1. A machine tool monitoring device of a machine tool for machining a work piece, comprising: a signal unit ( 24 ) provided for an ultra-broad-band operation, wherein the signal unit ( 24 ) has a programmable data base ( 44 ) in which a use situation ( 52 , 58 ) in a machining process is associated with a procedure ( 56 , 60 ) for changing the machining process, wherein the signal unit ( 24 ) includes an arithmetic-logic unit ( 40 ) that is provided for associating a detected signal ( 34 ) with a use situation ( 52 , 58 ) by means of a fuzzy logic-based and/or neural logic-based signal processing.