Multi-frequency information filtering recursion demodulation method

Abstract

The invention relates to a multi-frequency information filtering recursion demodulation method, and is characterized by including the steps of: (1) establishing a recursion equation according to m frequency components f1, f2,..., fm of a multi-frequency excitation system with a known frequency and the sampling frequency fs; (2) from the start moment of a measuring signal, calculating initial values of an information matrix U(k) and a recursion middle matrix K(k) according to data of 2m following sampling point; (3) substituting the initial values and newly increased sampling point data into the recursion equation, and updating U(k) and K(k); and (4) judging whether a demodulation result satisfies system accuracy requirements, if not, returning to Step (3), and if yes, finishing a recursion process, calculating a data matrix Bk, and outputting amplitude and phase data of the m frequency components in the measuring signal. The multi-frequency information filtering recursion demodulation method has the characteristics of being capable of being started without the initial value, simple in iteration, beneficial to hardware implementation and small in occupied resources, and has broad application prospects in aspects of impedance spectrum measurement, electrical imaging and the like.

Description

technical field [0001] The invention relates to a multi-frequency information filtering recursive demodulation method, which belongs to the field of distributed parameter measurement. Background technique [0002] In the fields of industrial multiphase flow detection and medical detection, the electrical characteristics of the measured object are usually relatively complex. For example, the impedance of biological tissue has a characteristic of changing with frequency, and the impedance amplitude and phase of different tissues at different frequencies are different, and they change with the change of excitation frequency. Therefore, in order to obtain more abundant spectral characteristics of the internal electrical parameters of the measured object, more and more impedance measurement systems and electrical imaging systems are not limited to one frequency, and often measure the frequency at two or more excitation frequencies at the same time. Impedance value or boundary im...

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Problems solved by technology

However, these two demodulation methods cannot be started when the initial information is 0, and their recursive process is complic...

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