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3 Using the vLoc3 Series Receivers
3. Using the vLoc3 Series Receivers
3.1 Passive Locating
NOTE
The compass indicator is not active during the passive location.
Passive locating refers to the process of detecting signals that naturally occur on pipes and cables. These tend to fall into two
categories, radio signals and power signals.
Radio signals
- low-frequency radio transmitters create radio signals. These are used for broadcasting and communications
and are positioned throughout the world. As the frequencies are very low, the signals tend to penetrate and hug the Earth's
curvature. When the signals cross a long conductor such as a pipe or cable, the signals are re-radiated. It is these re-radiated
signals that the Radio mode can detect.
Power signals
- are created by mains power running in the supply cables. These signals are 50 or 60Hz depending on the
country. For instance the UK is 50Hz power while the USA is 60Hz. When electrical power is distributed throughout the network
some power finds its way back to the power station via the ground. These stray currents can jump onto pipes and cables and
also create power signals. Note that there has to be an electrical current flowing to create a detectable signal. For instance, a
live cable that is not in use may not radiate a detectable signal. Also a very well-balanced cable, i.e., the same current flowing in
live and neutral, will cancel out and may not create a signal. In practice this is unusual as there are usually enough imbalances
in the cable to create a good detectable signal.
3.1.1
Detecting Power Signals
1. Use the “
f
” button to put the vLoc3 receiver into the Power mode. Notice that the antenna mode indicator will be showing
Peak or Omni Peak as these are the only options in the passive modes.
51.6
Power 50
40dB
2. Hold the vLoc3 receiver vertically and away from the likely position of other cables or pipes.
3. Adjust the sensitivity using the “+“ and “-“ buttons so that the bar graph reading is just starting to show some movement.
Note that the compass feature is not available in the Power or Radio modes.
