Tektronix 1503C, Руководство пользователя, Страница: 112 / 128

Operator Troubleshooting
D–4
1503C MTDR User Manual
Size of Reflection % / division
r
/ division
100% to 80% (1
r to 0.8 r
) 20 .20
80% to 40% (0.8
r
to 0.4
r
) 10 .10
40% to 16% (0.4
r to 0.16 r
) 5 .05
16% to 8% (0.16
r
to 0.08
r
) 2 .02
8% to 4% (0.08 r
to 0.04
r ) 1 .01
4% or less (< 0.04
r
) 0.5 .005
+1
r
=
∞
W
+.03
r
= 53.1
W
SOURCE
STEP
GENERATOR
INCIDENT
VOLTAGE
REFLECTED
VOLTAGE
D
2E
R
S
50
W
Z
O
50
W
LINE
D
E
+1r =
+
0.5
r=
0
r =
-
0.5
r=
-1r =
+100%
+50%
0%
-50%
-100%
1 W
150
W
50W
16.7
W
0
W
LOAD
R
L
r
= REFLECTION COEFFICIENT
r
/ DIV
r
/ DIV
r
/ DIV
r
/ DIV OHMS OHMS OHMS
.20 .10 .05 .02 .01 .005
50W
SOURCE
50W
SOURCE
50W
SOURCE
The risetime or amplitude of received reflections may be signi-
ficantly degraded or attenuated by two-way losses of the line .
1
r
= 100%
1
150
50W 50W 50W
1000
500
300
200
100
70
40
1000
600
400
300
200
100
90
80
70
60
45
40
120
100
90
80
70
60
70
68
66
64
62
60
58
56
54
52
49
48
59
58
57
56
55
54
53
52
51
51
52
53
54
Figure D–3: Slide Rule 50
W
Source
If the reflection is downward from the 50
W
or 75
W
reference level, set the reference
level to the top of the chosen scale. If the reflection is toward a higher impedance
than the reference level, set the reference level to the bottom of the chosen scale.
Then count off the right number of divisions and subdivisions to locate the level
corresponding to the peak of the reflection and read the corresponding impedance
levels (Ohms) on the adjacent sliding scale.