RD4000 Locating System User Manual
Page 32
Rough depth calibration check
This check is a quick and easy way of verifying that the depth reading on the receiver is within acceptable limits.
It can be used if you are getting inaccurate depth readings from a cable or pipe for which you know the
approximate depth. Inaccurate depth readings could be the result of the receiver picking up a stronger signal
such as another cable or pipe running in close parallel to the target pipe or cable.
There are two ways of checking the calibration of the receiver in the field. Both methods require the use of a
transmitter:
Method 1
Refer to illustration 1
•
Place the transmitter on top of a non-metallic object,
such as a cardboard box, on the ground and away from any
buried lines. Switch the transmitter on, ensuring that no
accessories are connected and that the transmitter is in
induction mode. To reduce the effects of ground coupling
the transmitter, when it is placed on the box, must be more
than half a metre/18 inches above the ground
•
Hold the receiver with the blade horizontal and pointing
towards the front of the transmitter and approximately
five metres/16 feet from the front of the transmitter.
•
Switch the receiver on
•
Select the same induction frequency as is selected on the transmitter
•
Select sonde mode on the receiver.
Refer to illustration 2.
Move the receiver from left to right and when the maximum signal is obtained place the receiver on top of a
non-metallic object, such as a cardboard box, on the ground. Ensure that the blade is horizontal and
pointing towards the transmitter. To reduce the effects of ground coupling the receiver, when it is placed on
the box, must be more than half a metre/18 inches above the ground
•
Press the depth/current key on the receiver
•
Using a tape measure, measure the distance from the base of the receiver to the centre of the transmitter
•
Compare this reading with the depth reading on the receiver.
The receiver can be considered accurate if the difference between the depth reading on the receiver and the
distance measured with the tape is less than 10%.
Method 2.
1.
Apply a signal to a cable or pipe of known depth
2.
Locate the cable or pipe and press the depth key
3.
Compare the depth reading on the receiver with the actual depth.
5M
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