Radiodetection RD7000 User Manual page 13

Locating sondes
Sondes are self-contained, battery powered transmitters that are useful for tracking
non-metallic pipes. The RD7000 PL, DL and TL can detect a range of sonde
frequencies, including those transmitted by flexisondes and the P350 flexitrax
(visit www.radiodetection.com for more information on other Radiodetection products).
To locate a sonde
1. Set up the sonde according to the sonde's user documentation. Make sure
the sonde is sufficiently powered for the duration of the survey; note the sonde's
operating frequency,
2. Deploy the sonde into the pipe or duct as required,
3. On the receiver, select the sonde frequency by pressing the ƒ key until the
desired frequency is displayed on the LCD and the sonde icon is visible,
4. Set the gain to approximately 60-80%,
A sonde radiates a peak field from the center of its axis with ghost signals at each side
of the peak. Move the receiver to one side and then along the axis of the sonde forwards
and backwards to detect the ghost signals.
Radiodetection recommends locating the ghost signals as finding them confirms the
position of the main peak. To lose the ghost signals, reduce the sensitivity of the receiver;
this should leave only the main peak signal detectable.
With the receiver sensitivity set as desired, propel the sonde along three or four meters
and stop. Place the receiver over the estimated position of the sonde and:
1. Hold the receiver vertically with the blade in line with the sonde,
2. Move the receiver backwards and forwards with the blade's orientation parallel
to the sonde,
3. Stop when the bar graph indicates a clear peak,
4. Rotate the receiver until the blade's orientation is perpendicular to the sonde,
stop when the bar graph indicates a clear peak,
5. Move the receiver from side to side until the bar graph indicates a clear peak.
When the receiver locates a peak signal, it will automatically calculate the depth of the
sonde. Observe the depth reading while moving the receiver from side to side; the
lowest reading will be the correct location.
Repeat each step in smaller increments with the receiver blade resting on or near the
ground. The receiver should now be directly above the sonde with the blade in line with
the sonde; mark this position.
Propel the sonde a further three to four meters along the pipe to pinpoint its location.
Mark the location as required. Repeat the procedure along the route at similar intervals.
Note, while tracking the sonde, altering the receiver's sensitivity is not required unless
the pipe's depth, or the distance between receiver and sonde changes.
crawler
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