“The move is part of a growing trend. Over the last decade, other large police departments in Chicago, Baltimore, Washington, D.C., and Portland have all encrypted their radio communications or are planning to do so. Departments say broadcasting in the clear gives criminals advance warning. Beltran said encryption would also protect the information of crime victims and block pranksters who jam up NYPD frequencies. (The NYPD regularly leaks information on arrestees and even victims for political purposes.)
However, scanner enthusiasts, news organizations, and elected officials complain that encrypted radio is cutting off a longstanding and useful source of information on police activity.”