SR50AT-Series Sonic Ranging Sensors
7
7.1 Sensor Mounting
7.1.1 Beam Angle
When mounting the SR50AT, the sensor’s beam angle needs to be considered.
Mount the SR50AT perpendicular to the intended target surface. The SR50AT
has a beam angle of approximately 30 degrees. This means that objects outside
this 30-degree beam will not be detected nor interfere with the intended target.
Any unwanted target must be outside the 30-degree beam angle.
Determine the required clearance for the beam angle using the following
formula and FIGURE
Clearance Radius formula:
(
)
CONE
0.
=
CONE
height
radius
268
Where,
CONE
height
= the distance to base (Section
(p. 7)
)
CONE
radius
= clearance radius in the same measurement units as the CONE
height
FIGURE 7-1. Beam Angle Clearance
7.1.2 Mounting Height
Mount the SR50AT so that the face of the transducer is at least 50 cm (19.7 in)
away from the target. However, mounting the sensor too far from the target can
increase the absolute error. For example, if your sensor is measuring snow
depth in an area that will likely not exceed 1.25 m (4.1 ft) then a good height to
mount the sensor will be 1.75 to 2.0 m (5.74 to 6.56 ft). Mounting the sensor at
a 4 m (13.1 ft) height can result in larger snow depth errors.
7.1.2.1 Reference Point
The front grill on the ultrasonic transducer is used for the reference for the
distance values. Because of the difficulty of measuring from the grill, most
users measure the distance from the target to the outer edge of the plastic
transducer housing (FIGURE
), and then add 8 mm (0.3 in) to the measured
distance.
