Bosch INTEGRUS Specifications download pdf (Page 8)

2.2.2 Signal Processing

The Integrus system uses high frequency carrier signals

(typically 2-8 MHz) to prevent interference problems with

modern light sources (see section 2.3.2). The digital audio

processing guarantees an constant high audio quality.

The signal processing in the transmitter consists of the

following main steps (see figure 2.3):

1. A/D conversion -Each analogue audio channel is con-

verted to a digital signal.

2. Compression - The digital signals are compressed to

increase the amount of information that can be dis-

tributed on each carrier. The compression factor is also

related to the required audio quality.

3. Protocol Creation - Groups of up to four digital sig-

nals are combined into a digital information stream.

Extra fault algorithm information is added. This infor-

mation 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 convert

the carrier signals to modulated infra-red light.

In the IR receivers a reverse processing is used to convert

the modulated infra-red light to separate analogue audio

channels.

Figure 2.3 Overview of the signal processing (for one carrier)

2.2.3 Quality modes

The Integrus system can transmit audio in four different

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 premium

quality mode gives near CD quality.

A/D Conversion

& Compression

A/D Conversion

& Compression

Audio

Channel

Audio

Channel

Protocol Creation

& Modulation

Carrier (to IR Radiators)

2.2.4 Carriers and channels

The Integrus system can transmit up to 8 different carrier

signals (depending on the transmitter type). Each carrier

can contain up to 4 different audio channels.The maxi-

mum number of channels per carrier is dependent on the

selected quality modes. Stereo signals use twice as much

bandwidth as a mono signals, premium quality uses twice

as much bandwidth as standard quality.

Per carrier a mix of channels with different quality modes

is possible, as long as the total available bandwidth is not

exceeded.The table below lists all possible channel com-

binations per carrier:

Channel quality

Mono Mono Stereo Stereo Bandwidth

Standard Premium Standard Premium

44 x 10 kHz

21 2 x 10 kHz and

1 x 20 kHz

212 x 10 kHz and

1 x 10 kHz (left) and

1 x 10 kHz (right)

11 1 x 20 kHz and

1 x 10 kHz (left) and

1 x 10 kHz (right)

22 x 10 kHz (left) and

2 x 10 kHz (right)

22 x 20 kHz

11 x 20 kHz (left) and

1 x 20 kHz (right)

2.3 Aspects of infra-red distribution systems

A good infra-red distribution system ensures that all dele-

gates 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 consid-

ered when planning an infra-red radiation distribution

system. These are discussed in the next sections.

2.3.1 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 sensi-

tivity is tilted upwards at an angle of 45 degrees (see figure

2.4). Rotating the receiver will decrease the sensitivity.

8| System description and planning | Integrus Data brochure

Possible number of channels per carrier

1 2 3 4 5 6 7 8 9 10 11 12 13 ... 31 32

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Bosch INTEGRUS Specifications Page 8

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