We consider the operation of a digital linear ion trap with resonant radial ejection. A sequence of rectangular voltage pulses with a dipole resonance signal is applied to the trap electrodes. The periodic waveform is piecewise constant, has zero mean, and is determined by an asymmetry parameter : one value is taken on interval and another on , where is the RF period. Ion mass scanning is performed by varying the asymmetry parameter and amplitude of the negative pulse part with time.