Configure a Reference IN Signal  for Multi-modules(M98xxA, P50xxA/B)

When you use the reference signal in the multi-module configuration, normally the signal should be input into the Ref In port on the most left module. The reference signal is distributed to the other modules through the control cables. However, this configuration will degrade the reference clock stability and causes worse phase stability in some applications. This function can improve the reference clock stability by distributing the reference signals directly to each module. This improves the wave parameter’s phase stability, and multi-source’s phase control stability in Differential I/Q measurement. Use 100 MHz signal for this configuration instead of 10 MHz.

Ref. In signal connection example of M9808A 4-modules (8-port) case

How to change Ref IN configuration

Use one of the following methods to change the Reference IN configuration.

Using Hardkey/SoftTab/Softkey

Using a mouse

  1. Press Macro > Macro1 > Ref. In Config

  1. Click Utility > Macro  > Ref. In Config [m980xrefincon...]

 

M980x Ref. In Configuration dialog box help

Normal: Int. Ref or Ext Ref to 1st Module:(Default) Use the reference signal on the Ref In port of the most left module. Int./Ext. Ref.In setting can be changed by SCPI command/Soft Key.  

Adv.: 100 MHz Ext. Ref to each modules. MCX: Use the 100 MHz reference signals on the Ref In port of each module in order to improve the reference clock stability in the multi module configuration. Set the reference signal frequency at 100 MHz by the SENSe:ROSCillator:EXTernal:FREQuency command.

After clicking OK, the dialog box is displayed, then firmware will be restarted to change the configuration.  

 

Limitation

  • 100 MHz signal to Ref.In must be provided before the firmware is executed. When 100 MHz Ref. In is not detected at the firmware startup, the error message will be displayed.

  • Calsets will be not valid once you exit the firmware. It is highly recommended to perform the calibration after firmware restart.

  • Int./Ext. Ref.In settings can not be changed in the Adv. mode.