Spread spectrum EIT by code devision multiplexing

Code division multiplexing is proposed as a new EIT method that can provide simultaneous impedance measurements of the multiple channels. Code division provides clear advantages of a wide frequency range at reduced cost and reduced complexity of sources. A potential drawback is the lack of perfectly orthogonal code sets. The method described provides images and spectra which are equivalent to the conventional time multiplexed method, with increases in frequency resolution and measurement speed which may be of benefit in some applications of EITS.