A method of measuring biaxial stress in an object of a ferromagnetic material in which material in a region in the vicinity of a surface of the object is subjected to a conditioning method by application of a conditioning magnetic field that is at least initially at a high field strength. A device range checking unit sequentially extracts device notations indicating consecutive areas and commands specifying consecutive devices present in a sequence program, expands devices of the corresponding consecutive areas, and checks whether or not devices of consecutive areas are within a range of devices stored in the storage unit. In such situations, the transmitter may use the power control signals from more than one receiver, for example, from the two most dominant receivers in order to focus the beamforming accordingly. The memory also stores a directory that includes a first entry corresponding to the data file. Verification circuitry may compare the digital output test signal with a predetermined reference signal to determine whether the imaging system is functioning properly.