Kenwood FC-757, Инструкция по эксплуатации, Страница: 36 / 40

6 - 4 Relationship between period measurement mode
and t i m e interval mode
It is s t r o n g l y recommended t h a t the period meas-
urement mode be used instead of the t i m e in-
t e r v a l measurement mode to measure the t i m e
i n t e r v a l between t w o s i m i l a r edges of the same
signal ( f o r example, the t i m e i n t e r v a l between
one positive-going edge and the next positive-going
edge of the same signal is measured.).
The reasons are as f o l l o w s :
- If fine resolution is selected, the period measure-
ment mode outputs higher precision measurement
d a t a than the time interval measurement mode
does. In the time interval measurement mode,
as the number of time i n t e r v a l s ( 1 , 10, 100, and
1000) increases, the error rate w i l l be bigger
and bigger accordingly. A s a result, j i t t e r - a f f e c t -
ed output values may be displayed more often
because the better resolution requires more dis-
play digits f o r more accurate measurement is
not assured.
The period measurement mode produces the same
measurement error, irrespective of resolution
settings.
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6 - 5 Use of T R I G L E V E L control
T R I G L E V E L control ® is provided to adjust
the trigger levels of the input s i g n a l s to
C H A N N E L A . If the adjust is pressed (set to
the P R E S E T p o s i t i o n ) , a l m o s t the average level
of the input s i g n a l s is selected as the trigger
level. A l m o s t the a l l the operations can be
performed based on t h a t trigger level. However,
t h i s level should be changed if the signal
w a v e f o r m s shown in figure 6 are processed.
The trigger level to be selected by setting the
controller to the P R E S E T position is indicated
by the broken line a t the bottom in the F i g u r e .
T h i s trigger level is an average of the pulse
s t r i n g . However, t h i s level nears the noise found
in the signal w a v e f o r m . A s a result, it m a y
cause a pseudo trigger error.
T o change the triggering position to prevent the
trigger error, use the T R I G L E V E L c o n t r o l .
If the controller is pulled and rotated in either
direction (clockwise or counterclockwise), the
current level position moves to either a desired
earlier position or later position.