Rockwell Automation System Design for the Control of Electrical Noise - Manual (Page 94)

Publication GMC-RM001A-EN-P — July 2001
11-4 Measuring Noise Reduction Effectiveness
H-Field Sniffing Method
The H-field is the magnetic field inductively coupled to the probe.
Connect the scope probe ground clip to the probe tip forming a small
loop. Hold the loop close to potential victim wiring. The loop antenna
is sensitive to orientation, so test all three axes to determine the
maximum reading at each location.
Figure 11.2
Simple H-field probe
Direct Voltage Measurement Method
Direct voltage measurement methods exist for both AC and DC
circuits. Each category are described in the paragraphs below.
Measuring DC Circuits
Direct voltage measurements with respect to a known good ground
are made at chosen points in your DC circuit using a standard 1x
scope probe. Set signal coupling to AC.