Locating And Tracing A Sonde - SPX Radiodetection RD7000+ Operation Manual

7.4.5 Locating and tracing a sonde

Insert the sonde in the drain or duct access and locate
it while it is still just in view at the drain or duct entrance.
Hold the locator vertical directly over the sonde with
the antenna in line with the sonde. Adjust the locator
sensitivity so the bar graph reads between 60% and 80%.
The sonde radiates a peak field from the center of its axis
with a ghost signal at each end of the peak. Move the
locator a little way behind and then in front of the axis of
the sonde to detect the ghost signals. Finding the two
ghost signals positively confirms the locate. Reduce the
locator sensitivity to lose the ghost signals but still indicate
a clear peak response directly over the sonde. Locator
sensitivity is now set for tracing the duct or drain unless
the distance between sonde and locator changes.
Propel the sonde three paces along the drain or duct and
stop. Place the locator over the supposed position of the
sonde. Do not adjust the sensitivity level.
To locate a sonde:
1. Move the locator backwards and forwards and stop
when the bar graph indicates a peak. You can use the
LCD compass to orient the blade of the locator with
the direction of the sonde.
2. Rotate the locator as if the blade is a pivot. Stop
when the bar graph indicates a peak.
3. Move the locator from side to side until the bar graph
indicates a peak.
4. Repeat 1, 2 and 3 with the antenna vertical and
resting on or just above the ground. The locator
should then be directly above the sonde with the
antenna inline with it. Mark the position of the sonde
and its direction.
5. Propel the sonde a further 1 or 2 meters, pinpoint,
and mark the position. Repeat this pinpoint procedure
at similar intervals along the line of the drain or duct
until the survey is completed.
26 RD7000+ Operation Manual
Figure 7.6: Sonde deployment
Figure 7.7: Locating a sonde
Figure 7.8: Calculating sonde depth