■O
o
O
O
a>
a
o
101
n
b
3
102
Z
10 3
104
10s
106
107
10®
1 o 9
- - h - M
L — j- - h -4
L . .
-------------
10ms
-----0.1s
-------------
1s
-------------10s
- ) — |
----------------------------
L.4 4 - 4
L 4 - h -
L
- + ■ 4 - 4
L - h - 4 -
l - 4 ™
•
--------
(Hz)
0.1
1
10 100 1K 10K 10OK 1M 10M 10OM
Frequency
Fig. 5-3 N u m b e r o f p erio d s w ith tim e & fre q u e n c y
-------
T h e n u m b er o f d isp lay d ig its is five fo r 10 m s, six fo r 0.1 s, seven fo r 1 s,
an d e ig h t fo r 10 s.
5-3-3 . P e rio d M e as ure m e n t (P E R IO D B)
T his is b asically th e sam e as th e fre q u e n c y m e as u re m en t (F R E Q . B). (See
5-3-2 .)
5-3 -4. T im e In te rv a l M ea su re m e n t (T .l. A -*■ B)
T his is basically th e sa m e as th e fre q u e n c y m e as u re m e n t (F R E Q . B) a nd
p erio d m e asu re m e n t (P E R IO D B). T h e m ea su re m e n t tim e is d e p e n d e n t
on th e signal to be m e asu re d a n d n o ise rid in g alo n g w ith it causes trigg er
e rro r, w hic h is c alc u la te d by e q u a tio n ( l) in 5-3-2. E q u a tio n (T) app lie s to
a sine w av e; fo r a p u lse, h o w e v er, th e trig g er e rro r e xp re ssed w ith th e slew
ra te (S R ) w o uld a ffo rd a b e tte r u n d e rs ta n d in g :
1.4 x \/( c o u n te r in te rn a l n o ise )2 + (N oise o n in p u t)2
T rigg er e rro r =
----------------------------- ^
---------------------------------
(S rm s)
5-9
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