Patent ID: 7135871
Filing Date: 2006-11-14
Classification: G01N

Abstract:
1. A process for determining the moisture content of soil 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 an electrical conductor embedded in said soil and said second signal comprising an internal reference signal, transmitting said first signal through said electrical conductor, receiving at a receiver a third signal which comprises said first signal which has passed through said electrical conductor, mixing said third signal together with said second signal, generating a mixed signal, which said mixing may create upper side band interference signals, filtering said mixed signal to remove substantially all of said upper side-band interference signals created by said mixing, thereby 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 electrical conductor, and calculating the moisture content of said soil from said propagation delay of said first signal after it has passed through said electrical conductor, 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 mixer.