Operation Manual

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9.1 How to place beacons
Avoid placing beacons on long sound-conducting objects
This is a very rare but may happen in some special circumstances.
The best practice is to place beacons (stationary and mobile) in places that would
not result in the transfer of ultrasound energy from the beacon’s board/case directly
to the place it is attached via a medium other than air. For example, solid attachment
of a beacon to a long horizontal metal tube may result in the following:
- Sound emitted from the beacon propagates directly to the metal tube
- Propagation losses inside metal are much smaller than in the air
Moreover, the tube may act as a low-loss waveguide
- If the tube is solid enough and long enough, there may be a weird effect
where the receiving beacon receives the signal sooner than expected, i.e.,
sooner than the distance divided by the speed of sound in air. That
happens because the speed of sound in metal is much higher than the
speed of sound in the air. The ultrasound signal may even look stronger
than the real signal propagated through the air due to the lower amount
of losses of ultrasonic in metal than in the air
- It is good practice to place beacons on something relatively soft or
something that does not conduct sound
Place beacons in a way that provides the proper ultrasonic coverage. It must
be one beacon in the line of sight of minimum 2 beacons. Try to locate them
under ceilings to avoid shadows, walls etc.
- Optimal settings for stationary beacons in small and big rooms
- Use 30–50 ultrasonic pulses for larger places and the default 5 pulses for
smaller places
- Optimal settings for noisy environment
There are several ways to reduce impact:
- Mobile beacons can be placed very close to the source of noise without
harm, but stationary beacons should be placed further from the noise
because they are receiving the ultrasound, whereas the mobile beacon is
emitting the ultrasound.