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Calibrating Induction Loop Systems to IEC 60118-4:
2006 Standards

Frequency response: 100-5000Hz ±3dB relative
to 1000Hz
Field strength: 400mA/m peak response
“Listening area” has been replaced with “listening volume”, i.e. listening
height has to be integrated into the specification. This means that the
magnetic field should be homogenous (±3dB) within the listening area and
at a stated minimum and maximum height approximating seated and standing
positions, for example 1.2m (seated) and 1.7m (standing).
Specified reference level: 400mA/m=0dB. A certifiable loop system must
achieve 400mA/m in program peaks.
Background noise is measured with the Field Strength Meter (FSM) in
A-filter position. The following is valid for the signal/noise (S/N) ratio
relative to 400mA/m=0dB:
- 47dB S/N ratio is desirable with loop amplifier connected
- If S/N ratio is lower than 32dB it should be reported and measures to
overcome the problem discussed with the loop installer/manufacturer
- For transitory listening (for example across-the-counter systems) a S/N
ratio down to 22dB can be accepted
Before an induction loop system is permanently installed, we recommend: - Environmental electromagnetic noise should be checked with the venue’s
lights and all electrical systems turned on.
- The loop wire should be temporarily taped or tacked in place and the
system fully tested before performing final installation.
- To check whether the loop system is interfering with audiovisual
systems, the venue’s audio & video systems should be on when testing the
loop.
- If electric guitars are used, they should be checked during the
pre-installation loop test in order to determine if their magnetic pickups
are sensitive to the planned loop location. For installation guidelines,
please click here.
Please note:
- We have many satisfied customers who simply use our Induction Loop
Receiver (included with the Satellite III) to set up their systems. The
receiver provides a gross visual LED indication of proper field strength
and the installer may check sound quality and noise using the supplied
headphones.
- In order for a looped site to be properly certified as meeting
international standards, a calibrated field strength meter kit, such as
our FSM Loop Test Set must be used.
Back to Induction Loop Assistive
Listening
Systems' List, click here.

E-mail
Oval Window Audio Today
If you have any questions about calibrating induction
loop systems,
simply e-mail us directly. One of our representatives will get back to
you promptly. Just e-mail your message to info@ovalwindowaudio.com
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