A method of monitoring the condition of a machine is provided. The method includes receiving an input complex signal from the machine wherein the input complex signal has a plurality of signal components. The plurality of signal components includes at least one signal component containing a pre-determined frequency of interest and at least one signal component containing noise. The method further includes processing the input complex signal and generating an output complex signal having a plurality of signal components The plurality of signal components includes at least one signal component containing a pre-determined frequency of interest and at least one signal component containing noise. Processing the input complex signal includes executing a fixed-step integration and processing the output complex signal to assess whether a fault exists.