Baseband I+jQ Measurement

The 89600 VSA - BBIQ Baseband I+jQ measurement solution only applies to X-series analyzers that have Option BBA Analog Baseband I/Q Inputs installed.

This topic provides the Baseband I+jQ Measurement configuration, setup, and measurement procedure to successfully make baseband two-channel ( i+jQ) measurements using the 89600 VSA with an Keysight X-Series Signal Analyzer with option BBA. BBIQ is a two-input measurement where the I and Q input waveforms are configured as I+jQ and then analyzed as a configured I+jQ channel. In BBIQ measurements, the span of the configured signal is double the span of the I and Q signals from the individual inputs.

A signal overload on either of the two channels causes the VSA software to display an overload condition on both channel traces. This condition caused by the mixing of the signals to create the BBIQ measurement and is not a fault of the hardware or software.

The MXA BBIQ measurement supports all the basic VSA time, frequency, and statistical measurements as well as analog demod, flexible digital demod, and the supported standard-specific demod measurements. Additionally, BBIQ supports two-channel measurements such as frequency response, cross-correlation, and coherence.

Custom Input Channel Configurations: When using the Input Channel Configuration dialog to specify or modify the input channel configuration mapping, only the VSA default set of channel configuration mappings are allowed; "invalid" channel configuration mappings are disallowed and the "OK" button is disabled "greyed out".

BBIQ "Baseband I+jQ" Measurement Procedure

This procedure applies to both the Remote and Embedded configurations. Not all steps apply to both configurations; differences are noted.

Install and Configure the 89600 VSA software, the hardware, and I/O interfaces.
- Embedded configuration only
  For embedded configuration, go to the Embedded Configuration topic.
- Remote configuration only
  For the Remote configuration instructions, see the Remote Configuration topic.
  The Remote configuration only supports a LAN Local Area Network: A communications network that serves users within a local geographical area, typically over distances of around 100m. Wireless LANs use wireless communicaitons to network devices so there is no need for data cabling. interface.
Start the 89600 VSA application
- Embedded configuration only.
  For the Embedded configuration, the 89600 VSA application is started by selecting the 89601 VSA mode in the analyzer.
  Using the 89600 VSA in the Embedded configuration is different than using the VSA running in a PC. Refer to "Running the 89600 VSA Application" in the Embedded Configuration topic to learn how to run, use, and exit the 89600 VSA running inside the analyzer.
- Remote configuration only
  
  For the Remote configuration, click Start > Keysight 89600 Software <ReleaseVersion> > Keysight 89600 VSA <ReleaseVersion>.
  
  Front Panel Control
  
  The 89600 VSA software locks-out manual control of the analyzer front-panel while it is running. To get manual control of the analyzer front-panel, disconnect the 89600 VSA measurement -- select Control > Disconnect. Disconnect will pause the measurement and release control of the analyzer. The analyzer can now be used independently from 89600 VSA. When the 89600 VSA measurement is resumed, the analyzer setup is restored to the pre-disconnect state.
Configure the 89600 VSA to use real hardware.

The analyzer may start in simulation mode, make sure the analyzer is configured to real hardware mode.

Click Utilities > Hardware > Configuration and check that real hardware is being used.
Select and Configure the Keysight X-Series Signal Analyzer as primary and secondary hardware modules.
1. Open the New Hardware Configuration dialog box (Utilities > Hardware > Configurations > Add button). Select the X-series Signal Analyzer from the list of Possible Logical Instrument and drag it to the Configuration window. This will be the primary analyzer.
2. Select X-series analyzer a second time from the list of Possible Logical Instrument and drag it to the Configuration window. This will be the secondary analyzer.
3. In step 2 of the New Hardware Configuration dialog box, select the specific X-series analyzer to be used for each of the Logical Instruments in this configuration.
4. In step 3, name the configuration.
5. Click OK.
6. Select this Analyzer Configuration as the Current Analyzer Configuration in the Configurations tab.
Configure the Hardware parameters.

Input Extension parameters that are unique to 89600/X-Series hardware systems are listed in the Input Extensions (Keysight X-Series Signal Analyzer) topic.
Configure the Measurement Setup parameters.

The Measurement Setup parameters that are unique to using the X-series Signal Analyzers with the 89600 VSA software are listed in the Measurement Setup Parameters topic.
Input Range Overload Condition

For 2-Ch Baseband measurement configurations, out-of-band input signals will cause an unexpected ADC Analog-to-Digital Converter Overload condition, ("OV" trace indicator) when the following conditions occur:
1. The Out-of-Band signal frequency "f_o" is greater than the current VSA measurement bandwidth (20 MHz Megahertz: A unit of frequency equal to one million hertz or cycles per second. maximum) but less than the maximum hardware analog input channel bandwidth (40 MHz). Therefore: VSA BW < f_o < 40 Mhz.
2. Out-of-Band signals are combined with the VSA Measurement In-Band signals to determine the range level. An unexpected range overload will occur when the additional Out-of-Band signals cause the combined VSA measurement range level to exceed the current VSA measurement Range setting.
  This Range Overload condition may seem unexpected because the Out-of-Band signals are not shown on the VSA Trace window hiding the over range signals from view.
Calibrating the Analyzer

Before making a measurement, the analyzer should be calibrated, or aligned, to increase the measurement accuracy. See the Alignment/Calibration help in the Measurement Setup topic.
Setting the Input Channels

Click Input > Channels >I+jQ (Ch1+j*Ch2)

Selecting this input setting switches the hardware to baseband and sets the VSA software to combine the signals for I+jQ measurement. These conditions are displayed on the trace titles.