Another option is a whistle.
They are easy to mount, small diameter and vertical. They can be very loud, depending on air pressure and air VOLUME (CFM). They make a crisp, clear unidirectional sound. This is very handy to bounce an echo for audible ranging.
The down side is that they use LOTS of air. This one uses 56 CFM at 100 PSI.
A small whistle, like this Kahlenberg 115
is a nice option. An air solenoid
would permit remote
mounting / electrical
pushbutton switch control, so this could be mounted anywhere up high on the mast
Here is a test A/V clip
of my Kahlenberg 115 whistle.