Abstract
Passive sensor systems are attractive for monitoring due to the absence of probing emissions. Two passive systems: an acoustic camera, manufactured by Brüel & Kjær (Sound and Vibration Measurement A/S) and a microwave radiometer are considered in the paper. The performance of these systems is carefully analyzed. The obtained results show the limitations of the acoustic camera in acoustic noise source localization caused by specific side lobes of a pattern of its microphone array. A suggestion how to avoid them is given. Application of microwave bistatic radiometer provides information about thermal electromagnetic radiation of objects in 3D spatial coordinates. The generated radiometric maps contain amplitude and phase information, which is suitable for estimation of displacements/vibration. The received results are applicable in nondestructive testing.