Jovian electron cyclotron emissions are intense narrow-banded emissions, generated by energetic electrons spiraling along the magnetic field lines of Jupiter and its magnetized moons. The frequency bands of the electron cyclotron emissions occur at harmonics or very precise multiples of the electron cyclotron frequency, a characteristic frequency of the plasma surrounding the planet.

The frequencies of the electron cyclotron emission bands track the variations in the electron cyclotron frequency, which varies with the strength of the magnetic field. The resulting tones are high- pitched monotones which move up and down in frequency scale on time scales of seconds to tens of seconds.

These signals were recorded by the Voyager 2 plasma wave instrument during the flyby of Jupiter on July 5, 1979.