]. The ECOM-based model is decomposed into three orthogonal axes as eD = rSUN – rSAT , |rSUN – rSAT | eZ eD , |eZ – eD | (1) (2)eY =e =| | e , ||,(1)3 of(2)Remote Sens. 2021, 13,e =,e =e(3)exactly where e is definitely an unit vector linked e = a geocentric satellite position vector r , r (three) with e e , B D Y is the geocentric position vector with the Sun, e points to the Sun direction from the satelwhere ezis FGF-9 Proteins web parallel to the rotation axis of thegeocentric satellite constantly perpendicularSUNthe lite, e is an unit vector connected having a solar panel and is position vector rSAT , r to will be the vector, and the e vector in the Sun, ethe righthand rule of e and e , as shown in e geocentric position vector is given by D points to the Sun direction in the satellite, eY is parallel tothat the Y-axis in thethe solar panelmodel (in black) is usually aligned with Figure 1. Note the rotation axis of ECOM-based and is usually perpendicular for the eD vector, and satellite attitude (in red). The so-called Sun-fixed frame as constructed by u that inside the the eB vect.
