Data channel only for mobile computers /work stations etc, very common here in BC, all over the place. The other thing is it could be a new frequency so radio shop leaves in on test for a predetermined time 24/7 365, to see if it interferes with other user on same frequency or adjacent ones , looking for spurious etc.
All repeaters undergo this, so its just dead carrier at the end of day. You could be witnessing a new repeater, but without the exact frequency, we are stabbing in the dark