Real Time

Configuring the Signal Generator

Use this procedure when the signal generators are not controlled by the PXB. but rather the signals are directly downloaded to the signal generators by the software.

When multiple signal generators are used for tests, each signal generator has to be configured separately.

Select the Signal Generator node located under the Hardware Connections and Settings node.
After either leaving or entering a new Signal Generator name, enter the VISA Address:
1. Click the VISA Address cell to display the hint that provides the description and examples of the address entry.
2. Enter the VISA Address
  
  When entering the address, ensure that all colons (used in both TCPIP and GPIB connections) are present in the completed VISA address
Use the Test Connection button to connect to the instrument identified in the VISA Address setting.

If the connection is successful, the connection status of the instrument changes to Connected.

After making the connection, the software lists all of the Signal Studio licenses from the instrument. To view the list, see the Misc section at the bottom of this settings window.
If there is a need to create a waveform file without having to download it to an instrument, enable the Offline Mode.

With Offline Mode enabled, select the signal generator Model Type. This ensures that the SCPI commands shown in the SCPI Log Viewer are the correct commands for the selected model type.
If performing a test that requires closed loop feedback testing, click the HARQ/TA Test Support checkbox to where it shows as being checked.

This enables the settings shown in the Closed Loop Feedback Configurationsection.
Configure the Properties for the signal generator:
1. Click Path Loss and enter the value in dB.
  
  The path loss value enables the signal generator to compensate for loss due to cables, connectors, combiners, etc.from the RF Output of the signal generator to the input of eNB/BTS.
2. Click Trigger Polarity, and select either positive or negative.
3. Click Trigger Delay, enter the delay value that compensates for the trigger latency of the instruments and enables the instrument's RF Output to align with the eNB/BTS 10 ms frame trigger signal. To compensate for the instrument trigger latency, use the following formula:
  
  Trigger Delay = 10 ms - trigger latency
  
  To find the trigger latency for each instrument, refer to that instrument's Data Sheet. For LTE tests using the N5172B EXG and N5182B MXG, the trigger latency varies depending on the channel bandwidth.
  
  The trigger delay is applicable only when the Trigger Type is set to either Pattern Trigger 1 (Trigger & Run) or Pattern Trigger 2 (Trigger & Run).
4. Click Trigger Type and select the desired triggering method.
  
  The default selection of Pattern Trigger 1 (Trigger & Run) holds the playback of the waveform until the signal generator receives a trigger.
  
  For the PXB, EXG, and MXG instruments, after downloading the signals and if the instruments are waiting for a trigger, the software displays the annunciator TRIG ARMED in the right corner of the message bar.
  
  For the Clause 7 tests, the instrument setup diagrams already account for the trigger using the 10 ms frame pulse from eNB/BTS.
  
  To use the test signal without synchronizing with eNB/BTS, select Free Run from the drop-down menu.
5. 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.
If enabled, set the Closed Loop Feedback Configuration properties.

For more information on the properties, use the hints, and review the Closed Loop Feedback Configuration topic.
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.
If needed, use the buttons at the top of the setting window to add instruments for use with multiple signals such as an interferer, or to delete an instrument. In some instances, the software also allows the use of a single instrument for a multiple carrier test signal. For more information refer to the Test Case Manager Software topic.

if instruments are added, each instrument needs to be configured.