Impact of flex power on GPS Block IIF differential code biases

Özge Gizem Esenbuğa,André Hauschild

doi:10.1007/s10291-020-00996-x

Abstract

GPS Block IIF satellites are able to redistribute the transmit power between the signal components. This ability is called flex power, and it has been developed as a remedy against jamming. Since it is operationally not possible to increase the transmit power for all signal components simultaneously, a redistribution between them is necessary under certain operational situations. Flex power has been active on Block IIF satellites since January 2017 over a specific regional area and has an impact on differential code bias estimation as well as the signal-to-noise density ratio. A network of the International GNSS Service stations containing only Septentrio PolaRx5 and PolaRx5TR receivers between August 1 and November 21, 2019 has been used for differential code bias estimation using GPS L1 C/A, L1 P(Y), L2 P(Y), and L2C signals with and without consideration of the flex power in the estimation process for Block IIF satellites. The estimation results are compared with the German Aerospace Center as well as the Chinese Academy of Sciences DCB products to validate the results.

Highlights

The Block IIF satellites are the fourth generation of the GPS satellites
The flex power mode discussed here is the one that is empowered since January 2017 on the Block IIF satellites, and its signature is a power increase by 2.5 dB-Hz of the L1 C/A and P(Y) signals over an area centered at the geographic location 41°E and 37°N
The flex power has been activated over a specific regional area for GPS Block IIF satellites (Steigenberger et al 2018)

Summary

Introduction

The Block IIF satellites are the fourth generation of the GPS satellites. These satellites provide the new L5 signal in addition to the legacy GPS L1 C/A code, L1/L2 P(Y) code signals, the civil L2C signal on L2, and the military M code on L1/L2. The flex power mode discussed here is the one that is empowered since January 2017 on the Block IIF satellites, and its signature is a power increase by 2.5 dB-Hz of the L1 C/A and P(Y) signals over an area centered at the geographic location 41°E and 37°N. It has been shown in the previous research that flex power has an impact on pseudorange biases (Steigenberger et al 2018). The pseudorange biases occur due to the differences in the chip shape distortions among the GNSS satellites. In case two different GNSS code signals on the same or different frequencies are used together, their pseudorange biases are not the same causing a differential code bias (DCB)

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Summary and conclusion