Observations of over-the-horizon (OTH) radar interference on amateur bands top all others

The volume of reports of over-the-horizon (OTH) radar interference from observers working with the International Amateur Radio Union (IARU) Region 1 Monitoring System (IARUMS) dwarfs that of all other interference sources, the November IARUMS newsletter reports.

Nearly 800 OTH radars were observed during November alone and the total number of reports for the year is more than 4 500 although that number likely includes multiple reports of the same OTH radar systems.

While the intruder watcher is focused on IARU Region 1, much of the major interference it recounts can affect the amateur bands in the world’s other two IARU regions. IARUMS has tracked most OTH radar signals to sites in Russia and China, but a recent report indicated that India has an OTH radar system in the works. IARUMS is calling the system “of concern,” although it is not known what frequencies it may use.

During 17 to 21 November, IARUMS reported a “strange, somewhat washed-out signal” about 7 kHz wide, that “drifted slowly back and forth” on 40 meters and below.

The IARUMS Newsletter is available on the IARU Region 1 web site at www.iaru-r1.org.

SARL