Abstract: The invention concerns a method for monitoring a gear system (1) comprising at least two wheels, each wheel having a characteristic frequency (f1, f2), a vibratory or acoustic signal representative of these vibrations having been acquired by a sensor (21), a vibratory or acoustic digital signal x(t) having been obtained, the method comprising, for each characteristic frequency of the system (1), the steps of filtering (E1) the digital signal by means of a filter in such a way as to obtain an image monitoring signal of at least one vibratory component of at least one defect; determining (E3) the square envelope of said monitoring signal, defined by the square absolute value of the Hilbert transform of the monitoring signal so as to extract an image of the modulating signals associated with the rotation of the wheels from the monitoring signal; determining (E4) the synchronous average of said square envelope relative to the period of rotation of a wheel of interest chosen from the wheels of the gear, said avera

Abstract: A method detects a defect in a vibration sensor including the whitening of the vibratory signal delivered by the vibration sensor, and the calculation of an indicator of asymmetry of the whitened vibratory signal. The whitening may be a cepstral whitening implemented simply by dividing the Fourier transform of the signal by its modulus. The asymmetry indicator is a counter of aberrant points in the whitened vibratory signal.

Abstract: The invention relates to an acquisition module for a monitoring system of a rotating machine, in particular of an aircraft engine, the acquisition module comprising at least one measurement sensor for measuring an analogue signal x(t) of a physical quantity of a member of the rotating machine, at least one sample-and-hold device configured to collect a sample of the analogue signal x(t) at sampling times t n and to maintain it constant between two sampling times t n, and at least one memory for storing samples, the sample-and-hold device being configured to collect a sample of the analogue signal x(t) at sampling times t n defined in a random manner, the sampling times t n being defined according to the following law t n=n? t+? n, the samples and the sampling times t n being stored in the memory.

Abstract: The invention concerns a method for monitoring a gear system (1) comprising at least two wheels, each wheel having a characteristic frequency (f1, f2), a vibratory or acoustic signal representative of these vibrations having been acquired by a sensor (21), a vibratory or acoustic digital signal x(t) having been obtained, the method comprising, for each characteristic frequency of the system (1), the steps of filtering (E1) the digital signal by means of a filter in such a way as to obtain an image monitoring signal of at least one vibratory component of at least one defect; determining (E3) the square envelope of said monitoring signal, defined by the square absolute value of the Hilbert transform of the monitoring signal so as to extract an image of the modulating signals associated with the rotation of the wheels from the monitoring signal; determining (E4) the synchronous average of said square envelope relative to the period of rotation of a wheel of interest chosen from the wheels of the gear, said avera

Abstract: The invention relates to an acquisition module for a monitoring system of a rotating machine, in particular of an aircraft engine, the acquisition module comprising at least one measurement sensor for measuring an analogue signal x(t) of a physical quantity of a member of the rotating machine, at least one sample-and-hold device configured to collect a sample of the analogue signal x(t) at sampling times t n and to maintain it constant between two sampling times t n, and at least one memory for storing samples, the sample-and-hold device being configured to collect a sample of the analogue signal x(t) at sampling times t n defined in a random manner, the sampling times t n being defined according to the following law t n=n? t+? n, the samples and the sampling times t n being stored in the memory.

Abstract: A method includes obtaining a vibration signal acquired by an accelerometer sensor; eliminating a deterministic component of the vibration signal; obtaining, for a determined defect, a characteristic theoretical frequency of this defect and a determined maximum deviation around this theoretical frequency; computing, as a function of a cyclic frequency, an integrated cyclic coherence of the processed vibration signal; estimating an actual frequency of the defect on the basis of the integrated cyclic coherence, of the theoretical frequency of the defect and of the maximum deviation; computing a diagnostic indicator of the defect by summing M integrated cyclic coherences of the vibration signal evaluated as M cyclic frequencies respectively equal to M harmonics of the estimated actual frequency of the defect; comparing the diagnostic indicator of the defect with a predetermined threshold, and in the event of it being exceeded, detecting the defect on the bearing.

Abstract: A method of searching for a defect capable of affecting a rotating mechanical power transmission device includes a step of obtaining a signal s that can be modeled by a product of a high frequency signal s1 and a low frequency signal s2, generated by the rotating mechanical power transmission device and acquired by a sensor, a step of determining estimates of the signals s1 and s2, minimizing a difference between all or part of the signal s and a product of these estimates, a step of analyzing the estimates of the signals s1 and s2 in order to detect the presence of a defect affecting the rotating power transmission mechanical device, and, if a defect is detected, a step of locating said defect from at least one of the estimates of the signals s1 and s2.

Abstract: A method detects a defect in a vibration sensor including the whitening of the vibratory signal delivered by the vibration sensor, and the calculation of an indicator of asymmetry of the whitened vibratory signal. The whitening may be a cepstral whitening implemented simply by dividing the Fourier transform of the signal by its modulus. The asymmetry indicator is a counter of aberrant points in the whitened vibratory signal.