Viewing and Configuring Computer VGA Measurement Results

Viewing and Configuring Computer VGA Measurement Results

The screenshots in this topic show how to view computer VGA signals and measurements in NI VMS. Refer to Analog Hardware for devices needed to acquire computer VGA signals. No synchronization is present in the signal itself, see Figure 1. The synchronization is handled by a separate horizontal sync, H-Sync, and vertical sync , V-sync, signals.

Figure 1: The Computer VGA signals, also referred to as RGBHV, have no sync in the signals themselves.

Figure 2: A Computer VGA test matrix example

Color Bars

Figure 3: Color Bar signals in a Computer VGA signal.

Figure 4: Measurements of the Computer VGA test signal from Figure 4.

Multiburst

An example of an acquired Multiburst signal for Computer VGA signal is shown in Figure 1. The measurement results are shown in Figure 5.

Figure 5: Measurement of Multiburst frequency response for a UUT, a portable computer.

One challenge is that the resolution of the test pattern used is governed by the pixel resolution of the UUT under test. So in the case of 1024x768 the frequencies that are tested do not follow the traditional burst of 5 MHz, 10 MHz, 15 MHz, 20 MHz, 25 MHz and 30 MHz.

Noise Spectrum

The approach for Noise Spectrum for Computer VGA is basically identical to that of the previous examples for CAV RGB testing and for S-Video as well as CVBS. As with the other CAV synchronization test cases, the user can select the bandwidth. Default is 30 MHz. Note: CVBS and S-video has a fixed bandwidth, e.g. 6 MHz for PAL.

Figure 6: The noise spectrum for the UUT is flat and offers good frequency performance.

Figure 7: The measurements of the noise spectrum performance of the portable PC.