Automatic test instrument for multi-format video generation and capture

Abstract

A method for producing a static composite video signal, e.g., for delivery to a unit under test (UUT), in which a prime image memory (PIM ) holding a main bit mapped image is provided, sync and blanking patterns for lines of the video signal being generated are held in a composite sync memory (C-Sync ), and a series of arbitrary bit line patterns defined in a test program are held in two user specified pulse memories (USPs ). Data blocks are arranged in a circular queue in a line parameter memory (LPM ), each data block corresponding to a complete video line and containing pointers to specific entries in the PIM ( ), the C-Sync ( ) and the USPs ( ) and a flag indicative of scan direction. Production of the video signal is initiated by reading the LPM ( )and extracting the pointers from the data blocks for a first line of the video signal being produced. Bits from the PIM ( ), C-Sync ( ) and USPs ( ) are obtained based on the extracted pointers and combined to thereby form the video signal. The length of the first line of video signal being produced is monitored to determine when the first line of video is complete, and then production of the video signal is continued line by line in the same manner. Modulated and non-modulated raster video signals can be produced by imposing a deflection waveform on the image. Also disclosed is a method for drawing an image on a screen, three streams of data are created by directing a preload value to a counter ( ) having memory addresses and using the memory addresses to obtained data from the memory ( ), each stream of data is converted to an analog signal by means of a respective digital to analog converter ( ), and the analog signals are directed to output channels ( ). The three streams of data preferably represent X-deflection data, Y-deflection data and Z-intensity data.