System Technology; Ir Radiation; Signal Processing; Quality Modes - Bosch INTEGRUS Installation And Operating Manual

INTEGRUS | Installation and Operating Manual | System description and planning

1.2 System technology

1.2.1 IR radiation

The Integrus system is based on transmission by mod-
ulated infra-red radiation. Infra-red radiation forms
part of the electro-magnetic spectrum, which is com-
posed of visible light, radio waves and other types of
radiation. It has a wavelength just above that of visible
light. Like visible light, it is reflected from hard sur-
faces, yet passes through translucent materials such as
glass. The infra-red radiation spectrum in relation to
other relevant spectra is shown in figure 1.2.
%
100
75
1
50
25
4
2
0
400 500 600
1 Daylight spectrum
2 Sensitivity of the human eye
3 IR radiator
4 Sensitivity of IR sensor
5 Sensitivity of IR sensor with daylight filter
Figure 1.2 Infra-red radiation spectrum in relation to other
spectra

1.2.2 Signal Processing

The Integrus system uses high frequency carrier signals
(typically 2-8 MHz) to prevent interference problems
with modern light sources (see section 1.3.2). The digi-
tal audio processing guarantees a constant high audio
quality.
Audio
Channel
4x
Audio
Channel
Figure 1.3 Overview of the signal processing (for one carrier)
Bosch Security Systems | 2003-02 | 3122 475 22011en
5 3
700 800 900 1000 nm
A/D Conversion
& Compression
4x
A/D Conversion
& Compression
The signal processing in the transmitter consists of the
following main steps (see figure 1.3):
1. A/D conversion - Each analogue audio channel is
converted to a digital signal.
2. Compression - The digital signals are compressed
to increase the amount of information that can be
distributed on each carrier. The compression factor
is also related to the required audio quality.
3. Protocol Creation - Groups of up to four digital
signals are combined into a digital information
stream. Extra fault algorithm information is added.
This information is used by the receivers for fault
detection and correction.
4. Modulation - A high frequency carrier signal is
phase-modulated with the digital information
stream.
5. Radiation – Up to 8 modulated carrier signals are
combined and sent to the IR radiators, which con-
vert the carrier signals to modulated infra-red light.
In the IR receivers a reverse processing is used to con-
vert the modulated infra-red light to separate analogue
audio channels.

1.2.3 Quality modes

The Integrus system can transmit audio in four differ-
ent quality modes:
• Mono, standard quality, maximum 32 channels
• Mono, premium quality, maximum 16 channels
• Stereo, standard quality, maximum 16 channels
• Stereo, premium quality, maximum 8 channels
The standard quality mode uses less bandwidth and
can be used for transmitting speech. For music the pre-
mium quality mode gives near CD quality.
Protocol Creation
& Modulation
en | 2
Carrier (to IR Radiators)