Figure 3-25.—Test message generator.
Test Pattern Mode
The test pattern mode of operation, used only
when the TMG is installed in the PA cabinet, displays
two symbols repeated every 90 degrees for a total of
eight symbols. All the word designator bits and the
TEST PATTERN switch must beset too btain this
display. The test pattern is normally output to one
group of consoles at a time.
Output Data Request (ODR) Mode
The output data request (ODR) mode of operation
generates one data word in response to each ODR
received from the equipment undervest. ODR mode
is used when testing the PA, VSS, or consoles with
DCI.
The 2/20 Cycles-Per-Second (CPS) Modes
The 2/20 cycles-per-second modes are a variation
of the free run mode. The two-cycle mode repeats up
to a four-word message twice a second (every 500
milliseconds).
The 20-cycle mode repeats the
message 20 times a second (every 50 milliseconds).
DISPLAY POFA/PEFT
A tactical display system is a somewhat
complicated combination of equipments. The sheer
number of consoles (PPIs), radar distribution switch-
boards, radar azimuth converters, pulse amplifier/
symbol generators or PA/CIGARS or DCI/CIGARS
tends to present a formidable maintenance task.
One of the primary tools available to the
maintenance technician is the display programmed
operational functional appraisal (POFA) and on some
classes of ships, the display peripheral equipment
functional test (PEFT).
Display POFA
The display POFA grouping of tests is designed to
be loaded and run in the computer in lieu of the
operational program.
Display POFA subtests are
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