Fig. 4
From: Fast time-varying linear filters for suppression of baseline drift in electrocardiographic signals

Schematic representation of direct realization of the LP filter with minimum delay. Buffer A buffer of RR intervals (N max length), buffer B buffer of the input signal samples (2N max − 1 length), filter a filter with impulse response h(n) = {1, 2, 3,…, N,…, 3, 2, 1}, N RR number of sampling intervals, N RRmax number of samples of the longest expected RR interval, x(n) current input sample