A method and apparatus for positioning a probe inside a patient including a plurality of transmitter/receiver nodes arranged around the patient for communicating with the probe and generating navigation signals, a system for generating one or more positional signals in response to the navigational signals, and a system for collecting and analyzing those positional signals to determine the location of the medical instrument inside the patient's body. The transmitting/receiving nodes may be arranged on a flexible blanket which is wrapped around and adhered to the patient's body or over a table supporting the patient's body.