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The solar panel of non-geostationary GNSS spacecrafts may not always be perpendicular to the Sun irradiation direction due to attitude errors and mounting misalignment, which affects the modeling of solar radiation pressure (SRP). This study presents the effects of commanded pitch-attitude biases for solar panels on SRP and orbit solutions. From the collected telemetry information, the solar panel B (SP-B) of BeiDou-3 M215 satellite underwent pitch-maneuvers around the body-fixed Y-axis on days of year 65–67 of 2024, and was then kept perpendicular to the body-fixed X-axis (pitch-fixed mode). SRP biases due to the SP-B pitch-maneuvers exhibit remarkable discontinuities in the D (satellite-Sun) direction that cannot be accounted by traditional ECOM1 and ECOM2 SRP models. This is devastating for M215 precise orbit solutions. When combining the ECOM1 and box-wing model (ECOM1 + BW) with telemetry SP-B orientation information, the three-dimensional orbit consistency reaches 10.7 cm, with improvements of about 95.9% and 96.0% relative to the ECOM1 and ECOM2 solutions. SLR (Satellite laser ranging) residual mean and standard derivations decrease from 0.815 ± 0.399 m and 1.219 ± 0.670 m to - 0.078 ± 0.018 m for ECOM1 and ECOM2 solutions, respectively. For SP-B orientation in pitch-fixed mode, the derived SRP has a twice-per-revolution signal in D similar to that of satellite body, but with opposite harmonic phases and amplitudes greater by a factor of 2–4. SRP perturbation induced by SP-B largely neutralizes the satellite body contribution, thus dominating and changing the total SRP harmonic phases in D. This feature change results in opposing Sun-elongation-angle-dependent systematic patterns of de-trended clocks obtained with ECOM1 model for SP-B in nominal and pitch-fixed orientations, which is not seen in the solutions using ECOM1 + BW model and ECOM2 model. As evidenced by reduced orbit overlap differences, SLR residuals and de-trended clock residuals, and more stable SRP parameter estimates, the ECOM1 + BW model clearly outperforms the ECOM1 and ECOM2 models for SP-B orientation in pitch-fixed mode. [ABSTRACT FROM AUTHOR]

The potential for achieving assured restoration accuracy of primary signals is analyzed in light of previously obtained results of studies designed to increase the accuracy of measurements and reduce losses of telemetry information due to errors in the selection of the anticipated range of measurements under the conditions of rigid constraints on the throughput of an Earth-space vehicle channel. The essential features of the improved algorithm for conversion of primary signals in an onboard information telemetry system are briefly described. [ABSTRACT FROM AUTHOR]