BildFunction and use of infrared transmission systems

How does an infrared audio transmission system work?

An IR audio transmission system consists of at least one transmitter and one receiver. The transmitter is connected to an audio source – to a microphone system, for example – and transmits the signals received in the form of infrared light impulses wirelessly to the receiver, which converts the light impulse received into electrical audio signals and feeds them into the reproduction device connected – into headphones, for example, or a teleloop for the inductive direct transmission to hearing aids.

HUMANTECHNIK assists with an all-round service.

Planning, project evaluation and installation of acoustic transmission systems often requires special know-how. Therefore we offer comprehensive consultation and service bundles for this area. From qualified information up to installation and setup, we assist you with our consultation service, so you can set up effective and professional transmission installments.

The transmission energy of infrared transmission systems spreads out in a roughly circular shape with a wide emission angle.

Fields of application

Apart from the home environment, in which the wireless reception of audio signals via infrared light has long since become a popular alternative to the corresponding radio-frequency transmission systems, this technology proves superior to all other transmission methods for certain large professional applications.

This applies in particular to venues and facilities, ...

... in which the confidentiality of the information exchanged there plays a decisive role, for example in courtrooms or conference rooms,..

and areas, ...

... in which several transmission systems are operated parallel to one another in neighbouring rooms, such as in multiplex cinemas or in living quarters in social facilities.

 

In addition, infrared audio transmission systems have proven valuable in schools and universities, in large auditoriums with partial signal cover­age or in city centres, in which there is a very high rate of radio-frequency emissions.

Advantages of infrared transmission technology

  • Infrared light signals cannot pass through walls, which reduces reception to the room in which the transmitter is installed.
  • Transmission is reliable and absolutely free of the interference caused by electromagnetic fields or structural elements in the building, such as metal reinforcements. In addition, these systems do not produce any electromagnetic emissions themselves.
  • Infrared transmission systems can be used easily in many different countries; an »obligation to register« them, similar to the allocation of radio licenses, is not required.

 

Coverage

While the range of systems designed for private use is limited to about 10 or 20 metres, high-powered infrared transmitters are able to provide coverage for much larger rooms.
The transmitters described in this product overview, for example, are able to provide coverage for up to 2600 m².

Other characteristics of infrared audio transmission systems:

  • Portable/mobile systems are available.
  • Multi-channel operation provides for flexible use, making it possible to simultaneously transmit several different languages, for example.
  • Receivers are compatible with TV listening systems for at-home use.

 

Other factors affecting infrared transmission technology:

  • The transmitter does not focus the emission of the infrared light impulses, i.e. it uses a very large transmission angle. As a result, there is generally no need for a specific »line of sight« between the transmitter and the receiver.
  • The signals do not only travel directly between the transmitter and the receiver, but are also reflected from the walls, cei­lings and floors. Nevertheless, pillars and furniture – depending on their size and position – can interfere with or even block reception under certain conditions.
    In any case, a technically correct, precise positioning of the transmitters is required for optimal signal coverage.
  • Light-coloured floor, wall and ceiling areas reflect infrared energy more strongly. This can increase the reception range.
  • Dark, low-reflection floors, ceilings and walls absorb the energy and can limit reception ranges as a result.
  • The carrier frequencies of 2.3 to 3.8 MHz (basic band) minimize the probability of interference resulting from powerful lighting. However, functional problems due to direct sunlight cannot be ruled out altogether.
  • In order to provide coverage for areas that exceed the maximum range of the individual transmitters, it is necessary to install several transmitters at different locations and connect them in parallel.*

 

*If the reception range is the main criteria for the application in this context, it is advisable to consider the use of a radio-frequency system as an alternative – also taking into consideration the cost factor.


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