3
Background information
• The meter responds to program peaks� The PPM style of indicator was developed by
broadcasters to control the peak levels of audio signals and so prevent overmodulation
of the transmitters� The PPM meter allows the user to verify in real time that an AFILS
can provide sufficient field strength for good speech clarity�
• The monitor audio output is active on all range and filter combinations� The monitor
output frequency response is modified to emulate that of a typical induction loop
listener� This means that the person testing hears a similar signal to that to be heard by
a loop user�
• The meter is operated in the vertical plane so that is easy to read when held at the
hearing position�
• This meter is designed with high quality components for low noise and operates over a
very wide range of 54dB in two stages� The range in use is indicated by an LED as is a
low battery condition warning�
• Two measurement filter (tone) responses are provided� The FLAT setting is provided
only for measuring system frequency response in conjunction with an external signal
generator� For all other measurement the NORMAL setting is used�
• The meter is calibrated, traceable to International Standards� Annual checking of
calibration is advised�
Overview
1� LO range when lit*
2� HI range when lit*
3� 0dB=400mA/m
4� Headphone socket
5� Volume control
7� HI range for AFILS
signal strength
9� LO range for
background
magnetic noise
6� FLAT - AFILS
frequency response only
8� NORM - AFILS for
hearing aids
* The range indicator in use flashes when the battery is low�
