254

|

6 Applications and Methods in Biosignal Processing

ECG

band pass

derivation

sqaring

MA-filter

time t / s

Fig. 6.27: Output signals of the individual blocks in Figure 6.22 according to the Pan-Tompkins-

algorithm.

values SPKI and NPKI, which are calculated according to

SPKI = 0.125 ⋅PEAKI + 0.875 ⋅SPKI

at signal peak

NPKI = 0.125 ⋅PEAKI + 0.875 ⋅NPKI

at Noise Peak

adaptively. The thresholds are modified as follows:

THRESHOLD_I1 = NPKI + 0.25 ⋅(SPKI −NPKI)

THRESHOLD_I2 = 0.5 ⋅THRESHOLD_I1 .

If another QRS complex was actually found during the backward search initiated

by exceeding the second threshold, the estimated value of the QRS complex SPKI

is further corrected:

SPKI = 0.25 ⋅PEAKI + 0.75 ⋅SPKI .