At a Glance:
- Dynamic adjustment of public address levels depending on the surrounding noise level
- 4 independent sets with 1 microphone input per set
- Sets can be switched together in groups
- Supplies a fused operating voltage for measuring micro-phones
The module MI4M serves, in combination with up to four active microphone units, the dynamic adjustment of the public address volume to the surrounding noise level. The power supply of the measuring microphone (24 V) is supplied fused from the MI4M.
Application example for PA with MI4M
In order to record the surrounding noise a measuring microphone with built-in preamp is switched in. 1 measuring microphone can be connected per set in the module MI4M. The individual sets of the MI4M can be com-bined in groups.
The principle functions are illustrated in the following block diagram.
Block diagram MI4M
The pre-boosted noise signals are sent to the MI4M from the microphones mounted on the station platform over shielded 600 Ohm four-wire cables (2 wires LF, 2 wires power supply).
The signals are digitized after being prefiltered and adjusted in level. An adjustment value is calculated for the amplifier level control from the indi-vidual samples through a multi-phase averaging.
By providing signals over a larger period of time, it can be ensured that brief level peaks such as e.g. trains travelling through or brake noises do not lead to exaggerated level adjustments.
The adjustment response curve for the amplifier is specified through the configuration software ICS.
The LF level of the connected microphone determined by the module can be transmitted to the service PC and displayed in ICS.
2 integration times can be set.
Integration time "Quick” or “Slow” is selected in the configuration software ICS (depending on set).
A malfunction signal in the case of fuse outage can also be configured in the ICS. For this a measuring microphone must be set as terminal for the corre-sponding set.
The Front Plate Symbols and their Meaning:
|The System Blinker
Addressing from processor taking place
BUS output works as push-push operation with the system blinker
BUS input works as push-pull operation with the system blinker
LED illuminated: measuring taking place (depending on set)
LED off: Fuse triggered (depending on set)
|Operating Voltage:||48 V|
|Operating Voltage:||+/-5V (control)|
|Feeding Current (48V))||Max. 40 mA|
|Operational Current (+5V)||Max. 50 mA|
|Operational Current (-5V)||Max. 30 mA|
|Output Ub for Measuring Mic:||24 V / 20 mA (4x)|
|Temperature Range:||0 °C to 45 °C|