GPS Signal Power change 2019-06-20

Contact: iono@gnss.be

SUMMARY OF THE EVENT: The 20th of April 2018 at 19:48:00 UTC, a false Solar Radio Burst (SRB) warning was issued. Obviously this was not a SRB, as it occurs during the night time in Europe and as our SRB warning is only based on the monitoring of the GPS signal reception (C/N0) of the real-time EPN stations.
The effect detected was due to a progressive change of the signal power of the 19 GPS satellites of the block IIF and IIR-M. As a consequence, the signal reception for the tracking of these satellites was decreased by 2dB-Hz for the L1 C/A and increased by 10 dB-Hz for the L2 P(Y). First satellite operating this change started the 20th of June at 15:18:30 UTC, whereas the last satellite to be reset to previous mode was the 21st of June at 9:27:00 UTC.
This variation of signal strength should not have had an impact on your GNSS applications, as the signal reception fade was smaller than 3dB-Hz.


Carrier to Noise Density Time Series
Carrier to Noise Density Time Series

Figure : Carrier to Noise Density (in red) and its expected behaviour (in blue) for a satellite track at the begining of the event (left) and the end (right)