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802BT/802R Video Test Generator User Guide 63
Creating custom formats
You can create new signal formats for the generator and add them to non-volatile memory.
You can create formats through VGM or by using a command line interface (either the
RS-232 port or the IEEE-488 port). The recommended procedure for creating new formats
is to use VGM. VGM contains the algorithms for ensuring compatibility between format
parameters where there are dependencies in their respective values. Please refer to the
VGM online help for information about creating formats using VGM.
Determining the signal specifications of the display
Your custom format will be based on the specifications of the display under test. Typically,
you can find the information required for the format in the detailed specification sheet for
the display. At a basic level, you must determine if you are working with an analog or a
digital display. An analog display can show an endless range of colors or shades of gray.
Analog displays normally accept video signal levels in the 1 Vp-p range. Digital displays
are more limited and can display only a few gray levels or a limited number of pre-defined
colors. These displays normally accept TTL video signals in the 4 Vp-p range.
Creating custom formats using the command line interface
There are two methods for creating formats through the command line interface. The first
method is to use the FMTN command to set all format parameters in the format buffer to
their default values, and then modify each value. The second method is to select an
existing format to use as a template for the new format, and then modify only the values
needed to create the new format. When using this method, you can save the new format
under a new name or the existing name.
Independent of the method you choose, you can enter each command interactively or,
using your computer, create a text file containing all the commands you want to issue, and
then download the text file to the generator. For instructions on creating and downloading
text files, see “ Sending commands from text files ” on page 16.
Creating a new format
The FMTN command is used in creating a new format. This command sets all of the
format parameters to known, default values. For a list of the parameters and their default
values, see “ FMTN ” on page 331. Use the following procedure to create a new format
using interactive commands.