6
Adjustment of field strength level (Field)
NOTE: Univox 1kHz_pulse�wav or itu�wav test signal should be used for adjustment of field
strength level� A continuous sine wave is not recommended since the loop driver’s AGC
might decrease the level�
1� Activate the audio file 1kHz_pulse�wav�
2� Adjust the input level according to the driver’s manual�
3� Set the TONE (filter) switch to the NORM position (8)�
4� Set the RANGE switch to HI position (7)�
5� Hold the meter in a vertical position and adjust the field strength level until
0dB (400mA/m) at the listening height is achieved� (A representative reference
measurement position is midway between the center of the loop and the loop
perimeter�)
6� Confirm that the field strength level does not vary more than ±3dB within the listening
area�
System commissioning
1� Connect the actual signal source/s, preferably speech, and adjust the input level
according the loop driver’s manual, (if the primary sound source is unavailable,
haspeech�wav or itu�wav audio files can be used)�
2� Set the TONE (filter) switch to the NORM position (8)�
3� Set the RANGE switch to HI position (7)�
4� Hold the meter in a vertical position at the listening height�
5� Measure the field strength and verify that the highest peak reaches 0dB (400mA/m) by
observing the highest reading� Confirm that the field strength variation within the room
is within ±3dB�
6� Check that the sound quality (clear sound with no distortion) is acceptable by listening
to the sound of the loop through the monitor headphones at a comfortable volume�
