Cable and Antenna Analyzer Measurement Guide : Cable and Antenna Analyzer : Trace
Pressing the Shift key and the Trace (5) key brings up the Trace main menu. The trace math menu inside the cable and antenna analyzer supports Trace Overlay features to allow viewing a two traces at the same time. This is useful when comparing a stored trace to a live trace. Trace Math operations include Trace – Memory, Trace + Memory, and
(Trace + Memory)/2. It is possible to copy a trace to display memory directly from the trace math menu. Traces can also be downloaded from Line Sweep Tools or Master Software Tools into the instrument and compared with live traces.
The examples below illustrate how the trace overlay feature can be used to compare a trace stored in memory with a live trace.
Trace Overlay
This example shows two traces without any trace math applied.
1. Press Shift and Trace (5) to enter the Trace Menu.
2. Press Recall Trace and locate the appropriate trace from the recall menu.
3. Press the Trace Overlay On/Off key to turn it on. The white trace is the recalled from memory trace and current trace is yellow.
Trace Overlay of Two Traces
Trace Math Example
The example below illustrates how the Trace - Memory feature can be used to compare the phases of two cables.
1. Press Shift and Trace (5) to enter the Trace menu.
2. Press Trace Overlay to turn off (underscore) trace overlay.
3. Perform a trace on a device under test (Cable A) and save it by pressing the Copy Trace To Display Memory key.
4. Perform a second trace on a device under test (Cable B).
5. Press the Trace - Memory key to view the difference between Cable A and Cable B.
Trace-Memory Used to Compare the Phases to Two Cables
Refer to Trace Menu for additional information.
(Trace+Memory)/2 Trace Math Example
This math function is most useful when measuring one-port Cable Loss (using Cable Loss measurement function of the Cable and Antenna Analyzer).
Use the Open/Short tools from the calibration kit for best results.
Because the Short and Open traces are 180° out of phase with each other, the ripples created by each trace will cancel out when using this math function, resulting in a more accurate cable loss measurement.
1. Connect the Short to the end of the cable (DUT) and store the resulting trace into memory.
Trace with Short at end of DUT cable
2. Remove the Short and connect the Open to the end of the cable (DUT). You should see a similar amount of ripple but it will be 180° out of phase with the previous trace.
Trace with Open at end of DUT cable
3. Use the Trace Overlay feature to see both responses.
Comparison of Short and Open traces using Trace Overlay function.
4. Apply the (Trace + Memory)/2 trace-math function, which will reduce or eliminate the ripple resulting in a more accurate Cable Loss measurement.
Trace with (Trace + Memory)/2 trace-math function applied