118                                                                                                                     Keysight N9927-90001 User’s Guide
Time Domain – Option 010
Gating
Gating
Perhaps the most beneficial feature of Time Domain transform is the Gating 
function. When viewing the Time Domain response of a device, the gating 
function can be used to “virtually” remove undesired responses.  You can then 
simultaneously view a frequency domain trace as if the undesired response did 
not exist. This allows you to characterize devices without the effects of external 
devices such as connectors or adapters. 
Gating is best performed while viewing a Time Domain trace. Then, either 
disable Transform, or separately view a frequency domain trace to see the 
trace with the gated effects removed. 
The following image shows how gating can affect measurement results. 
All 4 traces show the same S11 measurement.
Trace 1 shows the frequency response without gating enabled.
Trace 2 shows the transform response without gating enabled.
Trace 3 shows the transform response with gating enabled.
When a discontinuity in a test device reflects energy, that energy will not 
reach subsequent discontinuities. This can “MASK”, or hide, the true 
response which would have occurred if the previous discontinuity were not 
present. The Gating feature does NOT compensate for this.