Size Of The Infrared Field To Be Planned - Beyerdynamic IRIS Notice D'utilisation

IRIS – Iris EF Digital Infrared Radiator
36

4.2.2 Size of the infrared field to be planned

The radiator emits a field of light in the shape of a cone. In other words, as the distance increases so,
too, does the diameter of the emitted light field until it exceeds a limit where the IR power is no longer
adequate for audio reception with a signal-to-noise ratio of better than 40 dB. This means that, with
a larger range, it is also possible to illuminate a larger area. When the range is reduced (because more
channels are transmitted), the conical field of light (and hence also the illuminated area) will be smaller.
The size of the field that can be illuminated depends on the range of the radiator, and this decreases the
more channels that are transmitted. To increase the range, the signal has to be transmitted by using
additional radiators.
To double the distance, four times the installed radiator power is required. There is a geometric relation
between the radiator power and the distance, because the light intensity decreases in proportion to the
square of the additional distance from the light source.
Rectangular coverage
The number of infrared radiators actually required can only be determined by performing a practical
test, however, "rectangular coverage" can also be very useful.
Figures explain what "rectangular coverage" is. We see that "rectangular coverage" is smaller than the
total coverage.
Note: in figure 2, the deviation X is negative and the rectangular coverage really is larger than the
actual coverage.
Fig. 1 Fig. 2