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[SGD02-06] Differences in receiving antenna phase characteristics of GPS and GLONASS and their effects
Keywords:GNSS, phase characteristics, GEONET
The observation data of GEONET are affected by radome and multipath from antenna mount, and their correction for each combination of antenna and monument type is indispensable for precise analysis. The phase center corrections (PCC) currently used in the current routine analysis system of GEONET were obtained by field calibration experiments, which include the above effects, and derived from dual frequency (L1 and L2) data of GPS. In the efforts we have made to incorporate GLONASS into the analysis, we have applied the GPS-derived PCC to GLONASS data, too, as an approximation.
The frequency bands of the L1 and L2 bands are slightly different between GPS and GLONASS, and the PCC derived for GLONASS frequencies have been gradually incorporated and applied in the International GPS Service (IGS) after the IGS08 model. Dach et al. (2011) evaluated the impact of the GLONASS-PCC for satellite transmitting and receiving antennas using the IGS global network, although the effect on the orbit determination of the GLONASS satellite is remarkable, impact on the bias of site coordinates is within 1 millimeter for height component. However, this results is for combined solutions of GPS and GLONASS. In order to make clear the impact of the GLONASS-derived PCC and their properties, it is appropriate to first evaluate the effect on the analysis by GLONASS alone.
We analyzed data of the field calibration experiment which were conducted by Geographical Survey Institute from February to March 2019 and acquired the GLONASS data in addition to GPS, to evaluate the difference in PCC between GPS and GLONASS and their effects. BERNESE ver. 5.0 software was used for the analysis, and the PCC of the L1 and L2 were first estimated for GPS and GLONASS, respectively. Next, using the same data, baseline analysis was performed using GLONASS data for each antenna-mount type combination with applying the GLONASS-derived PCC and the GPS-derived PCC instead, respectively. The obtained baseline solutions were compared with those obtained with GPS data analysis.
Preliminary result shows significant difference of several mm to a maximum of 1 cm in height between the GLONASS solution obtained by GPS-derived PCC and the GPS solution. The difference depends on combination of the antenna and the monument type. On the other hand, when the GLONASS-derived PCC is applied, the difference from the GPS solution is about 3 mm or less and 1 mm or less, respectively, and 5 mm and 2 mm at the maximum, respectively, in the height and the horizontal component, respectively. This result shows that ignoring difference of PCC between GPS and GLONASS may introduce an internal inconsistency of up to about 1 cm into the combined solutions, and suggests the necessity of calibration and correction of GLONASS-specific PCC to prevent it.
The frequency bands of the L1 and L2 bands are slightly different between GPS and GLONASS, and the PCC derived for GLONASS frequencies have been gradually incorporated and applied in the International GPS Service (IGS) after the IGS08 model. Dach et al. (2011) evaluated the impact of the GLONASS-PCC for satellite transmitting and receiving antennas using the IGS global network, although the effect on the orbit determination of the GLONASS satellite is remarkable, impact on the bias of site coordinates is within 1 millimeter for height component. However, this results is for combined solutions of GPS and GLONASS. In order to make clear the impact of the GLONASS-derived PCC and their properties, it is appropriate to first evaluate the effect on the analysis by GLONASS alone.
We analyzed data of the field calibration experiment which were conducted by Geographical Survey Institute from February to March 2019 and acquired the GLONASS data in addition to GPS, to evaluate the difference in PCC between GPS and GLONASS and their effects. BERNESE ver. 5.0 software was used for the analysis, and the PCC of the L1 and L2 were first estimated for GPS and GLONASS, respectively. Next, using the same data, baseline analysis was performed using GLONASS data for each antenna-mount type combination with applying the GLONASS-derived PCC and the GPS-derived PCC instead, respectively. The obtained baseline solutions were compared with those obtained with GPS data analysis.
Preliminary result shows significant difference of several mm to a maximum of 1 cm in height between the GLONASS solution obtained by GPS-derived PCC and the GPS solution. The difference depends on combination of the antenna and the monument type. On the other hand, when the GLONASS-derived PCC is applied, the difference from the GPS solution is about 3 mm or less and 1 mm or less, respectively, and 5 mm and 2 mm at the maximum, respectively, in the height and the horizontal component, respectively. This result shows that ignoring difference of PCC between GPS and GLONASS may introduce an internal inconsistency of up to about 1 cm into the combined solutions, and suggests the necessity of calibration and correction of GLONASS-specific PCC to prevent it.