Appendix B: Operator Performance Checks
1502C MTDR User Manual B–11
Jitter is the uncertainty in the timebase. Its main effect is that the waveform
appears to move back and forth a very small amount. If the jitter is too great, it
will affect the repeatability of very precise distance measurements.
1. Set the VERT SCALE less than or equal to 1.0 mρ/div.
2. Watch the leading edge of the pulse move and verify that this movement is
less than five pixels, or < 0.02 ft (0.006 m).
O
F
F
O
F
F
O
F
F
O
N
ac –1.624 ft
Jitter
Figure B–16: Jitter Apparent on Leading Edge of Incident Pulse
Using the Max Hold function (accessed in the Setup Menu, Acquisition Control)
can simplify your observation of jitter. Max Hold allows you to observe the
accumulated jitter without having to stare continuously at the display.
O
F
F
O
F
F
O
F
F
O
N
ac –1.624 ft
Accumulated
Jitter
Figure B–17: Jitter Captured Using Max Hold
8. Jitter Check