In-flight performance analysis of the navigation augmentation payload on LEO communication satellite: a preliminary study on WT01 mission

Figures & data

Figure 1. The WT01 twin satellites.

Figure 2. The navigation augmentation payload (left) and ground receiver (right) of the WT01 twin satellites.

Figure 3. Schematic diagram of WT01 satellite data collection.

Table 1. Specific data collection period of the WT01A/B downlink navigation observation

Arc	Date	Tracking time	Tracking satellite
1	2019–07-06	14:12:29–14:17:24	WT01-B
2	2019–07-07	14:10:41–14:16:35	WT01-B
3	2019–07-11	12:26:41–12:32:23	WT01-B
4	2019–07-12	12:25:47–12:31:47	WT01-A/B
5	2019–07-13	12:25:17–12:30:51	WT01-A/B

Table 2. Dynamic POD model and strategy for WT01 mission

Model	Description
Mean Earth gravity	GGM03C (120 × 120) (Tapley et al. 2007)
N-body	JPL DE 421 (Folkner, Williams, and Boggs 2009)
Solid earth tides	IERS 2010 conventions (Petit and Luzum 2010)
Ocean tides	FES2004 (Lyard et al. 2006)
Pole tide	IERS 2010 conventions (Petit and Luzum 2010)
Relativity	IERS 2010 conventions (Petit and Luzum 2010)
Solar radiation pressure	Box-wing (Rim 1992), one Cr per arc
Atmospheric drag	Density Temperature Model (DTM) (Barlier et al. 1978), one Cd per 3-hour
Empirical acceleration	Empirical accelerations in R direction are switched off; piecewise linear and cosine parameters are estimated every 3-hour in T and N directions
Precession and nutation	IERS 2010 conventions (Petit and Luzum 2010)
Earth Orientation Parameters (EOP)	IERS C04 (http://hpiers.obspm.fr/iers/eop/eopc04/)
GNSS satellite antenna PCO/PCV	IGS ATX model igs14.atx (https://lists.igs.org/pipermail/igsmail/2016/001233.html)

Figure 4. The visible GPS satellite number (top) and PDOP (bottom) of the WT01 twin satellites.

Figure 5. The visible BDS satellite number (top) and PDOP (bottom) of the WT01 twin satellites.

Figure 6. The statistics of the tracked satellites per epoch for BDS B1, B2 and GPS L1, L2 observation of WT01-A spaceborne GNSS receiver.

Figure 7. The statistics of the tracked satellites per epoch for BDS B1, B2 and GPS L1, L2 observation of WT01-B spaceborne GNSS receiver.

Figure 8. The multipath errors for GPS L1 (left) and L2 (right) of the WT01-A (top) and WT01-B (bottom) satellites.

Figure 9. The multipath errors for BDS B1 (left) and B2 (right) of the WT01-A (top) and WT01-B (bottom) satellites.

Table 3. The mean multipath errors for on-board GPS and BDS observation (unit: m)

Satellite	GPS		BDS
	L1	L2	B1	B2
WT01-A	0.51	0.73	0.63	0.57
WT01-B	0.57	0.74	0.66	0.59

Figure 10. Orbit overlap zone diagram.

Figure 11. Error bar of the orbit overlapping precision in R, T, N, and 3D direction of the WT01-B satellite.

Figure 12. Code and phase residuals of WT01-B satellite short-arc POD.

Figure 13. The multipath errors for Z1 (left) and Z2 (right) navigation signals of WT01-A (top) and WT01-B (bottom) satellites.

Figure 14. The average multipath errors of Z1, Z2, L1, L2, B1, and B2 frequencies.

Table 4. The multipath errors for WT01-A/B, GPS, and BDS downlink navigation observation (unit: m)

Arc	WT01-A		WT01-B		GPS		BDS
	Z1	Z2	Z1	Z2	L1	L2	B1	B2
1	-	-	0.85	0.79	0.70	0.64	0.72	0.63
2	-	-	0.77	0.86	0.65	0.66	0.63	0.59
3	-	-	0.79	0.71	0.71	0.51	0.67	0.61
4	0.79	0.77	0.74	0.75	0.60	0.30	0.51	0.46
5	0.88	0.90	0.85	0.84	0.64	0.49	0.74	0.63

Figure 15. The C/N₀ of WT01-A (left) and WT01-B (right) navigation signals on 13 July 2019.

Figure 16. The C/N₀ of GPS L1 (green), L2 (black) and BDS B1 (cyan), B2 (magenta) navigation signals on 13 July 2019.

Table 5. The C/N₀ range of WT01-A/B, GPS, and BDS downlink navigation observation (unit: dB/Hz)

Arc	WT01-A		WT01-B		GPS		BDS
	Z1	Z2	Z1	Z2	L1	L2	B1	B2
1	-	-	38.7–55.8	38.7–53.0	30.4–49.6	19.4–46.0	32.3–47.3	39.2–49.3
2	-	-	38.1–58.5	39.3–56.9	34.5–49.1	18.6–46.1	31.8–47.3	39.9–50.0
3	-	-	38.9–53.8	38.5–53.1	28.5–54.5	22.4–47.8	37.1–47.0	39.2–49.3
4	40.3–51.5	42.6–52.2	36.7–52.9	37.3–52.3	38.1–49.4	25.5–46.6	32.8–46.6	37.5–47.3
5	42.8–59.8	42.5–60.0	37.3–55.0	37.0–57.5	35.6–52.9	25.1–47.4	36.1–48.2	40.2 –49.5

Tapley, B., J. Ries, S. Bettadpur, D. Chambers, M. Cheng, F. Condi, and S. Poole. 2007. “The GGM03 Mean Earth Gravity Model from GRACE.” In AGU Fall Meeting, G42A–03.

 Google Scholar

Folkner, W.M., J.G. Williams, and D.H. Boggs. 2009. “The Planetary and Lunar Ephemeris DE 421.” The Interplanetary Network Progress Report 42: 178.

 Google Scholar

Petit, G., and B. Luzum. 2010. “IERS Conventions 2010.” IERS Technical Note. Germany.

 Google Scholar

Lyard, F., F. Lefevre, T. Letellier, and O. Francis. 2006. “Modelling the Global Ocean Tides: Moden Insights from FES2004.” Ocean Dynamics 56: 394–415. doi:https://doi.org/10.1007/s10236-006-0086-x.

 Web of Science ®Google Scholar

Rim, H. 1992. “TOPEX Orbit Determination Using GPS Tracking System.” Ph.D. thesis, Texas University, Austin, USA.

 Google Scholar

Barlier, F., C. Berger, J.L. Falin, G. Kockarts, and G. Thuillier. 1978. “A Thermospheric Model Based on Satellite Drag Data.” Annales de Geophysique 34: 9–24.

 Google Scholar

Data availability statement

The data that support the findings of this study are available from the corresponding author, upon reasonable request.