peakhold

Peakhold is a feature in electronic measurement equipment that records and retains the maximum amplitude observed in a signal during a measurement interval. It allows users to observe high-amplitude transients that may be missed by averaging or instantaneous readings.

In operation, the input signal is continually sampled. A peak-hold circuit or digital algorithm stores the largest sample seen within the current window and keeps that value displayed or read out. The held peak remains available even after the instantaneous signal falls below it; the hold may be cleared manually or after a set time, or may be reset at the start of a new measurement.

Applications include capturing short spikes in signals, peak voltages in power electronics, RF pulse measurements, audio testing, and any scenario where transient excursions matter.

Variants and related concepts include peak hold being related to peak detect and envelope detection. Some instruments provide multiple channels or adjustable hold time; others offer indefinite hold until cleared.

Limitations include accuracy depending on sampling rate, aperture time, and memory depth. Very fast, narrow transients can be missed if sampling is insufficient. Some implementations include decay or droop, causing the stored peak to slowly decrease over time.

History notes that peak-hold functionality evolved from analog peak detectors in oscilloscopes and became standard in digital instruments, with refinements in accuracy and reset control.

See also: oscilloscope, peak detector, hold mode, sample and hold.