2-Port Transmission Measurement Guide : 2-port Transmission Measurement (Option 21) : Trace
 
Trace
Pressing the Shift key and then Trace (5) key brings up the Trace main menu. The trace math feature supports Trace Overlay to allow viewing two traces at the same time to compare a stored trace to a live trace.
Trace Math operations include Trace - Memory. It is possible to copy a trace to display memory directly from the Trace menu. Traces can also be recalled from internal memory or downloaded from Master Software Tools into the instrument and compared with live traces.
Trace Overlay
The example below illustrates how the trace overlay feature can be used to compare a trace stored in memory with a live trace.
1. Press Shift then Trace (5) to enter the Trace Menu.
2. Press Recall Trace and locate the appropriate trace from the recall menu.
Note 
Refer to the User Guide for additional information on the Trace menu.
3. Press the Trace Overlay View/Blank key to turn trace overlay On.
The green trace is the recalled trace from memory, the current trace is yellow.
Trace Overlay of Transmit and Receive Band of a Tower Mounted Amplifier