EXT SYNC
WHY EXT SYNC
(EXTERNAL SYNCHRONIZATION)?
When the Motion Analyzer is operating in ROC mode the Imager
is driven at the record rate and exposure selected with the
Keypad. The recording does not start until the Imager begins the
next frame. Some applications may require that each frame start
at a precise point in the motion being analyzed, consequently a
delay until the start of the next frame is unacceptable.
Suppose we need to check the amount of flex in a turbine blade
as it rotates past the 90 degree mark. The turbine is rotating at
something close to 10,000 rpm which means the blade will pass
the study point every 6 milliseconds. No combination of record
rate and exposure available on the Keypad will capture the blade
one picture per revolution.
To take a picture of the blade at the same spot every time, we
need the blade itself to control when the Processor takes a
picture. A sensor that produces a pulse each time our blade goes
by is needed. Once the sensor is in place and operating, its
output is connected to the EXT SYNC input on the back of the
Processor. An EXT SYNC mode recording is made and we have
our blade captured once every revolution.
FRAME -84
ET
-
000001.6800
PLAY 30
TRIG
ROC
SYNC
ID
02
REC
50
EXP
250
IMG
B/1
X
40
Y
30
D
050.0
PIX
256
TIME 12:19:06 DATE 05/21/91
SYNC
Indicator
6.15
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