How to

See which frequencies a signal contains

Use the spectrum to find a signal's frequencies, harmonics and noise.

  1. Start the signal and press Run.

  2. Under Display, choose Split to see the trace and its spectrum, or Spectrum to give the spectrum the whole screen. Keyboard: F.

  3. Rest the pointer on a peak, or tap it on a phone, to read its frequency and level.

  4. The measurements give the strongest frequency (Spectrum peak) and its level.

  5. To look closer, turn the mouse wheel over the part of the spectrum you want, or use Span and Centre frequency under Spectrum. Full span shows everything again.

  6. For audio, choose a Log frequency axis. To match other equipment, choose the Level unit it uses.

  7. To find a small tone in noise, choose Average under Trace. To catch a tone that comes and goes, choose Max hold.

  8. To compare two tones, turn on Markers, press A to peak, and place B on the other tone. The measurements give the difference. Peak table lists the strongest tones at once.

  9. To watch a frequency change over time, choose Spectrogram under Display.

  10. To see the spectrum of one part of a capture, such as a burst, place the Cursors around it and press Gate to cursors.

Every key is described in Spectrum.

What to look for is explained in What a spectrum shows.