Velleman VTUSD Manuel D'utilisation page 4

Ordinarily it is not possible to measure through doors and windows, however, depending on how close your VTUSD
is to the opening, you may obtain satisfactory results by making repeated measurements at varying angles and
elevations until a correct estimate is achieved.
In fig. 2 the distance to the step ladder will be measured instead of the wall. The VTUSD requires a clear view within
a cone of ± 7°.
Ensure that your body does not enter this ±7° cone as shown as in fig. 3.
When measuring long distances or narrow spaces the ±7° of ultrasonic pulses will touch the walls and/or ceiling
and/or floor. As shown in fig. 4 any projectors or recesses will return an ultrasonic echo and the VTUSD will indicate
the distance to the closest reflection ; which is the upper recess.
VTUSD VELLEMAN
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