Fig. 3From: ScintPi 2.0 and 3.0: low-cost GNSS-based monitors of ionospheric scintillation and total electron contentSummary of L1 (~ 1.6 GHz) S4 measurements made by ScintPi 3.0 (red curves) and collocated Septentrio PolaRx5S (black curves) on December 27, 2021. These monitors were collocated in Presidente Prudente (PPR), Brazil. The blue curves represent satellite elevation angles. The constellation and satellite identifier number are indicated in each panelBack to article page