New GOES Signal Application for Monitoring Ionospheric Irregularities: A HamSCI Collaboration Vision

Radio waves at UHF and VHF frequencies pass largely undisturbed through a smooth ionosphere—for example, in routine EME and AMSAT activities. When the ionosphere becomes turbulent the amplitude, phase and polarization of transionospheric signals will fluctuate, termed “ionospheric scintillation.” Scintillation is often associated with near-equatorial and high-latitude regions but also occurs in mid-latitudes in response to geomagnetic activity. Scientists are only now starting to study continent-scale mid-latitude scintillation patterns in earnest. It has historically been expensive to distribute enough scintillation monitors to cover a region once deemed geophysically uninteresting. Even low-cost GNSS receivers, like ScintPi from the University of Texas, Dallas, approach ~$400 per site. Moreover, GNSS receivers are insensitive at low ionospheric turbulence levels due to the higher radio frequencies used. The NOAA GOES Data Collection System (DCS) provides many, many lower-frequency signals of opportunity that could be used to map out scintillation occurrence in real time. Approximately 33,000 active Data Collection Platforms (DCPs) uplink on hundreds of narrow transmit channels near 402 MHz, relaying ~1 million environmental monitoring messages per day via GOES East and West. These signals downlink at 1.68 GHz and are openly available. A similar DCS exists on European Meteosat and Japanese Himawari satellites. Receiving the signal requires minimal hardware. An RTL-SDR using a manageable dish antenna and a decent preamp should be sufficient. Plus, hobbyist hardware exists for the adjacent GOES images at 1.6941 GHz. A single passive receive site can potentially capture all these DCS links. The challenges are to process the brief transmissions in real time to detect scintillation and to unravel the transmit locations for mapping. The DCP stations are readily identified via their assigned transmission times and frequency channels, but the position information in NOAA’s DCP database is not always accurate. For example, DCP operators manually enter station locations via an arcane fixed-field format and often make mistakes. My hope in interacting with HamSCI is to build up interest to develop an open-source community to address these issues with a goal of generating public maps of basic ionospheric scintillation data for amateur radio and scientific use—including citizen science.