A method and a device for non-invasive vibration-based condition monitoring of a machine placed on a physical frame of reference, using a time-domain broadband magnetoresistive sensor having a sensor transfer function of electric resistance versus magnetic field intensity, said machine comprising an attached magnet or a magnetic part; comprising the steps of: placing the magnetic sensor on said physical frame of reference at a distance from the machine and at a predetermined distance from the magnet or magnetic part, such that the magnetoresistive sensor is operating in a dynamic part of the sensor transfer function in respect of the magnetic field produced by the magnet or a magnetic part; capturing a time-domain magnetic field signal transduced by the sensor; and using an electronic data processor to process the captured signal to obtain a vibration-based indicator of the machine's condition.

A method and a device for non-invasive vibration-based condition monitoring of a machine placed on a physical frame of reference, using a time-domain broadband magnetoresistive sensor having a sensor transfer function of electric resistance versus magnetic field intensity, said machine comprising an attached magnet or a magnetic part; comprising the steps of: placing the magnetic sensor on said physical frame of reference at a distance from the machine and at a predetermined distance from the magnet or magnetic part, such that the magnetoresistive sensor is operating in a dynamic part of the sensor transfer function in respect of the magnetic field produced by the magnet or a magnetic part; capturing a time-domain magnetic field signal transduced by the sensor; and using an electronic data processor to process the captured signal to obtain a vibration-based indicator of the machine's condition.

An L-mode guided wave sensor 10 for inspecting an inspection target by using an L-mode guided wave. The L-mode guided wave sensor 10 is provided with a vibrator 3 which is attached to an inspection target 1, and a coil 5 which is wound around the vibrator 3 and to which an AC voltage is applied. The vibrator 3 is made of a ferromagnetic material.