Articles by: Dave, NK7Z, (ARRL Technical Specialist, RFI) on using a SDR receiver to identify RF interference (RFI). Dave presents a series of articles on his web site to assist in identifying RFI using relatively inexpensive tools (SDR Play RSP1 and HDSR for example).
https://www.nk7z.net/sdr-rfi-survey-p1/
The RFI Snapshots article provides images of RFI sources to assist you in identifying RFI sources.