Appendix D: Application Note
1502C MTDR User Manual D–9
Time vs. Long Distances, in Meters or Feet (any dielectric)
Distances to or between discontinuities farther apart than about three meters
(10 feet) can be found on the METERS and FEET scale. Use the sliding
ROUND TRIP TIME scale just below it and follow the same procedure as
above.
METERS FEET
ONE–WAY DISTANCE
TO OR BETWEEN FAULT, SPLICE,
CONNECTOR, LOAD, END, OR OTHER
IMPEDANCE DISCONTINUITY
20 30 40 50 6070 80
DIELECTRIC
CONSTANT
ROUND
TRIP
TIME
VELOCITY
FACTOR
1.0 1.5 2.0 3 4 5 6
1.0 .8 .7 .6 .5 .4
00ns 150ns 200ns 300ns 500ns 700n
Dieletric is Solid
Time = 300 ns
Velocity Factor = .66
Distance is
30 m or 99 ft
Polyethylene
100 15
Figure D–8: Dielectric Constant and Velocity Factor, Long Distance