Abstract: A method and apparatus for displaying complex impedance and related physical characteristics of an object at a plurality of sinusoidal frequencies over a wide frequency range. Excitation signal waveforms are stored in digital form. Digital sampling and processing circuitry provide high noise immunity and accurate measurement at all impedance phase angles. The technique is particularly well-suited to the measurement of complex impedances in living biological tissue because the digital implementation results in highly accurate measurement values over a plurality of selectable frequencies within a wide sinusoidal frequency region. A novel adaptation of digital cross-correlation and convolution techniques is used to simultaneously display real and imaginary electrical impedance of living biological tissue at several selectable sinusoidal frequencies.