ELT activation
A remotely positioned test switch activates them momentarily to confirm RF output level and antenna operation but generally sends a different signal to an accident signal
To a previous poster : The antenna is generally a flush insulated slot section type cut and bolted into a metal (i.e. RF blocking) airframe . . the same may still be true of composite airframes as they have quite a lot of metal mesh included in them to address lightening strike issues and that might reduce signal strength