Aspects Of Infra-Red Distribution Systems; Directional Sensitivity Of The Receiver; The Footprint Of The Radiator - Bosch Integrus Installation And Operation Manual

18 en | Planning
4.2

Aspects of Infra-red distribution systems

A good infra-red distribution system ensures that all delegates in a conference venue receive
the distributed signals without disturbance. This is achieved by using enough radiators,
placed at well planned positions, so that the conference venue is covered with uniform IR-
radiation of adequate strength. There are several aspects that influence the uniformity and
quality of the infra-red signal, which must be considered when planning an infra-red radiation
distribution system. These are discussed in the next sections.
4.2.1

Directional sensitivity of the receiver

The sensitivity of a receiver is at its best when it is aimed directly towards a radiator. The axis
of maximum sensitivity is tilted upwards at an angle of 45 degrees (see Figure 4.3). Rotating
the receiver will decrease the sensitivity. For rotations of less than +/- 45 degrees this effect is
not large, but for larger rotations the sensitivity will decrease rapidly.
Figure 4.3 Directional characteristics of the receivers
4.2.2

The footprint of the radiator

The coverage area of a radiator depends on the number of transmitted carriers and the output
power of the radiator. The coverage area of the LBB 4512/00 radiator is twice as large as the
coverage area of the LBB 4511/00. The coverage area can also be doubled by mounting two
radiators side by side. The total radiation energy of a radiator is distributed over the
transmitted carriers. When more carriers are used, the coverage area gets proportionally
smaller. The receiver requires a strength of the IR signal of 4 mW/m2 per carrier to work
without errors (resulting in a 80 dB S/N ratio for the audio channels). The effect of the
number of carriers on the coverage area can be seen in Figure 4.4 and Figure 4.5. The
radiation pattern is the area within which the radiation intensity is at least the minimum
required signal strength.
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Installation and Operation manual
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