beam forming and steering networks are operated such that the transducer elements electronically coupled to the beam forming and steering network ca transmit and receive ultrasound energy at a desired angle such as p or p this eliminates the need to physically orient the outer transducers at an angle p or p from an axis normal to aiming axis 28a the beam forming and steering networks also provide a pulse generation function for all of the transducers in this mode of operation only one switch module and one beam forming and steering network set is needed to be electronically coupled to transducers 101 140 for discussion purposes it will be assumed that beam forming and steering network 4 is used to generate a tracked transducer beam from tracked transducer array 107 109 the tracked transducer beam upon entering the target medium is misdirected by an angle t from aiming axis 28a along axis 32 tracking transducers 61 63 69 71 and 77 79 each receive ultrasound energy from the tracked beam the time required for ultrasound energy to travel from the tracked transducer array to the three tracking transducer arrays is measured and recorded by computer 23 once travel time measurements are obtained for each tracking transducer phased array switch modules 1 3 are manipulated to change the individual transducer elements which make up each phased array this is the physical equivalent of relocating the transducers in the phased array in the present embodiment the transducer elements constituting the left outer tracking transducer are switched from 61 63 to 62 64 the transducer elements constituting the central tracking transducer are switched from 69 71 to 70 72 the transducer elements constituting the right outer tracking transducer are switched from 77 79 to 78 80 travel times.