General Settings (Signal Analyzer)

The PXB uses the signal analyzer as a down converter for RF-to-RF in the PXB's external input (ext in) configurations. The PXB controls the signal analyzer only in the signal analyzer's IQ Analyzer (Basic) mode. The PXB sets the signal analyzer to a known state, so only the signal analyzer settings displayed in the PXB user interface are safe to change. Making other signal analyzer setting changes may be coupled with the known state of the signal analyzer as the PXB attempts to control it and could deliver undesirable results.

When a configuration that uses a signal analyzer is loaded or recalled, the PXB attempts to establish communication with the signal analyzer when the configuration is loaded. If communication is not established with the signal analyzer at that time, the PXB will attempt to establish communication:

When the PXB establishes communication with the signal analyzer, the PXB:

  1. Sets the signal analyzer to the IQ Analyzer (Basic) mode

  2. Performs a Mode Preset on the analyzer

  3. Downloads its Signal Analyzer user interface settings to the analyzer


 

Programming Control of the Signal Analyzer

The PXB controls the signal analyzer only through its user interface, so controlling the signal analyzer programmatically must be done directly. Refer to the signal analyzer's programming guide for details.

When a configuration is loaded or recalled, the PXB presets the signal analyzer and then sets it to IQ Analyzer (Basic) mode. So, when the system is being controlled programmatically, perform the tasks in the order listed.

  1. Connect the signal analyzer to the PXB.

  2. Load or recall the configuration.

  3. Send any SCPI commands that would change the signal analyzer.

Following these steps in this order ensures that the PXB does not overwrite any SCPI commands sent to the signal analyzer.

Optimizing the MXA provides a procedure and discussion of how to maximize the MXA's dynamic range for use as an input to the PXB. 

Basic

Center Frequency

Range: Depends on the Signal Analyzer Frequency Option
Default: 1 GHz
Resolution: 1 Hz

Sets the frequency that corresponds to the horizontal center of the graticule. While adjusting the Center Frequency, the Span is held constant, which means that both Start Frequency and Stop Frequency will change.

 

Reference Level

Range: Log Scale: –170 to +30 dBm
Default: 0.00 dBm
Resolution: 0.01 dB

controls the vertical (y-axis) placement of the signal on the signal analyzer display. The reference level is the amplitude power or voltage represented by the top graticule on the display. Changing the value of the reference level changes the absolute amplitude level of the top graticule line. Setting the reference level to a value slightly above the expected maximum power level of the signal analyzer's input signal provides optimum results.

 

Return to top

 

Mechanical Attenuation

Range: 0 to 70 dB
Default: 10 dB
Resolution: 2 dB

Sets the mechanical attenuation value to pre-adjust the input signal for minimum clipping. This attenuates the input so it does not over-drive the analyzer (thus preventing IF overload). For more information, refer to N9060A IQ Analyzer Mode User's and Programmer's Reference (N9060-90018).


 

Setting of the signal analyzer input attenuation to the correct level is critical. The input attenuation should be set to the minimum possible without over driving the analog-to-digital converter (ADC). When the ADC is over driven, the signal is clipped and distorted by the MXA before it arrives at the PXB.

 

Enable Electrical Attenuation

Choices: On, Off
Default: On

Turns the electrical attenuation on or off. When Electrical Attenuation is enabled, the following transitions occur:

 

Electrical Attenuation

Range: 0 to 24 dB
Default: 0 dB
Resolution: 1 dB
Dependency: Available when Enable Electrical Attenuation is set to On

Sets the electrical attenuator value in dB. If Electronic Attenuation is enabled, then the stop frequency of the analyzer is limited to 3.6 GHz and the internal preamp is unavailable, that is, the start frequency, the stop frequency, the center frequency, and span values are all limited to a maximum of 3.6 GHz plus the frequency offset.

For more information on the electrical attenuator functionality, refer to N9060A IQ Analyzer Mode User's and Programmer's Reference (N9060-90018).

 

Return to top

 

Preamp

Choices: Off, Low Band, Full Range
Default: Off
Dependency: Available when Enable Electrical Attenuation is set to Off. Not available on all hardware platforms 

Controls the signal analyzer's internal preamps. Turning on the preamp gives a better noise figure, but a poorer dynamic range. You can optimize this setting for your particular measurement.

For more information on the preamp functionality, refer to N9060A IQ Analyzer Mode User's and Programmer's Reference (N9060-90018).

IF Gain

Choices: Autorange, Low, High
Default: Autorange
Dependency: Your signal analyzer must be in IQ Analyzer (Basic) mode to use this setting

Allows optimization of IF gain for specific signals or signal levels. Use Autorange as a general-purpose setting. Low is best for large signals. High gives the best noise level.     

Enable Leveling During Power Cal

Choices: On, Off
Default: On
Dependency: Available when Enable Electrical Attenuation is set to On

Enables signal analyzer input leveling during Power Cal by adjusting input attenuation, maximizing the signal level to the ADC for best performance. Leveling is automatically done by reducing input attenuation until an ADC over-range is detected, then increasing attenuation 2 dB. Does not automatically control IF Gain or Preamp.

In general:

 

Return to top