I just spent two days in Tallinn, where I had a place just opposite of Kaarli kirik, with the window facing towards Toompea.
Every morning at 7am, I woke up to a short melody that seemed to be played by a brass ensemble. The piece is some 9 measures long and repeats 3 times (the last two or three notes are held a bit longer on the third repetition).
This is approximately how it sounds (score recreated from memory):
What is this piece, and where does it come from?