I live next to the river Weser and during a walk outside our little village we regularly walk by the local radar Tower. It emits a beacon signal for the ships on the river for them to calculate their exact position.
Not all ships (especially the old ones) have gps and the tower was built before it became so accurate for civilian use.
It still operates to this day.
This picture was taken by me with cellphone camera Xiaomi Redmi note 10.
Feel free to use it, no credit necessary.