VK CTCSS standardisation

The Wireless Institute of Australia (WIA) National Technical Advisory Committee is now recommending the CTCSS tone of 91.5 Hz for general use on repeaters that require tone access, instead of 123 Hz.

This due to what is known as ‘phantom 123’ that does occur because of music or other factors and falsely triggers repeaters.

A decision in 2004 by VK3 repeater operators was in support of 91.5 Hz because of the unreliability of 123 Hz. The new sub-audible tone had earlier been adopted in VK4 for the same reason.

In Downunder VK the primary use of CTCSS is to overcome interference problems.

Some 2m band repeaters suffer from high powered paging systems operating just above 148MHz, while some 70cm repeaters experience interference from wireless and control devices that share part of the band.

- Amateur Radio Victoria
www.amateurradio.com.au