In Reply to: Peak & Correlation Detectors posted by Tyler on 08/26/03 at 10:56 AM:
For a peak detector schematic, see figure 7 in National Semiconductors application note: AN-4.
In order to make a correlation detector, you have to know what type of signal you are trying to correlate (sine, triangle, square, or other waveform). The detector would incorporate a phase lock loop and an oscillator that produced a waveform that would correlate with the signal. I don't think any correlation detector would be simple.