Keeping a watch on the 40-metre band

With four weeks to go before broadcast stations are due to have migrated from the band 7100-7200kHz as that band is restored to the Amateur Radio Service, a scan watch has begun to identify stations still currently using that segment.

IARU Region 3 Monitoring Systems Coordinator, B.L. (Arasu) Manohar VU2UR has been scanning the segment.

He did this for four days recently to identify 58 broadcast transmissions, their frequencies, times and signal strengths. The broadcasters use 5kHz channel spacing.

The worthwhile yet painstaking task also notes the languages of the transmissions including Arabic, Burmese, Chinese, English, French, German, Indian, Japanese, Russian and Turkish.

Adding to the complexity of the task are jamming stations, heterodynes, low powered regional or domestic stations and many powerful broadcasters using relays to cover their audience target area.

Arasu VU2UR says similar scanning and monitoring work may be necessary in other parts of the world to get a fuller picture of broadcast activity and he's prepared to share the spreadsheet result of his work.

Mapping of broadcasters on the 40-metre band will be important should the IARU need to mount a case to fight any continued occupancy of the 7100-7200kHz after 29 March.

That is the departure date set by the World Radio Conference 2003 and coincides with the new broadcasting schedule for 2009.


Jim Linton VK3PC
Wireless Institute of Australia