Recent flex power changes

Abstract

The redistribution of the transmit power among different GPS signal components is called flex power, and it is implemented on modernized GPS satellites starting with Block IIR-M. The purpose of the flex power is to increase signal protection against jamming. It has been mostly active since the beginning of 2017 in different flex power modes and is visible in the carrier-to-noise density ratio (C/N0) observations as stepwise changes. Especially after the beginning of 2020, the flex power modes changed frequently. We summarize these changes and study their impact on differential code biases (DCBs) which is 0.3 ns on average for L1 and L2 intra-frequency DCBs. The flex power is analyzed daily using C/N0 measurements of the globally distributed GNSS observations network from January 1, 2020 until February 28, 2022. The flex power activation times are written into a dedicated block of the SINEX metadata format.