RECEIVER OPERATION
AVTM651070 Rev B Nov 2006
27
Signal Strength Adjusted for Depth (Current Measurement)
The receiver contains a feature that is very useful in identifying a target cable (the
cable that is connected to the transmitter) in a field of various conductors and/or
utilities. It is not unusual for the target cable to induce or to leak the transmitted
signal into nearby conductors through a common ground system. Consequently,
you can receive a stronger signal from nearby conductors close to the surface of
the earth than the signal from the target conductor buried deeper. You will find
two or more paths and you must somehow determine which is the target
conductor. By using the current measurement feature of the receiver, you can
determine the amount of transmitted AF or RF current flowing on each
conductor. The highest current flow always indicates the target conductor.
To measure the current flow in each cable in the congested area, locate the path
of the cables. Mark these paths as accurately as possible (Refer to the sections on
Peak Mode Locating and Null Mode Locating). Place the receiver vertically over
one of the conductor paths and rest the foot of the locator on the ground. While
holding the receiver vertically, press and release the CURR button. When the
meter changes from a thermometer-type display to a bar-type display, hold the
receiver steady until the measurement stabilizes. The blinking bar indicates the
current level on the cable, adjusted for depth. Next, move to the second cable
and repeat the measurement. Again, the blinking bar will show the current level
on the cable. To help you remember the previous reading, it is shown as a solid
bar. The higher of the two readings will represent the target cable.
NOTE:
If the display reads
“
Err
”
during a current measurement, the receiver
has detected a condition that could produce inaccurate readings. Errors
can result when conductor signal current flow is too low. Check the
transmitter hookup and the far end access point for loose connections.
This problem can be identified when you need a high gain setting (80 or
greater on the bar-graph display).
The receiver may also be detecting adjacent cables or it may not be
positioned directly over the target conductor. Verify that the target
conductor path is accurate before measuring the current again. If at
anytime the display reads
“
CAL,” contact the factory for further
information.
Summary of Contents for L1070
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