Averaging and signal analysis. Because of the small amplitude of the PERG, signal averaging is always necessary. The amplifiers must return to baseline rapidly following artifactual signals to avoid inadvertent storage of non-physiological data. Data display systems. Display systems must have adequate resolution to represent accurately the characteristics of this small amplitude signal.
Optimal conditions allow for simultaneous display of input signal and average.
In the absence of a simultaneous display, the system should allow a rapid alternation between input signal display and average display. Thus the quality of the input signal can adequately be monitored. Even with a computerised artifact rejection system, it is important that the input signal be monitored for baseline stability and the absence of amplifier blocking. Clinical Protocol Preparation of the Patient Positioning. The patient should be positioned as comfortable as possible and leaning against a head-rest.