Last Week's Question

Quasi-peak values are always,

  1. equal-to or less-than peak values
  2. equal-to or less-than average values
  3. both "a" and "b"
  4. none of the above


The correct answer is "a". Quasi-peak values are always less than or equal to peak values. For continuous signals (i.e. signals that exhibit constant power at the frequency being evaluated), the quasi-peak value is equal to the peak value. For intermittent signals, the quasi-peak detector records a value that rises when the signal is present and falls when the signal is absent. The rise time is defined by a time constant known as the "attack time constant." The fall time is defined by a "decay time constant". The quasi-peak value is the average value of this rising and falling power level. The CISPR quasi-peak detector (0.15 - 30 MHz) has an attack time constant of 1 ms and a decay time constant of 160 ms.

Plot of Peak, Quasi-Peak and Average Values

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