Abstract: Anticipation signals are derived for each peak whenever a differential exists within a closed loop having the electrical output connected to the input thereof and a confirmation signal is derived after each peak at a threshold level of the new slope polarity exceeding the noise level of the electrical output. The amplitude of each peak is stored as a voltage level which follows the electrical output throughout either slope polarity until a peak is reached and this voltage level is continuously compared with the electrical output to derive the slope polarity thresholds. Otherwise, a very particular embodiment is disclosed with which the stored voltage level only relates to either the most significant maximum or minimum peak of the electrical output and the disclosed embodiments are related to instruments which perform spectral analysis.