How to convert Skin Conductance Level (SCL) to Skin Conductance Response (SCR) using LabChart?

The FE116 GSR Amp is a fully isolated Galvanic Skin Response amplifier with low voltage, 75 Hz AC excitation and automatic zeroing. The low-voltage AC excitation reduces the electrode polarization artifacts found in DC systems. The amplifier itself is a DC amplifier (otherwise the traces we measure would not remain at a certain conductance level – and also why we need to zero it). As a result the Skin Conductance Level (SCL) is recorded. By adding a high pass filter to the system one measures that a response has occurred and by how much, then the signal returns to zero, until the next response.
However, the resulting amplitude is rather small and the trace gets a negative and positive peak. 
Based on a original recording using a commercially available Skin Conductance Meter the following Arithmetics results in a comparable trace:
Smoothsec(Differentiate(RClowpass(ch1, 0.205), 3), 1.3), where ch1 is the recorded SCL.

For a comparison please have a look at the attached file
ch1: SCL signal recorded using a Skin Conductance Meter
ch2: SCR signal recorded using a Skin Conductance Meter 
ch3: SCR based on ch1 using the above arithmetics
ch4: SCR based on ch1 using a high pass filter