Fig. 4From: ScintPi 2.0 and 3.0: low-cost GNSS-based monitors of ionospheric scintillation and total electron contentSummary of L2 (~ 1.2 GHz) S4 measurements made ScintPi 3.0 (green curves) and Septentrio PolaRx5S (black curves) on December 27, 2021. These monitors were collocated in Presidente Prudente (PPR), Brazil. The blue curves represent satellite elevation. The constellation and satellite identifier number are indicated in each panelBack to article page