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New digital mode puts beacon off air

Date : 20 / 12 / 2017
Author : Jim Linton - VK3PC

A clash has occurred on 6-metres in Australia with the popular FT8 digital mode, introduced in June 2017 nominating 50.313 MHz as a worldwide operating frequency, already occupied by a propagation beacon. The Barossa Valley beacon VK5RBV has been switched off to avoid interfering with stations running FT8. Mind you, VK5RBV has been operating for many years on 50.315 MHz, but the developers of FT8 have nominated 50.313 MHz as its operating frequency.

The WIA Technical Advisory Committee is carefully looking at the matter and welcomes input as it looks for a new beacon frequency. The obvious choice would appear to be the band segment beginning at 50.400 MHz. This segment has already been adopted by IARU Region I as its new exclusive beacon segment, and it is logical for us to follow the same path.

This may be a forerunner of similar clashes as more new digital modes come into use in the same part of the band. FT8 is also becoming popular on 2 metres, and may be ideally suited on a group of spot frequencies recommended for modes of different bandwidths. The narrow band channel on 144.320 MHz is the logical one for FT8 in the WIA band plan, but it's noted that 144.313 MHz has also been used for FT8.

The new digital mode of HF at weak signal levels lower power levels and almost any antenna is enabling lots of contacts, but the trend on 6m seems to be to use it on high power levels.
FT8 in its description has been designed for sporadic E propagation where signals may be weak and fading, openings may be short in duration, enabling fast completion of reliable QSOs.


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