Using Channel Sounding for Reference Plane Calibration

To ensure a proper channel frequency response measurement for the purpose of calibrating the reference plane in loopback (source connected to receiver):

Generate a signal in N7608C Signal Studio Pro for Custom Modulation
1. Set Symbol Rate to the bandwidth you wish to calibrate.
2. Select the Flat filter.
3. Download to source.
Configure the VSA
1. Switch to the Channel Sounding measurement type and open the Channel Sounding Properties dialog.
2. Click the Preset button in the Format tab.
3. Change Rx Filter to None.
4. Set Sequence Length and Symbol Rate to match the settings in Signal Studio.
5. Run the measurement and verify that you see the signal in the Spectrum trace.
6. Adjust Input > Analog > Range to lowest before overload. Note that the channel measured can change slightly with different instrument range values. If possible, choosing the same range as future measurements will provide the best results.
7. Observe SymClockErr. Use this value in the Advanced tab > Symbol Clock Adjustment. Note that you can increase Number of Repeats to stabilize the SymClockErr estimate.
8. Show the Eq Ch Frequency Response trace (Trace > Data > Sounding > Channeln > Eq Ch Frequency Response).
9. Pause the measurement.
10. Select the Eq Ch Frequency Response trace and copy it to a register (File > Copy Trace...)
11. Open Input > User Correction and enable Fixed Equalization for the corresponding measurement channel index. Select the data register that the trace was copied to in the previous step.

You should now see that the Channel Sounding measurement frequency response is flat.