Chapter 6 - Testing ControlNet Trunk Cables
6.3
Testing using a Time Domain Reflectometer (TDR)
A Time Domain Reflectometer (TDR) is required to perform these tests. Two potential TDRs for use with
these procedures are the:
l
Tektronics 1502, which has a range of 0 to 2000 feet with a 6 in resolution.
l
Tektronics 1503, which has a range of 0 to 50,000 ft with a 3 ft resolution
Setup your TDR cable tester as indicated in the following table.
Parameter
Setting
Power
On (or Out)
Return Loss (0 to 60 dB)
0 dB (or Sensitivity)
Return Loss (Fine)
0 dB (or Sensitivity)
Feet/Div (Red) (X10/X100)
X10
Feet/Div (50 to .5)
.5
Noise Filter
Out
Position & Fine
Base Line in Center
Intensity
As required
Focus
As required
Distance
000
Impedance 50 Ohms
Out
Impedance 75 Ohms
In
Impulse Width 100 nsec
In (or Short Pulse)
Impulse Width 100 nsec
Out (or Medium Pulse)
Impulse Width 1000 nsec
Out (or Long Pulse)
Cable Dielectric Solid Poly
Out
Cable Dielectric Foam Poly
In (or .79 Distance Cal)
Cable Dielectric Var
As is
Zero Ref (Set)
First Pulse on Left of Screen
0 dB Set
As is
Table 6.1 Time Domain Reflectometer (TDR) Setup
CAUTION
To ensure valid testing, please observe the following cautionary notes:
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