A filtering device receives a pressure signal (P) from a pressure sensor in a fluid containing system, the pressure signal (P) comprising first pulses originating from a first periodic pulse generator and second pulses. The device acquires a reference signal which is indicative of a current operating frequency of the first periodic pulse generator. The device identifies, based on the reference signal, a plurality of harmonics (v1 - v8) associated with the current operating frequency, computes correlation values (λ̂1 - λ̂8) between the harmonics and the pressure signal (P) within a time window in the pressure signal (P), and generates a filtered signal by subtracting, as a function of the correlation values (λ̂1 - λ̂8), the harmonics from the pressure signal (P). The use of correlation values is a direct, fast, robust and computation-efficient approach for estimating the signal contribution ( d̂ ) from first pulses in the pressure signal (P).
