Testing Times August 2010

C-TEC has launched a new test kit specifically designed to simplify the setup of an induction loop system and ensure its compliance with EN 60118-4 (the updated European Standard for Magnetic field strength in audio-frequency induction loops for hearing aid purposes).

Our FPROK test kit trades at £305.00 and includes a handheld Fosmeter Pro induction loop tester (pictured right), an MP3 player c/w pre-loaded test tones and a set of headphones. Easy-to-follow instructions and blank test certificates are also provided.

Key features

The Fosmeter Pro is a 400mA magnetic field strength meter and loop listener, complete with circuitry for measuring background noise, frequency response and metal compensation. It includes:-

• A digital LCD display with a user-friendly interface to simplify testing.

• Two 'soft' buttons that dynamically change their functions to suit the menu options being accessed.

• Battery low indication and an auto-power off function that kicks in after 10 minutes of Fosmeter inactivity.

• A 3.5mm headphone jack socket allowing users to listen to the loop signal using a set of HEAD1 headphones (supplied in FPROK kit).

The unit is powered from a 9V PP3 battery (provided) and is supplied in a protective canvas carrying case.

About induction loop testing

EN 60118-4 (2006) recommends the minimum magnetic field strength of an AFILS system over a "covered area" should be 400mA RMS per metre. The most efficient way of ensuring this requirement is met is to measure the magnetic field strength of a steady output from the AFILS amplifier. Unlike music or speech (both of which provide a variable sound output from which it is virtually impossible to obtain an accurate RMS reading), a sine wave has a consistent level and frequency. When fed into an AFILS system, a sine wave therefore gives a constant magnetic field strength, which can be easily and accurately measured using the Fosmeter Pro. EN 60118-4 also recommends tests are carried out on background noise and frequency response.

Clearly graphed and easy-to-understand test results

The Fosmeter Pro's test results are typically shown on the unit's LCD, as per the examples below.

Fosmeter Pro Test Menus

The tests that can be carried out using the Fosmeter Pro include:-

Field Strength test: Detects a pulsed 1kHz signal in accordance with EN 60118-4, calibrated at 400mA/m = 0dB L.

Background Noise test: Advises if the signal is acceptable, tolerable or too high in accordance with EN 601184.

Frequency Response test: Detects 100Hz, 1kHz and 5kHz in accordance with EN 60118-4. All three frequency readings are displayed on the same screen allowing you to tell at a glance if the setup is within the +/- 3dB L required by the standard.

Metal Compensation test: This test goes beyond the scope of EN 60118-4 but adheres to the 3rd octave frequency spectrum advised in the standard, measuring 1kHz through 8kHz. For use with amplifiers with metal compensation controls/functions.

Subjective listening test: Allows the installer to listen to the quality of the audio signal using the 32 ohm headphones (supplied) - a vital component of any AFILS test regime. Speech and music tracks are also provided on the supplied MP3 player to help installers ensure the system delivers the best possible audio signal.

One FPROK kit (plus ancillaries such as MP3 player connection leads) is all it takes to ensure your loop installations comply with current British Standards. Can you afford not to carry one in your tool box?