Real Time

Configuring the PXB

In order to generate the test signals, the PXB uses and controls signal generators as RF upconvertors. Within the PXB Setting window, there is the requirement to set some settings for the signal generators so that they can be used with the PXB.

If more information is needed other than what is contained in this procedure or in the software hints for each of the fields, refer to the PXB online documentation.

1. Ensure that software is connected to the PXB—within the tree window, the PXB connection shows PXB (Connected).

   If it is not connected (PXB (Disconnected)), refer to the Testing Connections topic to make the connection.

2. Click on the desired test to see the number of required test signals.

   Typically the PXB requires a signal generator connection for each signal. But some tests such as for LTE Clause 7, where all of the signals can be combined into a single waveform file, a single signal generator connection is valid. For more information refer to the Test Case Manager Software and Supported Instruments topics.

3. Using the PXB online documentation, connect the needed number of signal generators to the PXB, but do not use the PXB GUI to configure or recognize the connected signal generators.

   The software's PXB settings configure the signal generators connected to the PXB.

4. In the tree window, click the PXB (Connected) node to display the PXB Setting window.

5. Within the PXB Setting window, configure the required number of signal generator connections.

   The PXB uses this information to identify and control the signal generators.

   1. Enter the SGn VISA Address where n is the SG number (SG1...n).

      When entering the address, ensure that all colons (used in both TCPIP and GPIB connections) are present in the completed VISA Address.

      

      The software does not test these connections. But the signal generator connections can be tested by using the signal generator selection under the Hardware Connections and Settings Node. If they are tested under this node, it does not affect the test if they remain connected as identified by the node (Signal Generator (0...n:Connected)).

   2. Using the SGn Port Name field, select the PXB port that will be assigned to the signal generator.

   3. Using the SGn Port Type field, select the port type:

      • Digital uses the PXB's digital I/O bus to connect to the external instrument.

      • Analog uses SMB(f)-to-BNC(m) cables to connect the PXB's analog I/Q connectors to an RF signal generator capable of receiving analog I/Q inputs

6. Configure the Properties for the PXB.

   1. Set each of the trigger fields.

   2. Determine whether the Baseband Offset State should be enabled.

      When enabled, the offset frequency shown in the Baseband Offset Frequency cell is applied to the signal generator upon downloading the waveform. The baseband offset helps mitigate the effects of LO feedthrough. This is especially useful when using a single instrument that combines a high power interferer with a low power wanted signal. In this instance, the baseband offset shifts the wanted signal from the center frequency by the amount entered, thereby helping to avoid the effect of a large DC feedthrough.

   3. Set the reference for the PXB.

      The PXB external reference, may be another instrument or another device, such as a time-standard used in your facility. This external reference signal provides the synchronization and timing for all of the PXB circuits. The signal is connected from its source to the SMB connector labeled EXT REF IN on the PXB rear panel.

      A valid reference signal for the external reference:

      • Must be in a range from 1 MHz to 100 MHz in the reference frequency setting

      • Have an input power range of –5 to 10 dBm

      When the PXB detects a valid reference signal at the EXT REF IN connector, it automatically displays an indicator on the status bar, showing the presence of an external reference frequency at the rear panel. If the signal at the EXT REF IN connector is out of range or not detected, the PXB displays an error message its status bar.

7. Set the Closed Loop Feedback Configuration properties.

   For more information on the properties, use the hints, and review the Closed Loop Feedback Configuration topic.

8. With some test case exceptions, if the Signal Studio software is not licensed for waveform files, but is licensed for real-time signals (Wxx license), check the Apply Wxx RT License for waveform file.

   

   For more information on this feature and the exceptions, see the Test Settings topic.

   To determine whether the instrument is licensed for Signal Studio waveform files, see the license listing in the Signal Studio Licenses property. The software displays the license listing after connecting to the instrument.

9. If needed, enable Delta Update State by clicking the checkbox so that a check-mark shows.

   When enabled, this setting upon clicking Execute reduces the time it takes to configure the PXB. This is done by the PXB only implementing those changes that are different on a subsequent download