"Top Band Dragon's Fire" signal blanketing 160 meters in Asia

The IARU Monitoring System (IARUMS) says radio amateurs in Japan and elsewhere in Asia and Oceania are reporting an unidentified intruder signal on 160 meters. In Japan, the wideband signal, which IARU Region 2 Monitoring System Coordinator Bill Zellers, WA4FKI, has dubbed "Top Band Dragon's Fire," reportedly began transmitting continuously about October 1, blanketing 160 meters rendering it useless for Amateur Radio work. The signal, which has been detected in parts of the US Northwest, was first heard as long ago as December 2004. Reports indicate that the signal turns up at different times at different locations. In some cases, it's only during so-called "gray line" propagation, while others hear the signal 24/7. Near Perth, Australia, the intruder was heard slowly rising out the noise floor about a half-hour after sunset, increasing to around S7 and remaining long into the night. "The intruder is detectable from approximately 1700 kHz up to about 1930 kHz," said one report that likened the sound to "a diesel motor with a ticking sound at a constant rate which is evenly spread across the band." Stations in the US Northwest have heard the signal at about 1830 kHz on a north-pointing Beverage. Amateurs in Singapore report that the signal recently shifted from wideband noise to a pulsed signal. Reports also have arrived from New England. Veteran Top Band DXer Tom Rauch, W8JI, in Georgia says he can "just detect a noise floor increase some mornings," but was unable to identify an actual signal. Forward reports to Chuck Skolaut, K0BOG, at ARRL Headquarters.

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