Congratulations to the Case Amateur Radio Club for their second place score (out of 114 entries nation-wide) in the ARRL’s Frequency Measurement Test! The hosts of this year’s HamSCI workshop, W8EDU was able to measure the frequency of one 80 meter and one 40 meter transmission from K5CM to 0.03 and 0.02 Hertz, respectively. First place station W4VU in North Carolina won by only a slight margin of 0.01 Hz on 80 meters (a difference of one part per billion in the measurement).
Plain Language Summary: Radio communications using the high‐frequency (HF) bands (3–30 MHz) is important for emergency communications because it is the only form of electronic communications that can travel over the horizon without relying on man‐made infrastructure such as the Internet, satellite systems, or phone networks. This is possible because HF rays can be bent back to Earth by the ionosphere, an electrically charged layer of the upper atmosphere. Space weather events such as X‐ray flares from the Sun and geomagnetic storms can alter the ionosphere to disrupt these communications. During September 2017, a significant number of solar flares and geomagnetic activity occurred. Simultaneously, major hurricanes, including Hurricane Irma and Hurricane Jose, caused situations in the Caribbean region requiring the use of emergency HF communications, often provided by ham (amateur) radio operators. This paper shows the impacts of these space weather disturbances on HF communications as observed by multiple ham radio monitoring systems.