These signals mimicked some aspects of FRB's that appeared to be coming from outside the Milky Way galaxy, but the possibility of their having an astronomical origin was soon excluded. To track activities near the telescope, the Commonwealth Scientific and Industrial Research Organization (CSIRO) installed a radio frequency interference (RFI) monitor at the Parkes site in December 2014. This form of monitoring became more common as radio-emitting devices became more prevalent on radio telescope sites, including mobile phones, Wi-Fi, and digital televisions. Important information was disclosed by the RFI monitor data, which had not been accessible for earlier peryton discoveries. Each peryton event was accompanied by a period of radio emission at a frequency of 2.5 GHz that was outside the telescope's field of view. These spikes were probably related to the perytons. Hypothesized potential sources of perytons included: