BM-SCAN -
Magnetic field strenght meter
Page 12
English
5 - RMS/Peak signal level
When testing the background noise of a new building, turn on all lights, fans, sound
system and other electrical equipment as if the building were in use. If you certify an
installation, this test is performed without the hearing loop system being activated.
Walk in all areas where the loop system will be used, holding the meter upright at listening height.
The important reading will be MAX reading. However, it is important to look at the RMS reading.
If the MAX reading exceeds -32dBA (measurements above -32dBA will have a lower negative
number, for example -30dBA means there is more background noise than -35dBA), you will
need to specify areas where these noise levels are higher.
Notes and requirements of Standard 60118-4
The standard revised in 2004 notes that any background noise level below -47dBA will result
in excellent signal / noise, but levels below -32dBA are acceptable and meet the requirements
of the standard. If the background noise level is greater than -32dBA, building managers
should be informed so that the source of the interference found can be repaired or isolated.
The second mode is used to configure the audio loop signal level using a weighting filter. It is
very difficult to set the field strength to an average of -12dBA as it will vary depending on the
program used to configure the system. We will use the PEAK reading to confirm that our design
and equipment meet the specifications of the standard. Press key "B" to reset PEAK playback.
Once the loop system has been installed, create a limited pink noise (100Hz to 5KHz) of the loop
system bandwidth. Walk around the hearing area holding your meter vertically.
RMS / Peak
Weighted mode
A-RMS :
-12.5 dBA
MAX :
-0.2
4-2 How to test background noise?
5-1 Principle
