In-Car Comm Radio interference issues...fix?

Hello, new here.

I’m in law enforcement at a small agency and my in-car radio has a very loud humming noise when I broadcast, sometimes loud enough I am inaudible to coworkers.

When my car is off the hum is gone so I suspect alternator interference maybe?

What products/devices can help mitigate this type of interference? Suggestions GREATLY appreciated!

-Jason