Locating CVBS Test Signals for Measurement Tutorial

Locating CVBS Test Signals for Measurement Tutorial

This tutorial adds more detail to the directions in Locating Test Signals for Measurement. In this tutorial we specify timing locations for a multiburst test pattern, a modulated staircase pattern, and a 2T pulse pattern that are contained in a PAL CVBS test matrix. For the purposes of the tutorial, we use the example PAL TPG.vbf and PAL TPG.loc files that install with NI VMS.

Choosing a template for defining locations

1. Verify that you have either acquired the video signal or opened the .vbf file containing the test patterns whose locations you want to specify. In this tutorial, we choose PAL TPG.vbf, which consists of a PAL test matrix that contains a multiburst pattern, a modulated staircase, a 2T pulse, and other patterns.
2. On the Analysis tab, click Select Locations. Clicking Select Locations browses by default to several standard .loc files installed with NI VMS.

   

3. Select PAL TPG.loc. Normally you could use this as a template for your custom .loc file, but in this tutorial our sample .loc file is already edited to match locations in our sample .vbf file, so we duplicate what's already set up.
4. (Optional) Enter a brief description of the .loc file in the Description control, such as PAL Matrix from TPG20.
5. Click Save As and rename the .loc file to PAL TPG tutorial.loc before you begin editing to avoid altering the template file.
6. Close the Measurement Locations Editor.

Displaying a multiburst pattern in the Measurement Locations Editor

To display the video line that contains the test pattern whose location you want to specify in the Measurement Locations Editor, complete the following steps:

1. On the display on the Picture tab, drag the horizontal cursor (the horizontal dotted yellow line) to a line that is within the multiburst pattern. We can see that a multiburst pattern is present in lines 60 to 95 in frame 1. Because every video line in a test pattern is identical, you can choose any line in the multiburst pattern. Dragging the cursor updates the Cursor Line indicator. Make note of the Cursor Line value.
2. Click Edit Locations to open the most recently saved .loc file in the Measurement Locations Editor, in this case PAL TPG tutorial.loc.
3. Enter the value you made note of in the Cursor Line indicator in the Line control directly below the display on the Measurement Locations Editor. In this tutorial we enter 68, and the waveform of the multiburst pattern is displayed.

Specifying locations of a multiburst pattern

To specify the locations of a multiburst pattern, complete the following steps:

1. Below the display on the Measurement Locations Editor, click the Multiburst tab.
2. On the Multiburst tab, verify Enable is checked.
3. (Optional)Enter a brief description of the test pattern in the Comment control, including the start and end lines of the test pattern. Enter F1 lines 60-95, F2 lines 372-407, as a reminder of the blocks of lines containing the multiburst pattern in frame 1 and in frame 2.
4. From the Update from Cursor list, select the first timing parameter in the list, Flag 1 Level High.
5. Drag the cursor along the display on the Measurement Locations Editor to the center of the first flag's highest level, at about 14 us. The value in the Flag 1 High control updates to the cursor position.
6. Continue selecting timing parameters in the Update from Cursor list and dragging the cursor to the parameter's location to update the control for each parameter.

   

   Figure 2: Specifying the location of the final timing parameter for the multiburst signal, Burst 6 End, at about 59.86 us.

7. Click Save.

Displaying a modulated staircase pattern in the Measurement Locations Editor

We move on to the next test pattern in the PAL TPG.vbf test matrix, a modulated staircase. To display this pattern in the modulated staircase, complete the steps in Displaying a multiburst pattern in the Measurement Locations Editor, except choose a line in the modulated staircase, which is between lines 96 and 131 in frame 1.

Specifying locations of a modulated staircase pattern

To specify locations of a modulated staircase pattern in PAL TPG.vbf test matrix, follow the instructions in Specifying locations of a multiburst pattern, except choose the Multiburst tab and specify its locations in the Update Cursor list. See Figure 3.

Figure 3: Specifying the location of the first timing parameter, the start of the second packet, at about 39.96 us.

Displaying a 2T pulse pattern in the Measurement Locations Editor

The 2T pulse signal does not take up a full video line, unlike the color bar and multiburst signals. In the test matrix PAL TPG.vbf, there happens to be a 2T pulse signal in the same block of video lines that contain the modulated staircase. Therefore, we don't need to change the Measurement Locations Editor display for this test signal.

Specifying locations of a 2T pulse pattern

To specify locations of a 2T pulse signal in PAL TPG.vbf test matrix, follow the instructions in Specifying locations of a multiburst pattern, except choose the 2T Pulse tab and specify its locations in the Update Cursor list. This test element has only 1 timing parameter. See Figure 4.

Figure 4: Selection of locations data for a 2T pulse. Only one parameter needs to be set.

For further examples of specifying test signals and elements for a PAL CVBS signal, refer to Locating CVBS Test Signals for Measurement Tutorial.