Figure 23 – Sonde Locate: Equator
• Double-check the two Pole locations.
• Notice that the Measured Depth reading at the maxi-
mum Signal Strength location is reasonable and con-
sistent. 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.
It doesn’t matter whether you locate the Poles first, and
then the Equator, or the Equator first, and then the Poles,
or one Pole, then the Equator, and then the other Pole.
You can even locate the Sonde using just the Signal
Strength, and then verify your result with the Poles and
Equator. What is important is that you verify all the data
points, and mark the Sonde’s position where the signal is
highest.
Tilted Sondes
If the Sonde is tilted, one Pole will move closer to the
Sonde and the other farther away so that the Sonde lo-
cation no longer lies midway between the two Poles. The
Signal Strength of the nearer Pole becomes much
higher than that of the more distant Pole if the Sonde is
vertical (as it could be if it fell into a break in the line);
however, it can still be located.
If the Sonde is
vertical what is seen on the screen is a
single Pole at the point of maximum Signal Strength.
(The RIDGID Floating Sonde is designed to have a
Ridge Tool Company
14
NaviTrack
®
II
single Pole “visible” and is weighted to maintain the
Sonde on a vertical axis.
See Note below.)
It is important to realize that a severely tilted Sonde
can cause the Pole locations and the Equator to appear
offset because of the angle of the Sonde; but maximiz-
ing the Signal Strength will still guide to the best location
for the Sonde.
Floating Sondes
Some Sondes are designed to be flushed or to drift down
a pipe pushed by water flow. Because these Sondes
swing much more freely than a torpedo-shaped Sonde in
a pipe, they can be oriented any which way. This means
the Equator may be distorted by tilting, and the location of
the Poles may vary. The only guarantee of having located
a floating Sonde is maximizing the Signal Strength and
double-checking that the signal falls away on every side
of the maximum signal location.
NOTE! If a Sonde is moving, it may be easier to “chase”
a pole and then pinpoint the actual position of
the Sonde after the Sonde has stopped moving.
Measuring Depth (Sonde Mode)
The NaviTrack II calculates Measured Depth by com-
paring the strength of the signal at the lower antenna to
the upper antenna. Measured Depth is approximate; it will
usually reflect the physical depth when the mast is held
vertical and the bottom antenna is touching the ground di-
rectly above the signal source,
assuming no distortion is
present.
1. To measure depth, place the locator on the ground,
directly above the Sonde.
2. Measured Depth will be shown in the lower left hand
corner of the NaviTrack II’s display screen.
3. A Measured Depth reading can be forced by pressing
the Select Key during a locate.
4. Measured Depth will be accurate only if the signal is
undistorted.
Clipping (Sonde Mode)
Occasionally the Signal Strength will be strong enough
that the receiver will be unable to process the entire sig-
nal, a condition known as “clipping”. When this occurs a
warning symbol will appear on the screen. It means
that the signal is particularly strong.
NOTE! Measured Depth Display is disabled under
clipping conditions.
IMPORTANT! Remember that being on the Equator
does not mean one is over the Sonde.
Seeing two Poles aligned on the dis-
play is not a substitute for centering
over each Pole separately and mark-
ing their locations as described
above.
If the Poles are not visible, extend the search.
For best accuracy use the bubble level. The mast
MUST be vertical when marking the Poles and
Equator, or their locations will be less accurate!
