|Yaesu's System Fusion integrates
conventional analogue FM and digital transmissions on the same
repeater. If you are using a Fusion radio to talk through a Fusion
repeater, the automatic mode selection in the repeater and users mobile
or hand help, switch between the analogue and digital modes without the
user needing to do so. It is a seamless operation.
For amateurs using their conventional FM radios, the repeater operates the same as any analogue FM repeater. Users will notice no difference. However when an amateur uses the digital transmission mode through the repeater, the digital modulation will be heard, sounding similar to packet transmissions. To prevent this, the repeater's FM transmission is encoded with 123 Hz. FM only uses can then set up their radios for 123 Hz CTCSS decode. This results in only the analogue FM transmissions from the repeater being heard. The digital transmission is not encoded with 123 Hz, hence it is not heard on analogue FM radios. However conventional FM users do not have to choose to use the 123 Hz decode if they don't want to or don't have the function in their radio. They will however hear the digital transmissions.
Tests using the CTCSS FM encoding has shown it works well. FM users would not know the repeater is in use unless they look at their S meter. Interference between modes is possible if the FM user, not being aware that the repeater is in use with a digital QSO, transmits. However if the FM user has a weaker signal into the repeater then the digital QSO, the digital QSO will not be interfered with. If the FM user has a stronger signal into the repeater than the digital user, then the repeater will switch to FM and the digital users radios will switch to FM, hearing the FM user. How well this works in practice is yet to be seen, however with the low usage of repeaters, the chance of this happening is low.
The exact operational nature of the Fusion system is yet to be experienced on a wide coverage repeater in Perth, and we look forward to users experimenting with the system, be they conventional FM users or amateurs with Fusion radios.