Step 2: Pinpoint the Sonde
The Poles
should appear on either side of the maximum
signal point, an equal distance on either side if the Sonde
is level. If they are not visible on the screen at the point of
maximum Signal Strength, move from the maximum point
perpendicular to the dotted line (Equator) until one appears.
Center the locator over the Pole.
Where the Poles occur depends on the Sonde's depth. The
deeper the Sonde, the further away from it the Poles will be.
The dotted line represents the Equator of the Sonde. If the
Sonde is not tilted, the Equator will intersect the Sonde
at maximum Signal Strength and minimum Measured
Depth.
NOTE: being on the Equator does not mean that the locator
is over the Sonde. Always verify the locate by maximizing
Signal Strength and marking both Poles.
•
Mark the first Pole location found with a red triangular
Pole marker. After centering on the Pole, a double
line indicator represents how the Sonde is lying
underground, and in most cases also represents the
pipe's approximate direction.
•
When the locator gets close to a Pole, a zoom ring will
appear centered on the Pole.
•
The second Pole will be a similar distance from the
Sonde location in the opposite direction. Locate it in
the same manner and mark it with a red triangular
marker.
•
If the Sonde is level, the three markers should be
aligned and the red Pole markers should be similar
distances from the yellow Sonde marker. If they are
not, a tilted Sonde may be indicated. (See "Tilted
Sonde") It is generally true that the Sonde will be
on the line between the two Poles, unless there is
extreme distortion present.
Step 3: Verify the locate
•
It is important to verify the Sonde's location by
crosschecking
maximizing Signal Strength. Move the SR-20 away
from the maximum Signal Strength, to make sure that
the signal drops off on all sides. Make sure to move
the unit far enough to see a significant signal drop in
each direction.
•
Double check the two Pole locations.
•
Notice that the Measured Depth reading at the
maximum Signal Strength location is reasonable and
consistent. If it seems far too deep or too shallow,
recheck that there is an actual maximum Signal
Strength at that location.
•
Notice that the poles and the point of highest Signal
Strength lie on a straight line.
IMPORTANT! Remember that being on the Equator does
not mean one is over the Sonde. Seeing two Poles aligned
on the display is not a substitute for centering over each
Pole separately and marking their locations as described
above.
If the Poles are not visible, extend the search.
For best accuracy the SR-20 should be held with the mast
oriented vertically. The antenna mast must be vertical
when marking the Poles and Equator, or their locations
will be less accurate.
Ridge Tool Company
seekTech sR-20
the
receiver's
Figure 28: Sonde Locate: Equator
Tools For The Professional
TM
information
and