APPLICATION

The system has been developed and perfected for classroom use and activities involving musical and body rhythms.

Indeed, deaf children need an appropriate audible signal and whenever possible, they should be released from the constraint of being wired to equipment.

This is particularly important for very young children who must have unrestricted movement and be able to move freely about the classroom.

The microphone, which is linked to the SUVAG amplifier, picks up the audible signal and transforms it into an electrical signal, which is amplified –and filtered if necessary- by the unit.
This signal is conditioned in an electronic circuit called the " IR. DRIVER ", which is an extra circuit in the SUVAG unit. This signal is transmitted through cables to the " IR. Light EMITTERS ", fixed high up on the classroom walls.
Up to 10 IR. EMITTERS can be fitted, according to the size, configuration and characteristics of the classroom, so that it can be perfectly " illuminated ".
This light is not visible to the naked eye as its wavelength is in the infra-red range which the human eye cannot perceive.

The following points must be observed for the Receiver to function normally :

a) The lens with the diode, fitted to one of the headphone’s earpieces, must be illuminated by the IR. EMITTERS. The headphones will not function if, for example, the lens is covered with the hand.
b) The accumulators in the headphones must be charged. After using the headphones, the accumulators must be recharged regularly. For this purpose, the system is delivered with a " MULTIPLE CHARGER " : a unit which can charge up to 10 headphones at a time. An individual charger can also be used for one set of headphones.

The complete INFRA-RED system thus includes, for one class :

1) A SUVAG CT 10 IR. unit with a built in " IR. DRIVER" circuit.
2) Connecting cables with plugs for connection to the " IR. EMITTERS ".
3) " IR. EMITTERS " : 4 to 10, according to the volume and configuration of the classroom.
4) " IR. RECEIVER " headphones : 1 per child.
5) A " MULTIPLE CHARGER " for recharging the headphone accumulators.

The SUVAG unit fitted with an " IR. DRIVER ", can have " IR. EMITTERS " connected to it, and also, SIMULTANEOUSLY AND IF NECESSARY, a distribution box so that several headphones ou vibrators can be used. This can be useful for children for whom the IR. hedphones are not suitable.

In addition, the INFRA-RED system preserves the transmission of very low frequencies of the acoustic spectrum. The filter system chosen for the SUVAG is also fitted to the " IR. RECEIVER ".

The " MULTIPLE CHARGER " is fitted with an automatic device which, after a nominal charge time of 14 hours, moves onto a reduced charge setting so that headphones can be left to charge for several weeks with no danger of overloading or damaging the accumulators.

There is no limit to the number of children who can be fitted with " IR. RECEIVER " headphones.

TECHNICAL SPECIFICATIONS

Driver :

- Low frequency nominal input signal : 30 mV.
- Compression : from 30 mV to 5V ± 2 dB.
- Pre-emphasis : 50 µs.
- Sub-carrier : 90 kHz ± 2 kHz.
- Modulation : F.M.
- Deviation : ±25 kHz
- Output signal : 4 V.p.p.
- Frequency Range : 5 Hz - 12 kHz.
- DC supply for emitters : 34 V = max./1,3 A max.

Emitters :

- Metal casing : adjustable.
- Power supply : 34 V DC = max./0,11 A max.
- Emitting diodes : 8
- Angle of emission : 90° conical.
- IR. wavelength : 880 n m.
- Emitter ON/OFF indicator : LED.

IR. receiver headphones :

- Power supply : Cd Ni accumulator 6 x 1,3 V = /250 mAh.
- Squelch : built-in, automatic.
- De-emphasis : 50 µs.
- Reception angle : 110° conical.
- Frequency Range : 6 Hz – 11 kHz.
- Distortion : < 3 %
- Sound Pressure : 126 dB SPL max. adjustable by potentiometer.
- S/N ratio : strong IR. signal = 55 dB.
- Weight with accumulators : 515 g.