Linear phase alias-free wide frequency band multirate digital filter

In the paper the problem of multirate linear-phase filter realization for "octave property" transfer functions is discussed and illustrated with a practical example. As the example the filter describing the human body tolerance to harmful environmental vibration signals has been chosen. The filter is not easy to implement with classical approaches due to the very specific frequency characteristics defined in a wide frequency range (0.5 Hz to 10 kHz) with a multi-pole 10-15 Hz resonance. The general conditions for proper multirate filter realization are formulated and the filter design based exclusively on linear-phase FIR analyzing/synthesizing filtering sections is discussed. The method has no bandwidth limitations and delivers stable, numerically efficient filtering algorithm. In spite of multiband processing filter has no signal reconstruction errors and has full properties of the classical FIR filter with the extremely long impulse response. Its linear phase makes it superior to IIR realizations.