EMC Question of the Week: December 2, 2019

Spectrum Analyzer Display

At the third harmonic, the quasi-peak value of the radiated emissions from a 25-MHz clock (square wave) source is

  1. equal to the peak value
  2. 3 dB lower than the peak value
  3. 6 dB lower than the peak value
  4. 6 dB higher than the peak value

Answer

The best answer is "a". As long as the signal power is constant during the measurement, peak and quasi-peak values are the same. It doesn’t matter what the waveform looks like or which harmonic is measured.

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