Tektronix 434, Инструкция по эксплуатации

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Operating Instructions—434
F ig . 2 -1 2 . M e a s u rin g phase d iffe re n c e .
F ig . 2 -1 3 . H ig h re s o lu tio n p h a s e -d iffe re n c e m e a s u re m e n t w ith in ­
creased sw eep ra te .
12. M u ltip ly th e measured distance (in divisio n s) by
4 5 ° /d iv is io n (sweep rate) to o b ta in th e e xa ct a m o u n t o f
phase d iffe re n c e .
4 5 ° /d iv is io n -5- 10 = 4 .5 ° /d iv is io n . Fig. 2-13 shows th e same
signals as used in Fig. 2-12 b u t w ith th e M A G s w itch set fo r
10X m a g n ific a tio n . W ith a h o riz o n ta l d iffe re n c e o f six d iv i­
sions, th e phase d iffe re n c e is:
E X A M P L E . Assume a h o riz o n ta l d iffe re n c e o f 0.6 d iv i­
sion w ith a sweep rate o f 4 5 ° /d iv is io n as show n in Fig.
2
-
12
.
Phase
D iffe re n c e
H o riz o n ta l
d iffe re n c e
(divisions)
m ag n ifie d
X sweep rate
(degrees/div)
Using the fo rm u la :
Phase D iffe re n c e =
h o riz o n ta l
d iffe re n c e
(divisions)
sweep rate
(degrees/div)
S u b s titu tin g th e given values:
Phase D iffe re n c e = 6 X 4 .5 °.
S u b s titu tin g th e given values:
The phase d iffe re n c e is 2 7 °.
Phase D iffe re n c e = 0.6 X 45°
C om m on-M ode R ejection
T he phase d iffe re n c e is 2 7 °.
High R esolution Phase Measurements
M ore accurate dual-trace phase measurements can be
made b y increasing th e sweep rate ( w ith o u t changing the
V a ria b le T IM E /D IV c o n tro l s e ttin g ). One o f th e easiest
ways to increase the sweep rate is w ith th e M A G s w itc h .
T h e m ag n ifie d sweep rate (in term s o f degrees/division) is
d e te rm in e d b y d iv id in g th e sweep rate ob ta in e d p re vio u sly
b y the a m o u n t o f sweep m a g n ific a tio n .
E X A M P L E . I f the sweep rate were increased 10 tim es
w ith th e m a g n ifie r, the m a g n ifie d sweep rate w o u ld be
The A D D fe a tu re o f the 43 4 can be used to d isp la y
signals w h ic h c o n ta in undesirable co m ponents. These
u n d e s ir a b le
c o m p o n e n ts can be e lim in a te d th ro u g h
co m m o n -m o d e re je c tio n . T he p re ca u tio n s given under
A lg e b ra ic A d d itio n should be observed.
1. C o n n ect the signal c o n ta in in g b o th th e desired and
undesired in fo rm a tio n to th e CH 1 c o n n e c to r.
2. C o n n ect a signal s im ila r to th e u n w a nte d p o rtio n o f
th e Channel 1 signal to th e CH 2 co n n e c to r. F or exam ple,
in Fig. 2 -1 4 , a lin e -fre q u e n c y signal is connected to Channel
2 to cancel o u t the lin e -fre q u e n c y c o m p o n e n t o f the
Channel 1 signal.
2 -2 2