Patent ID: 7078913
Filing Date: 2006-07-18
Classification: G01N

Abstract:
1. A process for determining the moisture content of a material comprising: producing a primary microwave signal with a varying frequency, said signal being a continuously varying signal or a discrete time varying signal, splitting said primary signal to provide first and second microwave signals, said first signal to be transmitted through said material and said second signal comprising an internal reference signal, transmitting said first signal through at least a portion of said material, receiving at a receiver a third signal which comprises potential multi-path interference signals and said first signal which has passed through said material, mixing said third signal together with said second signal, generating a mixed signal, filtering said mixed signal to remove substantially all of said multi-path interference signals, generating a filtered-mixed signal measuring the frequency of said filtered-mixed signal to determine the propagation delay of said first signal after it has passed through said material, and calculating the moisture content of said material from said propagation delay of said first signal after it has passed through said material, wherein the frequency of said primary signal varies sufficiently rapidly that the frequency of said third signal and said second signal will be different when they are received at said receiver.