Fig. 1From: Ultra-short term HRV features as surrogates of short term HRV: a case study on mental stress detection in real lifeHRV processing workflow. ECG: Electrocardiogram; NN/RR is the ratio of the total RR intervals labelled as NN (normal-to-normal beats); short term: HRV is analyzed in 5 min excerpts; ultra-short term: HRV is analyzed in excerpts of 3, 2, 1 and 0.5 min lengthBack to article page