System Technology

1 INTEGRUS Tech STST/SEU-CO | |03.Mar.06 © Robert Bosch GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of

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Security Systems

System Technology

System Block Diagram

Infra-Red Radiation

Signal Processing

Audio Channel Quality Modes

Carriers and Channels

Audio Encoding and Quality

Transmission Protocol

I&O Manual



Security Systems

DCN Next GenerationDCN Next

GenerationIntegrusRadiatorIntegrusRadiator

Audio sourcesAudio

sources

Interpreters desks 6ch.Interpreters desks 6ch.

DCN systemDCN system

Diagram Digital Infra-Red Transmission System

Integrus

Trans-mitter

Up to 32

Channels

IntegrusReceiverIntegrusReceiver


IntegrusCharging equipment

IntegrusCharging equipment

IntegrusRadiatorIntegrusRadiator








Security Systems

Infra Red Radiation

Based on transmission by modulated infra-red radiation.

Has a wavelength just above that of visible light.

Like visible light, it is reflected from hard surfaces, yet passes through translucent materials such as glass.

Radiators are used to emission infra-red light with a wavelength of 870 nm.



Security Systems

Infra- Red spectrum in relation to other spectra

100

75

50

25

0

%

400 500 600 700 800 870 900 1000 nm

1

Daylight spectrumDaylight spectrum1

2

Sensitivity of the human eyeSensitivity of the human eye2

3

Intra-Intra- Red radiatorRed radiator3

4

Sensitivity of the Infra-Sensitivity of the Infra- Red diode at the receiverRed diode at the receiver4

5

Sensitivity of the Infra-Sensitivity of the Infra- Red diode at the receiver with daylight filterRed diode at the receiver with daylight filter5



Security Systems

Signal Processing

The Integrus system uses high frequency carrier signals (typically 2-8 MHz) to prevent interference problems with modern light sources.

The transmission system converts analogue audio signals to digital frequency modulated infra-red light.

The digital audio processing guarantees a constant high audio quality.

Receivers pick up the digital frequency modulated infra-red signal and convert it back to an audio signal for a headphone.

AudioChannel 01

Protocol Creation& Modulation

Protocol Creation& Modulation

Carrier(to IR Radiator)

A/D Conversion& CompressionA/D Conversion& Compression

4x 4x

A/D Conversion& CompressionA/D Conversion& Compression

AudioChannel 04



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Signal Processing main steps

1. A/D conversion - Each analogue audio channel is converted to a digital signal.

2. Compression - To increase the amount of digital information.

3. Protocol Creation - Groups of four digital signals are combined into one digital information stream. Fault algorithm information is added 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 infra-red radiators, which convert the carrier signals to modulated infra-red light.

6. De-Modulation – a reversed process is used in the IR receivers to convert the modulated infra-red light to separate analogue audio channels.



Security Systems

Audio Channel Quality modes

Up to four different audio channel quality modes:

1) Mono, standard quality, maximum 32 channels of 10kHz

2) Mono, premium quality, maximum 16 channels of 20kHz

3) Stereo,standard quality, maximum 16 channels of 2x 10kHz

4) Stereo,premium quality, maximum 8 channels of 2x 20kHz

The Standard quality mode uses less bandwidth and can be used for transmitting speech.

For music the Premium quality mode is advisable.



Security Systems


Up to 8 different carrier signals (depending on the transmitter type) can be transmit. Each carrier can contain up to 4 different audio channels.

The maximum number of channels per carrier is dependent on the chosen quality modes.

Per carrier a mix of channels with different quality modes is possible, as long as the total available bandwidth is not exceeded.



Security Systems


This table lists all possible channel combinations per carrier:

10kHz (R)

10kHz (L) 10kHz (L)10kHz (R)

20kHz 10kHz (L)

10kHz 10kHz 10kHz

10kHz (R)10kHz 10kHz 10kHz (L)

20kHz (L) 20kHz (R)

Channel Quality

10kHz (R)

20kHz 20kHz

10kHz

10kHz 10kHz 20kHz

Carrier

Mono SQ

Mono PQ

Stereo SQ

Stereo PQ



Security Systems


The data is digitally modulated onto the carriers. The modulation method used is DQPSK (Differential Quadrature Phase Shift Keying) with coherent detection at the receiver.

The information is carried by the phase changes.

2 .3 3 3 3 3 .6 6 7 4 .3 3 3 5 5 .6 6 7 6 .3 3 3 7f (M H z )

-3 d B

G u a rd b a n d

Carrier Allocation



Security Systems

All audio sent by the transmitter, is compressed by a sub-band APCM (Adaptive Pulse Code Modulation) encoder.

System Audio Performance

Measured from the audio input of an LBB4503 to the headphone output of an LBB4540

Audio frequency response:

Standard Quality mode………………... : 20 Hz to 10 kHz (-3 dB)

Premium Quality…………….…………. : 20 Hz to 20 kHz (-3 dB)

Total harmonic distortion at 1kHz … : < 0.05 %

Crosstalk attenuation at 4 kHz….…. : > 80 dB

Dynamic range……………………….. : > 80 dB

Weighted signal-to-noise ratio…….. : > 80 dB(A)

Audio Encoding and Quality

I&O Manual



Security Systems


Protocol and modulation technique :according to IEC 61603 part 7

Carrier structureEach carrier contains:

synchronization information

audio slots

data slot(s)

A Reed-Solomon RS coder is applied to protect the audio and data information for transmission errors.



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Audio slot A Audio slot B data RS paritySQ SQ

Audio slot A Audio slot B data RS paritySQ SQ

1 super frame

RS frame 0SYNC RS frame 1 RS frame 2 RS frame 3 RS frame 4 RS frame 5

With four Standard Quality channels



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Audio slot A Audio slot B data RS parityPQ

Audio slot A Audio slot B data RS parityPQ

With two Premium Quality channels

1 super frame

RS frame 0SYNC RS frame 1 RS frame 2 RS frame 3 RS frame 4 RS frame 5



Security Systems

System Technology

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System Technology

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