Apparatus and analysis method for determination of moisture in materials

A method of estimating moisture content in a material comprising:

• (a) obtaining measured data including measured phase data, actual moisture content data, and weighting data, where the weighting data is representative of the material mass per unit area of the material for which moisture content is to be estimated;
• (b) setting up a first modelling function to model any non-linearity in said weighting data, said first modelling function having a first set of coefficients;
• (c) setting up a second modelling function relating estimated moisture content to measured phase and said first modelling function, said second modelling function having a second set of coefficients;
• (d) determining values of said first and second sets of coefficients which minimise error between estimated moisture content and actual moisture content for said measured data;
• and
• (e) estimating moisture content using said first and second modelling functions with said determined values of said first and second sets of coefficients.

Apparatus for estimating moisture content in a material, including:

• a transmitter for directing a first frequency (f1) signal and a second frequency (f2) signal through a material;
• a receiver for receiving said first and second frequency signals;
• determining means for determining a first absolute phase shift (φ1) of said first frequency signal and a second absolute phase shift (φ2) of said second frequency signal;
• transformation means for transforming φ1 to a first corrected absolute phase shift (φ1c) and φ2 to a second corrected absolute phase shift (φ2c) in accordance with an expected relationship between φ1 and φ2, wherein said expected relationship is φ1=Kφ2f1/f2, where K is a constant that takes into account dispersion of the material at the first and second frequencies;
• and
• moisture content estimating means for estimating moisture content from φ1c and φ2c.

Apparatus for estimating moisture content in a material, comprising:

• a transmitter for directing a first frequency (f1) signal and a second frequency (f2) signal through a material;
• and
• a receiver for receiving said first and second frequency signals,
• wherein the apparatus is configured to determine a first absolute phase shift (φ1) of the first frequency signal and a second absolute phase shift (φ2) of the second frequency signal;
• to transform φ1 to a first corrected absolute phase shift (φ1c) and φ2 to a second corrected absolute phase shift (φ2c) in accordance with an expected relationship between φ1 and φ2, wherein the expected relationship is φ1=Kφ2f1/f2 and K is a constant that takes into account dispersion of the material at the first and second frequencies;
• and to estimate moisture content from φ1c and φ2c.