GPS IIR‐M L1 Transmit Power Redistribution: Analysis of GNSS Receiver and High‐Gain Antenna Data

Abstract

All seven operational GPS Block IIR‐M satellites experienced short maintenance periods in February 2017. It was later identified that the satellites' transmit power of different L1 signal components had been changed during this maintenance. The total radiated power of the satellites remains constant, but the powers of the C/A‐code and the P(Y)‐code signals have increased while the powers of the M‐code and the intermodulation product have reduced. Further examination reveals a more efficient use of the total available power on the spacecraft as more power is available for the three navigation signals on L1. Observations from geodetic GNSS receivers were analyzed to demonstrate the effect of the change in L1 signal power distribution on the measured C/N0 of the C/A‐code and P(Y)‐code for different receiver types. High‐gain antenna data collected before and after the maintenance periods are used to analyze improved utilization of the available power through the reduction of the losses caused by the intermodulation product.