The ortho-normalized volume magnetic source (ONVMS) technique is applied to a new time domain EMI instrument called portable decoupled electromagnetic induction sensor (PEDEMIS); The system provides multiple deployment options (carted or carried); multimode operation (detection, interrogation, deep detection, wide interrogation); multi static data that is collected with flexible, decoupled and detachable sensors with precise positioning. In this paper we first describe the geometries of the PEDEMIS transmitters and receivers, then present the procedures to model the way they establish primary fields and measure subsurface responses, and, finally, illustrate the comparisons between modeled and actual data.