The Prohibition-Era Origins of the Police Radio

A crime wave fueled the development of one- and two-way radios

12 September 2018

This month The Institute is focusing on crime-fighting technology.

In the 1920s and 1930s, the United States was experiencing a crime wave brought on by Prohibition and the Great Depression. Petty criminals and organized-crime figures began making and selling illegal alcohol following a constitutional ban on the production, importation, transportation, and sale of alcoholic beverages. Bank robberies were on the rise as well, committed not only by gangsters but, in later years, also by those who were out of work because of the Great Depression.

Criminals eluded capture in part because police had no communication system for dispatching patrol cars to a crime scene. That began to change in 1928, when a Detroit patrolman who was an electronics buff developed the first one-way radio link between police headquarters and police cruisers. Five years later, in 1933, a radio engineer and a Bayonne, N.J., police lieutenant improved on that system by building a two-way radio so that patrol cars and police stations could communicate. In 1940 a two-way FM system was introduced in Connecticut.

All three breakthroughs were honored with IEEE Milestones. Information about the achievements can be found on the Engineering and Technology Wiki.


The first police call boxes were installed in major U.S. cities in the 1880s so that citizens could report crimes and patrol officers could talk to each other. By the 1920s, police stations had telephones, and radios were on the rise.

During that period, Detroit’s police department became the first to use a radio station to broadcast alerts about criminal activity. KOP, as it was known, was listed as an entertainment station to meet the licensing requirements of the Federal Radio Commission, the predecessor to the Federal Communications Commission. Those earliest radio stations didn’t have a dedicated frequency and had to be registered with the regulatory agency. Between the station’s recorded music, police made announcements about stolen cars and missing children.

Detroit Police Officer Kenneth R. Cox, a radio buff, was among those on the force who began experimenting in 1921 with installing radio sets in the back seat of a Ford Model T patrol car. The receivers worked, but interference and reflection from the steel and concrete buildings and bridges interfered with the signals. The solution was to move the transmitter to Belle Isle, in the Detroit River between Michigan and Canada and build the 500-watt WCK station (originally W8FS) from which to broadcast.

It took seven years for Cox and Robert L. Batts, an engineering student when the project started, to build a more stable radio receiver and antenna system. In 1928 the Detroit Police Department installed Cox and Batts’ one-way radio system, which allowed headquarters to dispatch an informational call to all patrol cars.

Boston installed the system in 1931, and police departments around the country soon followed.

An IEEE Milestone plaque recognizing the achievement was installed on 1 May 1987 in the harbormaster station on Belle Isle.


One-way radios didn’t allow police to call back to the station to ask for backup or let the dispatcher know they’d arrived at the crime scene. Five years after the deployment of the first one-way system, in 1933, the Bayonne Police Department installed a two-way AM mobile radio system in a patrol car. The system—designed by Lt. Vincent J. Doyle and radio engineer Frank A. Gunther, an IEEE Fellow—combined a transmitter and receiver and used VHF signals. Instead of just receiving calls, the radio enabled back-and-forth communication between a central fixed station and police cars. Questions could be asked and answered, and extra information could be provided. Today’s police radios broadcast on special frequency ranges set aside in the VHF and UHF bands.

The Milestone plaque for this achievement also was unveiled on 1 May 1987. It is located in a municipal park in Bayonne.


Another major technological advancement occurred in 1940, when the Connecticut State Police began operating a two-way FM system. The police commissioner asked IEEE Fellow Daniel E. Noble, a professor of electrical engineering at the University of Connecticut, to design the system. It was built by Fred Budelman, chief engineer at the Fred M. Link Co., a manufacturer of two-way radio communication equipment in New York City. The company’s engineers greatly reduced static, the main problem with the AM system.

Noble attributed the system’s success to choosing phase modulation, selecting proper station sites, using rooftop antennas on patrol cars, and employing different transmitting frequencies for the base stations and mobile units. The system began operating from state police headquarters in Hartford in 1940, leading to a nationwide switch of AM police radios to FM mobile radio, which became the standard.

The Connecticut Milestone plaque, which was unveiled on 1 June 1987, can be viewed in the Hartford building that houses the Department of Public Safety’s State Police Division.

Administered by the IEEE History Center and supported by donors, the Milestone program recognizes outstanding technical developments around the world.

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