Short-term heart rate variability (HRV) analysis based on spectral methods has been widely applied to assessment of autonomic nervous system activities for many physiological and mental disorders. Recently, homecare devices designed for heart monitoring have attempted to include HRV analysis function. These homecare devices based on some microprocessors with low computational power might encounter difficulty in implementing HRV spectral analysis for real-time applications. Therefore simple and less computation consuming methods to calculate frequency domain HRV indicators are needed.