Observed solar radio burst effects on GPS/Wide Area Augmentation System carrier-to-noise ratio

The first direct observations of Global Positioning System (GPS) L1 (1.57542 GHz) carrier‐to‐noise ratio degradation due to a solar radio burst are presented for an event that occurred on 7 September 2005. Concurrent carrier‐to‐noise ratio data from GPS satellites are available from receivers at Arecibo Observatory, Puerto Rico; San Juan, Puerto Rico; and also from Anderson, South Carolina, United States. The right‐hand circularly polarized (RHCP) signals from this solar radio burst caused a corresponding decrease in the carrier‐to‐noise ratio of about 2.3 dB across all visible satellites. The maximum solar radio burst power associated with this event was 8700 solar flux units (1 SFU = 10−22 W/m2/Hz) RHCP at 1600 MHz. Direct observations of GPS semicodeless L2 carrier‐to‐noise ratio degradation from receivers in Brazil are also presented for a solar radio burst that occurred on 28 October 2003. The maximum degradation at GPS L1 was about 3.0 dB, and a degradation of 10.0 dB was observed on the semicodeless L2 signal. Scaling to historic solar radio burst records suggests that GPS L1 receivers could fail to produce a navigation solution and that semicodeless L1/L2 receivers will fail.