The Stability Analysis of GNSS Satellite DCB

Transcription

1 The Stability Analysis of GNSS Satellite DCB Shuli Song, Junchen Xue, Zhengbiao Zou ShangHai Astronomical Observatory Sydeny

2 Outline l Introduction l GPS DCB analysis l GLONASS DCB analysis l BDS DCB analysis l GALILEO DCB analysis

3 1. Introduction The instrumental differential code bias(dcb) is one of the important parameters for GNSS navigation, positioning and time service, and also the main source error of TEC estimation. How stable these DCBs are? How often we need to reestimate their values? How about the Galileo/BDS DCBs? Can we use monthly mean values for BDS/Galileo postprocessing as GPS/GLONASS?... Here,the DCB series of GNSS main frequency from CODE and SHAO igmas Analysis Center are analyzed.

4 2.GPS P1P2 DCB Analysis Original daily GPS satellite DCB from 1998 to 213 from CODE DCB/ns CODE DCB PRN6 PRN15 PRN3 DCB/ns BLOCK IIR-M: PRN DCB PRN5 PRN7 PRN12 PRN15 PRN17 PRN29 PRN The DCB series are not so smooth with many jumps. What s that? Why the variations are large before 22?

5 32 number of GPS satellites.1 DCB difference between doy 155 and 156 of 21 before remove bias after remove bias difference/ns PRN The GPS satellite numbers in ION/DCB calculation change at all times. There re artificial biases in DCB series due to the variation of satellite number.so,the biases have to be removed before the stability analysis.

6 DCB/ns BLOCK IIA: PRN DCB PRN3 PRN4 PRN6 PRN8 PRN9 PRN1 PRN13 PRN DCB/ns BLOCK IIA: PRN DCB(after remove bias) PRN3 PRN4 PRN6 PRN8 PRN9 PRN1 PRN13 PRN

7 stable. Long-term Stability of GPS P1P2 DCB Linear trends of all GPS satellites during Most GPS DCB longterm trend are less than 1ps.Block IIF and Block IIA DCBs are more

8 Mean monthly stability of GPS satellite DCBs Block II satellites Block IIA satellites during monthly stability/ns Block IIA satellites during Block IIR-M satellites Block IIR-A satellites Block IIF and IIR-B satellites PRN PRN Block II and Block IIA(before 22) with mean monthly stability about 1ps,Block IIA(after 22) and other Blocks with less than 5ps.

9 Monthly variations of Block IIA satellite DCBs monthly stability/ns PRN PRN PRN PRN PRN4 PRN8 PRN1 PRN Most are less than 1 ps.

10 monthly stability/ns Monthly stability of satellites DCB and solar activity SUNSPOT PRN3 PRN4 PRN6 PRN8 PRN9 PRN1 PRN13 PRN26 sunspot Variation of annual average of monthly stability of Block IIA satellite DCBs with ly sunspot, though the amplitude is not two large.

11 Short-term stability of GPS P1P2 DCB Daily variation 1 week 2 weeks.. 8 weeks variation Dif between 4weeks and week : no difference for Block II, but large than other Blocks.Others: changed in 8~21ps with the statistic interval expand

12 3.GLONASS DCB Analysis 25 satellite numbers variation GLONASS 卫星数变化情况

13 Before bias remove After bias remove GLONASS 卫星 DCB GLONASS 卫星 DCB DCB/ns 5-5 R2 R3 R4 R18 R21 R22 DCB/ns 5-5 R2 R3 R4 R18 R21 R DCB/ns 5-5 GLONASS-M 卫星 DCB R11 R13 R15 R18 R19 R2 DCB/ns 5-5 GLONASS-M 卫星 DCB R11 R13 R15 R18 R19 R

14 Long-term Stability of GLONASS P1P2 DCB Some Glonass satellites have a little large long-term trend. Most Glonass- M are better than Glonass satellites.

15 Monthly variations of GLONASS satellite DCBs 1 GLONASS 卫星 DCB DCB 月稳定性 1 R2 R3 1 GLONASS-M 卫星 DCB 月稳定性 R11 DCB 1 R unit: ns R4 R R18 R22 unit: ns R15 R R18 R Most are less than 2 ps.

16 Short-term stability of GLONASS P1P2 DCB Daily variation 1 week 2 week.. 8 week variation Dif between 4weeks and week: GLONASS 9-16ps,GLONASS-M 4~6ps

17 4. Galileo DCB Analysis GAL E1-E5a DCBs for GPS/Galileo/BDS combined estimation mode determined as compared to DLR

18 The number of receivers involved in the estimation of GAL DCBs

19 Long-term Stability of Galileo DCB DCB E11 E12 E19 E1-E E1-E5a E1-E5b Standard deviations for GALILEO satellite differential code biases for the entire time series (units: ns)

20 Short-term stability of Galileo DCB Time ranged stability statistics (E1-E5, E1-E5a, and E1-E5b) differential code biases (unit: ns) PRN DCB 7d 14d 21d 28d 35d 42d E1-E E11 E1-E5a E1-E5b E1-E E12 E1-E5a E1-E5b E1-E E19 E1-E5a E1-E5b Comparison of the STDs for the 4weeks and week interval shows that the maximal difference does not exceed 1ps for all satellite DCBs. This indicates it is practical to provide post users with monthly-averaged GAL satellite DCBs.

21 5. BDS DCB Analysis (a) B1B2 DCBs (214) (b) B1B3 DCBs ( 214) Beidou satellite (DCBs) calculated together with ION GIM from GPS/BDS observations in SHAO igmas Analysis Center with about 4 BDS tracking stations.

22 Long-term Stability of BDS B1B2 DCB Standard deviations for Beidou DCbs (units: ns) TYP GEO IGSO MEO PRN C1 C2 C3 C4 C5 C6 C7 C8 C9 C1 C11 C12 C13 C14 B1-B B1-B IGSO with the best stability, most less than 15ps,GEO is the worst.b1b3 is a little big than B1B2.

23 Short-term stability of BDS B1B2 DCB GEO IGSO MEO PRN 7d 14d 21d 28d 35d 42d C C C C C C C C C C C C C C A comparison for the 4weeks and week interval showed that the STD differences did not exceed 6ps for all B1 B2 satellite DCBs.

24 Short-term stability of BDS B1B3 DCB PRN 7d 14d 21d 28d 35d 42d GEO IGSO MEO C C C C C C C C C C C C C Comparison for the 4weeks and week interval showed that the STD differences did not exceed 4ps for all B1 B3 DCBs. This clearly illustrates the viability of using monthly-averaged BDS satellite DCB in BDS post-processing.

25 BDS tracking stations BDS GEO DCB stability with the tracking stations expandation

26 BDS tracking stations BDS IGSO/MEO DCB stability with the tracking stations expandation

27 Summary With present calculate method, there re biases in GNSS DCB series due to the satellite number changes. Before the stability analysis of DCB series estimated together with ionosphere, the biases have to be removed firstly. The stability of GNSS satellite DCB is correlated with the ground tracking network. BDS and Galileo DCB will be better if there re more stations. For BDS/Galileo,the monthly mean value can be used in post-processing.

28