Stanford Research Systems SR780, Operating Manual And Programming Reference

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4-44 Harmonic Marker Menu
SR780 Network Signal Analyzer
The small square marker will move to the selected harmonic or sideband. If the selection
is not within the measurement span, the marker will move to the highest or lowest
measured frequency (which will be reported as the Marker Position).
Each display has its own Harmonic and Sideband Display. This entry field can be linked
to both displays using the [Link] key.
Command: HDSP (?) d {, i}
Readout Mode
Select the Readout Mode for the Harmonic and Sideband Marker of the active display
[Absolute, Relative]. The Marker Position Display shows the amplitude of the
Fundamental or any identified Harmonic or Sideband in either Absolute units or Relative
to the fundamental.
Relative Mode reports the amplitude of the selected harmonic or sideband relative to the
fundamental. The marker amplitude units are dBFundamental. The frequency is always
absolute.
Each display has its own Readout Mode. This entry field can be linked to both displays
using the [Link] key.
Command: HRDO (?) d {, i}
THD
This menu box displays the Total Harmonic Distortion (THD) of the active display. The
THD squared is the harmonic power (sum of the squared magnitudes of the harmonics)
divided by the sum of the fundamental power plus the harmonic power.
Only those harmonics within the measurement span which are identified by Harmonic
Markers contribute to the THD.
The THD is displayed in dB (20log(THD) )and percent.
To measure THD+N, use the Band Marker.
Command: HTHD ? d , i
Harmonic Power
This menu box displays the Total Harmonic Power of the active display. The harmonic
power is the sum of the squared magnitudes of the harmonics identified with a Harmonic
Marker. The result is shown in Vrms. To convert to power, square this result.
Command: HPWR ? d