Aspects Of Ir Distribution Systems; Receiver Directional Sensitivity; Footprint Of The Radiator - Danish Interpretation Systems DCS 6000 User Manual

DIS
A good infra-red distribution system ensures
3.3

Aspects of IR distribution systems

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 Irradiation 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.
The sensitivity of a receiver is at its best when it
3.3.1

Receiver directional sensitivity

is aimed directly towards a radiator. The axis of
maximum sensitivity is tilted upwards at an
angle of 45 degrees (see Figure 3.2-C).
Rotating the receiver
sensitivity. For rotations of less than +/- 45
degrees this effect is not large, but for larger
rotations the sensitivity will decrease rapidly.
The coverage area of a radiator depends on the
3.3.2

Footprint of the radiator

number of transmitted carriers and the output
power of the radiator. The coverage area of the
RA 6025 radiator is twice as large as the
coverage area of the RA 6013. 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 3.3-A
and Figure 3.3-B. The radiation pattern is the
will decrease the
User Manual DCS 6000 Digital IR System rev H.docx
area within which the radiation intensity is at
least the minimum required signal strength.
Figure 3.3-A Total coverage area of RA 6013 & RA 6025 for 1
to 8 carriers
Figure 3.3-B Polar diagram of the radiation pattern for 1, 2, 4
The cross section of the 3-dimensional radiation
& 8 carriers
pattern with the floor of the conference venue is
known as the footprint (the white area in Figure
3.3-C to Figure 3.3-E).
This is the floor area in which the direct signal is
strong enough to ensure proper reception, when
the receiver is directed towards the radiator. As
shown, the size and position of the footprint
User Manual
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