- Excess low frequency noise was observed in granular high Tc films. Random telegraph signal produced by a single, fast two level fluctuator dominated the noise properties of the sample at some particular bias conditions. Exponentially distributed switching rates fall in the MHz range. Apart from simple switching also more complicated three stage processes were observed. Duty cycle of the two level telegraph signal strongly depends on bias conditions. Power spectra of the excess noise signal can be well fitted with a single Lorentzian.