def get_pulse_s(self):
        """Get pulse duration in seconds, for pulsed measurements."""
        
        try:
            dwelltime = self.ppg.dwelltime.mean
            beam_on = self.ppg.beam_on.mean
        except AttributeError:
            raise AttributeError("Missing logged ppg parameter: dwelltime "+\
                    "or beam_on")
        return dwelltime*beam_on/1000.
Get pulse duration in seconds, for pulsed measurements.