Update Stimulus Definition (Channel Quality)

The Update Stimulus Definition expanding parameter group updates the definition of tones from predefined settings or from the tones used in the current measurement.

The multitone stimulus definition can be viewed in the Stimulus Definition trace.

Predefined defines stimulus tones based on Amplitude and Phase.

Amplitude specifies the amplitude of all tones (currently fixed at a constant 0 dB).

Phase specifies the phase of the multitone stimulus to apply to the tones.

Constant: Constant (0 deg) phase for all tones.

Parabolic: Parabolic phase across the tones (chirp-like)

Random: Random phase (OFDM Orthogonal Frequency Division Multiplexing: OFDM employs multiple overlapping radio frequency carriers, each operating at a carefully chosen frequency that is Orthogonal to the others, to produce a transmission scheme that supports higher bit rates due to parallel channel operation. OFDM is an alternative tranmission scheme to DSSS and FHSS.-like)

Update updates the stimulus tone definition according to the settings.

From Current Measurement updates the definition of tones based on the current multitone measurement. The Active/Inactive, Detection Threshold, Magnitude and Phase properties determine what properties of the tone definitions are updated. This is useful when evaluating different tone notching scenarios with a common multitone signal definition, or when switching between multiple multitone signal definitions (if the precise reference of the original signal is not required for the measurement task). This may also be useful for correcting the stimulus signal reference for impairments in the signal generator or fixturing prior to the desired measurement plane. This may significantly simplify making relative channel quality measurements (like group delay, phase linearity, or magnitude linearity).

This feature is not available when Compute Unbalanced is enabled.

Active/Inactive determines which tones in the current definition are active or inactive based on the current measurements and the value of Detection Threshold.

Detection Threshold specifies the tone power level (relative to peak tone power level) to consider a tone as active when auto-detecting tone active/inactive status from the measured waveform (Update operation).

When Auto is selected, the measurement tries to automatically detect the enabled/disabled state of tones when an Update operation is performed. If selected, the variance of measured tone magnitude will determine how the update stimulus from response operation decides active or inactive state of each tone. If not selected, the Detection Threshold is used instead. When Active/Inactive parameter is not selected, this value is ignored by the update stimulus from response operation and the GUI control is disabled.

Magnitude replaces the magnitude of all tones in the multitone definition to reflect the current measurement results.

Phase replaces the phase of all tones in the multitone definition to reflect the current measurement results.

Update updates the stimulus tone definition according to the settings.