Peak Detect allows you to maximize the signal sampling rate in order to capture fast events, such as spikes, glitches and other anomalies, that may normally be undetected.
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Peak Detect Icons (Typical) |
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On (Sampling maximized) |
Off (Sampling not maximized) |
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Peak Detect Off
When peak detect is off, the scope samples at a high rate but saves just enough sample points to the data buffer memory to plot a waveform across the screen. No preference is given to any point during the selection process.
— Turning peak detect “off” is suitable for basic measurements, and viewing waveforms (e.g. oxygen (O2) or Cam sensor) when capturing fast events is not necessary.
— The longer the time sweep, the greater the chance a glitch could be missed because it occurred in between the sample points saved to the data buffer memory. To increase the chance of capturing a glitch with peak detect “off”, a shorter time sweep should be selected.
— Turning peak detect “off” avoids the need for an external filter to decrease the display of unwanted noise, which can make diagnosis more difficult.
Example: With a time sweep of 10 seconds on a screen 100 points wide, the effective sample rate would be 10 times a second. Decreasing the time sweep to 1 second, increases the effective sample rate to 100 times a second. At this time setting, a fast occurring event is more likely to be captured due to the increased rate. This is the standard mode of operation for many scopes.
Peak Detect On
When peak detect is “on”, all sample points are evaluated. The points stored to the data buffer memory are intelligently selected to capture fast events that might be missed at slower effective sample rates. Peak Detect captures fast events, spikes and glitches for signals going in both positive and negative directions.
— Turn peak detect "on" when capturing fast events (e.g. ignition firing voltage, glitches, and intermittent events).
— Turning peak detect “on” may capture unwanted noise, therefore, using peak detect may not be suitable for some tests (e.g. oxygen (O2) sensor), as the waveform may be more difficult to evaluate due to the additional noise that may be displayed.
— Peak Detect decreases the possibility of waveform aliasing.