As we dive into the world of college radio broadcasting, one term which comes up over and over is “carrier current”. What exactly is carrier current and why is it important to college radio history? Let’s take a look.
Carrier current broadcasting is a way to transmit a radio signal through the electrical wiring of a building (or in the case of a college campus, several connected buildings). This type of broadcasting doesn’t require an FCC license, because you are not transmitting over-the-air. It was a great, inexpensive way for colleges to broadcast to the student dorms and other campus buildings without the effort and expense of setting up an AM transmitter, tower, etc.
The downside, of course, is that the signal is pretty limited geographically. You can usually only tune in to a carrier current station if your radio is plugged into an electrical outlet in a connected building, although some systems can transmit the signal up to 50m from the electrical wiring. This limited most college stations to broadcasting only to their own campus, with residents of the surrounding community generally being unable to tune into the signal.
While you might guess that this type of “wired wireless” broadcasting predated over-the-air transmissions, that isn’t the case. This is because while the underlying concept was invented in 1898, the technology required to implement a carrier current system didn’t exist until around 1920. It would be 1936 before the first college introduced a carrier current station, when Brown University inaugurated the “The Brown Network”. The idea spread quickly, particularly in the Northeast U.S., and soon their were dozens (and then hundreds) of college radio stations operating a carrier current system.
While many college radio stations went on to obtain FM radio licenses, or adopted other broadcasting concepts such as closed-circuit cable or internet streams, there are still a number of carrier current stations still operating today. The stations have the advantage of being fully commercial stations in terms of advertising, since they do not have to adhere to FCC licensing rules and regulations regarding non-profit and educational broadcasting. These stations are keeping alive a technology that helped to make college radio a reality.