1-Channel Fade (ext in) Configuration

 

 

1. Basic Introduction and Turn-On

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When the PXB is powered on, it displays the "1 Channel Generate" configuration, the most basic configuration in the Configuration Browser as the default. The PXB will only display configurations that the PXB’s baseband and I/O card option structure will support.

    1. To turn on the PXB, press the front panel power hardkey.

    2. Allow the PXB to boot and display the firmware.

    3. Select the "Fade (ext in) 1 Channel" configuration from the Configuration Browser.

    4. The block diagram for this selected configuration is displayed on the Block Diagram tab.

 

2. Register External Instruments

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The PXB is designed to use a variety of external instruments to provide external inputs or received the output of the PXB. These external instruments can be controlled by the PXB firmware; however, the external instruments must be registered within the firmware prior to being available for use.

This example setup procedure uses the N5182A MXG signal generator and the N9020A MXA signal analyzer as external instruments. 

The registration process only needs to be performed once per instrument. If all of the instruments that you plan to use are already registered (see step 1), you may skip to the next section, "3. Assign External Instruments."

For this example, an Agilent N5182A MXG signal generator is being registered.

    1. Click the External Instrument Table tab to display the External Instrument Table. Closed
      Illustration…

      This illustration shows the External Instrument Table with that has been populated with several external instruments used with the PXB.

The External Instrument Table displays the external instruments that are currently registered with the PXB firmware. External instruments that can be registered are:

The table displays the name, instrument type, address, and I/O Port (this is discussed more in the next step) of each registered external instrument. If no instruments are displayed in the table, then no instruments are currently registered.

    1. Select the Add button to start the registration process. This displays the Register External Instrument dialog box. Closed
      Illustration…

    1. In the Name text box, enter "MXG1" or another name to describe your signal generator. For the remainder of this example, the signal generator is referred to "MXG1".

    2. In the Family drop down list, select instrument family that describes the instrument's family. In this case, select MXG.

    3. In the Visa Interface drop down list, select the interface that the PXB will use to communicate with the instrument (TCPIP0 = LAN or GPIB0 = GPIB).  

    4. In the Address text box, enter the address specific to the instrument that you are registering.

As you proceed through this step, use the actual addresses for your instruments.

 

    1. Click the OK button to complete the registration. The External Instrument Table should now show the instrument that you just registered (an MXG, in this case).

    2. Repeat steps 2 through 7 for the MXA signal analyzer required for this example configuration.

    3. Click the Block Diagram tab to return to the configuration block diagram that was originally displayed.

 

3. Assign External Instruments and Load Configuration

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External instruments must be selected and set up for the PXB.

You will see an I/O1 Port A1 block (this block is an input which connects to a signal analyzer), a Fader 1 block, and an I/O2 Port A2 block (this block is an output which connects to a signal generator). You will also see two (Unassigned) blocks which represent two unassigned blocks for two external instruments (the signal analyzer and the signal generator).

 

4. Set Up Signal Analyzer

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When the configuration is loaded, the Settings Browser replaces the Configuration Browser in the left panel of the user interface. Each block from the block diagram is also listed in the Settings Browser. You are now able to view and edit the settings for each block. Now we will set up the signal analyzer.

The PXB user interface provides basic control of the signal analyzer via the LAN/GPIB interface. The PXB and signal analyzer are also connected via the digital bus for waveform data transfer. 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.

    1. Review the General Settings tab.

      It provides some basic settings which allow control of the signal analyzer from the PXB. For additional information about each setting, refer to General Settings.

    1. Use the Test Connection button above the tab to verify that PXB and the MXA are communicating with each other.

Note that there are also buttons that will preset the signal analyzer, update the PXB with the signal analyzer settings, and level the signal analyzer's input.

    1. Return to the block diagram using the Block Diagram button.

 

5. Set Up Input I/O Port

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Now we will set up the input I/O block. This block is the interface from the signal analyzer as it connects with the PXB.

 

6. Set Up Fader Block

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Navigating the Fader block is slightly different and a little more complex than other configuration blocks. You will see that fading has two areas for setup: Master Setup and Fader Paths. For this reason, the fading procedure is organized in three parts:

Fader Block Introduction

The Fader block has two areas, Master Setup and Fader Paths. The Master Setup interface is similar to the other block interfaces that we have explored. The Fader Paths interface is a table that defines each of the fading paths.

    1. Open the Master Setup settings for Fader1 by selecting Master Setup 1 from the Settings Browser. If necessary, expand the settings beneath the Fading label by selecting the icon. Note that the Fader Paths label is beneath the Master Setup label as shown. Closed
      Illustration…       

    2. Notice that Master Setup has a Fader Setup tab. If you are using a configuration that has a Master Setup with more than one Fader block, such as 2 Channel Fade (ext in), there is also a Correlation tab (highlighted in the illustration). Closed
      Illustration…        

      Note that when a configuration's Master Setup has more than one Fader block, multiple Fader settings are displayed on the Fader Setup tab as well. This area is also highlighted in the illustration.

    1. With the Fader Setup tab selected, review this tab's settings.

    2. When you use a configuration that has a Master Setup with more than one Fader block, you can access the Correlation tab to edit the correlation table defining the degree of correlation for the paths between the Fader blocks.

    3. After reviewing the Master Setup, open the Fader1 Paths table by selecting the Fader1 Paths label in the Settings Browser.

    4. Review the Fader1 Paths table. Closed
      Illustration…

By scrolling down, you will notice that there are 24 rows representing each of the PXB's maximum of 24 paths. By scrolling across the table from left to right, you can see there are a variety of settings used to define each path.

Basic Fading Setup

Setting up the Fader block can be as easy as selecting the appropriate fading model that you are using from a list of standard technologies.

    1. With Fading expanded in the Settings Browser, select Master Setup 1 to view the Master Setup settings.

    2. Select Fader 1 Channel Model to display the drop-down button at the right edge of its settings cell. Then select the drop-down button to display a list of the available fading channel models.

    3. For this example of the Fader 1 Channel Model setting, select W-CDMA, then select Base Station, and then select Moving Propagation. Closed
      Illustration…

As you can see, there are many channel models included in the PXB to choose from.

    1. Once you have selected Moving Propagation, ensure that Fader1 Paths is displayed below Master Setup 1 in the Settings Browser. If not, expand the Master Setup 1 using the icon to display it. 

    2. Select Fader 1 Paths to display the number of paths, the fading type, the spectral shape, the delay values, and a variety of other variables – which are all based on the standard for the selected channel model.Closed
      Illustration…

    3. These channel model variables are displayed in tabular format This table is complex and can list approximately 20 variables across the ”r;X-axis”, although just a few can be seen without scrolling. All of the available paths are listed along the ”r;Y-axis”.

    4. Select the Master Setup 1 from the Settings Browser to return to the Fader Setup settings.

 

Fader Paths Customization

Having just set up the Fader block by selecting a channel model from a list of standard technologies, we will look at using one of these standards and customizing it to fit any specific fading needs you may have.

  1. Change the Fader 1 Channel Model setting from the previous selected W-CDMA, Base Station, Moving Propagation standard by selecting Mobile WiMAX, then Vehicular A(60 kph) in the drop-down list, as in step 3 of the Basic Fading Setup procedure above.

  2. Select Fader 1 Paths to display the number of paths and all of the other variables for the selected channel model.

It’s easy to see that this new standard has different properties than the one we looked at previously.

  1. Select the Enabled check boxes for paths 7 and 8 so they are both checked. You have just added two paths to the channel model.

  2. For paths 7 and 8, click the Fading Type drop-down button and select Suzuki for each path.

  3. Enter "17.50 dB" in the Loss column for path 7 and enter "22 dB" in the Loss column for path 8. These are both arbitrary values. You could enter a meaningful value for your test requirements.Closed
    Illustration…

We have just added channels and changed settings to show that you can customize your Fader setup by manually adjusting the channel properties to meet your specific needs. These types of changes may be made to any of the attributes of the standard settings definitions. You have two different ways to set up fading: From Standard and Custom.

  1. Return to the block diagram.

 

7. Set Up Output I/O Port

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The output I/O port is used as the output interface to an external instrument (either a signal generator or an N5102A Digital Signal Interface Module) at the output of the PXB. The output I/O Block has its own settings that are customized for the output. For additional information, refer to the I/O Port Setup tutorial.

The following is a quick review of how each of the tabs can influence the output of the PXB.

    1. Review the General Settings tab.

The General Settings tab provides information about the I/O port and can be used to make changes to the I/O port. You will notice that the Mode setting is a read-only entry that displays Output indicating that this I/O port is being used as an output I/O.

    1. Select the AWGN Settings tab to review this tab's settings. This tab is used to add and control Additive White Gaussian Noise (AWGN) to the output signal at the I/O port. The AWGN Graphics tab provides a graphical description of some of the AWGN settings.

    1. Select the Marker Settings tab to review this tab's settings. For additional information, you may also refer to the Marker Basics tutorial.

The I/O output block can pass the existing markers from the input source (the baseband generator or I/O input block) or can dynamically generate new markers based on the waveform present at the I/O output block. Markers that are generated from an output I/O block that is receiving a single-input waveform are merged with the waveform as it was received. Therefore, if the original waveform has had fading or interference added, the degraded waveform is used to generate these markers. This is important to note because dynamic markers use the values of the waveform samples to determine when markers are generated.

Any output I/O markers will override markers previously embedded in the original waveform file or generated by a user-created marker file or input I/O block.

    1. Return to the block diagram.

 

8. Set Up Signal Generator

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The PXB provides direct control of several of the signal generator settings. These settings include the output frequency, the output amplitude, and the internal marker routing and more. It does not provide control of all the signal generator settings.

The following is a quick review of how each of the tabs can be used to control the signal generator from the PXB.

The values shown in the display not reflect the actual signal generator state unless an update to instrument (Update To Inst) or an update from instrument (Update From Inst) is performed. The PXB uses the actual values from the signal generator when necessary.  

 

9. Play Waveform

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Once the PXB configuration is set to meet your test needs, you can simply calibrate the system power and play the signal from the connected signal analyzer via its digital bus through the input I/O block, the Fader block, and the output I/O block to the connected signal generator via its digital bus.