IBM 5500 Operational, Installation, And Maintenance Manual page 115

Dm = t (µs) × 105.0 m/µs
For IBM Cabling System cable:
Df = t (µs) × 366.7 ft/µs
Dm = t (µs) × 111.8 m/µs
where: Df= the distance to the fault in feet.
Dm = the distance to the fault in meters
µs = microseconds
t = the time in microseconds from the start of the B-gate
pulse to the start of the reflected signal. To find t,
multiply the number of scope divisions by the B-sweep
time/div
Note: Pulse rise time increases on long cables. Measure from the point where
the reflected pulse just starts to change, as indicated by the arrows in Figure
44 below.
t (time in microseconds)
Figure 44: Pulse Rise Time
An Example of Measuring Distance:
The example in Figure 45 on page 116 is for a solid measuring distance, with
the B time/div set to 0.2 microseconds and the number of oscilloscope
divisions at 6.
Open Cable
55E1I021
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