Lambda SR1, Operation Manual, Page: 265 / 317

SR1 Operation 265
© 2014 Stanford Research Systems
2.8.7 Distortion Panel
The Distortion Quick Measurement panel offers fast access to three distortion-related measurements.
THD, Individual Harmonic Amplitude, and an FFT of distortion. THD, measured using the THD Analyzer ,
expresses the sum of all harmonically related distortion products either as an absolute level or as a ratio
to the fundamental. Individual Harmonic Amplitude (Selected in the Analysis window by choosing
"Harmonics") displays the amplitude of each individual harmonic as a function of harmonic number.
Finally, the Distortion FFT uses the time-domain detector and FFT analyzer in tandem to examine the
frequency spectrum of the EUT output with the fundamental notched out.
Cabling Configuration
The output of SR1's analog or digital generator is connected to the EUT's input. The output of the EUT is
connected to SR1's analog or digital inputs. The number of inputs and outputs and the connectors used
are specified in the
Setup Panel .
Generator Configuration
The output waveform is set to Sine or Low-Distortion Sine. For free-run operation the amplitude of the
generator is set to the value in the "start" column of the panel. For swept operation the amplitude is
swept from the start to stop value with the number of steps specified.
Analyzer Configuration
The analyzer configuration depends on the the Analysis selected. For THD or individual Harmonic
Amplitude, one or both analyzers are configured as THD analyzers depending on the number of output
channels selected in the setup panel. For this analysis the default is to select all harmonics to be
included in the THD measurement. If individual harmonic measurement is required the change must be
manually made on the THD analyzer panel.
For Distortion FFT, A0 is set as a Time Domain Detector and A1 is setup as an FFT analyzer. Note that
in this configuration only one channel can be analyzed at a time. (Channel A is the default) In order to
analyze channel B, the source for the A0 analyzer must be manually changed to "Analog B," or press
sweep with no freq or level steps. (This will essentially perform a free-run measurement on both