Leica Ultra User Manual page 76

Null point method
Warning
Ultra, Locate Sonde Signal
Null point method is effective for locating deep sondes or for verifying the location of a
sonde.
a
b
1. Circle over approximate location.
2. Follow directional arrows to locate the null point.
3. The sonde is correctly located at peak signal between null points.
The depth reading may not indicate the real depth of the service, especially if the sonde is
lying at the base of a large diameter duct.
Precautions:
Always compensate depth reading for service size.
a) Directional arrows
b) Null point
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