An apparatus comprising: an input interface configured to receive an input signal including at least one of vibration and speed information associated with at least one stage of a gearbox; a processor configured to identify a fault in the gearbox using the input signal; and an output interface configured to provide an indicator identifying the fault; wherein the processor is configured to identify the fault by: determining multiple families of frequencies, each of the multiple families of frequencies related to a different failure mode of the gearbox, the families of frequencies including (i) a first family of frequencies comprising a gear mesh frequency and its harmonics and (ii) additional families of frequencies comprising sidebands across the first family of frequencies, the additional families of frequencies associated with different components of the gearbox, wherein each of the multiple families of frequencies includes at least one frequency; decomposing the input signal into different frequency bands in a frequency domain using the families of frequencies; reconstructing a gear signal using the decomposed input signal based on one or more frequencies and one or more amplitudes of the different frequency bands; and comparing the reconstructed gear signal to a baseline signal. an input interface configured to receive an input signal including at least one of vibration and speed information associated with at least one stage of a gearbox; a processor configured to identify a fault in the gearbox using the input signal; and an output interface configured to provide an indicator identifying the fault; wherein the processor is configured to identify the fault by: determining multiple families of frequencies, each of the multiple families of frequencies related to a different failure mode of the gearbox, the families of frequencies including (i) a first family of frequencies comprising a gear mesh frequency and its harmonics and (ii) additional families of frequencies comprising sidebands across the first family of frequencies, the additional families of frequencies associated with different components of the gearbox, wherein each of the multiple families of frequencies includes at least one frequency; decomposing the input signal into different frequency bands in a frequency domain using the families of frequencies; reconstructing a gear signal using the decomposed input signal based on one or more frequencies and one or more amplitudes of the different frequency bands; and comparing the reconstructed gear signal to a baseline signal. determining multiple families of frequencies, each of the multiple families of frequencies related to a different failure mode of the gearbox, the families of frequencies including (i) a first family of frequencies comprising a gear mesh frequency and its harmonics and (ii) additional families of frequencies comprising sidebands across the first family of frequencies, the additional families of frequencies associated with different components of the gearbox, wherein each of the multiple families of frequencies includes at least one frequency; decomposing the input signal into different frequency bands in a frequency domain using the families of frequencies; reconstructing a gear signal using the decomposed input signal based on one or more frequencies and one or more amplitudes of the different frequency bands; and comparing the reconstructed gear signal to a baseline signal.