Importance

Loading Importance Indicators...

Abstract

A process for determining the correlation of signals of an electric impedance tomograph, in which one pair of electrodes each among a plurality of electrodes arranged in an annular pattern on the body is supplied with a harmonically time-dependent excitation current of frequency .omega., and the measured voltage signals u.sub.i(t) of the other passive electrode pairs are multiplied by a signal w(t).multidot.sin(.omega..multidot.t) or w(t).multidot.cos(.omega..multid-ot.t). .omega. is the frequency of the excitation current and w(t) is a window function, and they are subsequently integrated in order to obtain the real and imaginary parts of the signal u.sub.i(t). To avoid a complicated multiplication by w(t).multidot.sin(.omega..multidot.t) or w(t).omega.cos(.omega..multidot.t) in a digital signal processor, provisions are made for a time interval of the signal w(t).multidot.sin(.omega..multidot.t) or w(t).multidot.cos(.omega..multid-ot.t) to be represented by a finite sequence of digital values and for sending these in phase with the harmonic excitation current of frequency .omega. to the digital input of a fast DA converter, while the signal u.sub.i(t) to is sent to the reference voltage input of the DA converter, after which the analog signal sent from the DA converter is integrated and [sic--Tr.Ed.] the integrated analog signal is subjected to an AD conversion and is sent to a computing unit for further processing.

Loading the Abstract Image...

First Claim