Topcon Paver System 5 - Sonic Tracker and Temperature Changes

Paving Principles & Control Methods
Topcon Paver System Five Operator’s Manual
2-22
Sonic Tracker and Temperature Changes
Since temperature affects the speed of sound, the tracker
has a built in temperature sensor for applications with
gradual temperature changes such as on graders or dozers.
In paving applications you can get a more dramatic and
rapid change in air temperature. To compensate for these
variations a temperature bail is positioned below the
tracker.
When the Sonic Tracker’s transducer emits a sound wave,
the tracker records the time to the bail and continues to
listen for the grade reference. If a temperature variation
occurs, such as heat off a freshly paved mat, a difference in
time to the temperature bail is recorded. The correction for
the speed of sound is then applied to the grade reference
signal, preventing a change in mat depth. The tracker
corrects for temperature variations with every sound wave,
39 times per second. Figure 2-24 illustrates this concept.
Figure 2-24. Working with Sonic Trackers and Temperature Changes
S onic T racker II S onic T racker II
STOPWATCH
Temperature Bail
Target Reference
On Grade
T
arget Reference
STOPWATCH
Temperature Bail
Heat Induced
Target Error
On Grade
Heat Induced
Target Error
Wind Blown Heat
Off of
Freshly Paved mat