Apex Digital Hera, Руководство пользователя, Страница: 21 / 32

21
ADDITIONAL FUNCTIONS WHEN USED WITH ARGOS
When connected to the Argos limiter, the Hera measures the
microphone signal and sends the appropriate commands to
the Argos, which can then reduce the sound pressure level if
necessary.
The Hera can also control the pink noise generator in the
Argos. Pink noise is used as a reference for calibrating the
Hera should it be necessary to take into account differences
in sound pressure level between the actual position of the
microphone and the position at which the authorities measure.
MICROPHONE DISTANCE COMPENSATION
The measurement microphone is often located where it cannot
be interfered with. Consequently there is a good chance that
the sound pressure level at the microphone will be different
from that on the dance floor, which is where the authorities take
their level measurements. To get round this problem the Hera
can calculate the difference and factor it into its measurements.
The calibration procedure is fully described in the “Installer
menu” section.
The graph above illustrates the principle of operation of the
logic outputs. In this example, the threshold has been set to
110 dB ( green line ), the warning time period to 30 seconds
( yellow lines ) and the cut-off time period to 1 minute ( red line ).
At 70 seconds, the music has exceeded the threshold and
the warning time period has commenced. The LEQ has been
computed over the following 30 seconds but the final result was
below the threshold. Therefore nothing happened.
At 126 seconds, the DJ exceeds the threshold once again, so
averaging the SPL level has commenced. 30 seconds later,
the Warning lamp has been switched on because the LEQ
value was over the threshold. So, at that time, the cut-off time
period starts counting.
The DJ has seen the warning and has directly reduced the
level, but unfortunately a few seconds later, he pushed the
volume up again. As a result, 1 minute later the LEQ value is
still higher than the threshold and the Alarm/cut-off relay has
been activated, cutting the mains electricity supply to the power
amplifier.