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802BT/802R Video Test Generator User Guide 45
Restoring factory settings
This section describes how to set and restore the generator system parameters.
System Parameters
The following system parameters are stored in the 802’s non-volatile system memory:
• The reference rate calibration factor. The 802 uses a crystal controlled oscillator as the
reference for all timing signals. The crystal frequency has a maximum error of ±50 ppm.
The 802 hardware and firmware is capable of compensating for this small amount of
error by applying a user set calibration factor. The factory default setting is 1.000 for the
calibration factor. Use the
RATC
command to set the pixel calibration factors.
• The maximum pixel clock rate used for error checking formats. All 802 generators will
operate, to some extent, at pixel rates beyond their spec sheet limits. The maximum
rate can be set to a higher limit if it is known that a particular unit will work reliably at
the higher limit. Use the
JRAT
command to set the maximum pixel rate used for error
checking of analog formats.
• The gamma correction flag. This flag determines whether individual formats can control
the application of gamma correction or if gamma correction is disabled regardless of a
format’s setting. The factory default setting is to allow gamma correction to be
controlled by individual formats. Use the
GAMC
command to enable or disable the
gamma correction flag.
Setting and restoring system parameters
There are two ways of changing the settings of these parameters:
• They can be restored to their default factory settings as part of a user initiated system
reset. This will also restore the entire format storage memory to its factory default
contents.
• A suitably equipped computer or terminal connected to one of the communications
ports can be used to set the parameters to user defined settings.
When the generator is reinitialized, each format in the standard library is tested
(one-at-a-time), to determine if the format parameters are fully supported by the generator.
This algorithm is necessary because the standard format library is used across all
generators. If there are some limitation the generator applies a format justification
algorithm. In these cases the generator stores a modified version of the format under a
similar name. If the format is beyond what can be corrected the format is left out of the
generator’s list of formats.
WARNING: The initializing the generator permanently and irreversibly removes all
user-created formats, custom images, test sequences and directories from memory.