Tektronix 1503C, Руководство пользователя, Страница: 51 / 128

Operator Tutorial
1503C MTDR User Manual
2–9
CABLE LENGTH SUGGESTED PULSE SUGGESTED ft/div
0 to 100 ft 2 ns 10 ft/div
51 to 500 ft 10 ns 50 ft/div
501 to 5000 ft 100 ns 500 ft/div
5001 to 50,000 ft 1000 ns 5000 ft/div
Noise
On a longer cable, “grass” might appear on the displayed waveform. This is
primarily caused by the cable acting as an antenna, picking up nearby electrical
noise.
1. Set the 1503C front-panel controls:
CABLE 10-ft cable
IMPEDANCE 93
NOISE FILTER 1 avg
VERT SCALE 0.00 dB
DIST/DIV 1 ft (0.25 m)
Vp .84
PULSE WIDTH 2 ns
n o
POSITION 50.0 ft
2. Attach the 50 terminator to the end of the test cable using the female-to-fe-
male BNC adaptor (both of these items are supplied with the instrument).
3. Increase VERT SCALE to 50 dB. Use the
n
o
POSITION control to keep the
waveform on the display. As the VERT SCALE setting increases, there will be
noise in the form of a moving, fuzz-like waveform with a few random spikes.
O
N
ac 50.00 ft
O
F
F
O
F
F
O
F
F
Figure 2–14: Noise on the Waveform.
4. Turn the NOISE FILTER control clockwise to 8. This will average out much
of the noise.