3
System Configuration
The A125 Noise Reduction board is configured by two jumper switches, (JMP1 and JMP2), shown in Table 1.
Jumper
Position
Position A
Position B
JMP1
* Separate microphone &
speaker at menu sign/post
OSM (speaker used as both a
speaker and a microphone at
the menu sign/post)
JMP2
* C960 Intercom
C5000 Intercom
Note:
* Indicates factory default settings
Table 1. A125 Jumper Settings
Mode Configuration
The A125 Noise Reduction board can be configured in several different modes by using DIP switch, SW1.
Following is a brief description of each mode and a DIP switch setting table.
Noise Reduction:
When DIP Switch number 1 ON the inbound microphone voice signal is digitized. On
digitized, the noise is digitally removed from the voice by the digital signal processor and converted back
to an analog voice signal. The analog voice signal is then sent to the microphone input of the intercom.
When DIP Switch number 1 is OFF the inbound microphone voice signal is digitized and converted back to
an analog voice signal without removing any noise. The analog voice signal is then sent to the microphone
input of the intercom.
Echo Reduction:
Used to reduce echo for full-duplex intercom configurations. Turn Echo Reduction OFF for
half-duplex intercom configuration.
Restaurant / Truck Stop Noise Reduction Level:
When DIP Switch number 3 is OFF, the board is set for
restaurant noise reduction level. When DIP Switch number 3 is ON, the board is set for truck stop noise
reduction level. This provides approximately 6dB more noise reduction with slightly more voice
dedegration.
Hi Frequency Equalization: When
DIP Switch number 4 is ON, the higher end frequencies are increased by
3dB. This should be set to the customer’s preference.
DIP Switch
Number
ON Position
OFF Position
1
* Noise Reduction ON
Noise Reduction OFF
2
* Echo Reduction ON
Echo Reduction OFF
3
Truck Stop Noise Reduction Level
* Restaurant Noise Reduction Level
4
Hi Frequency Equalization ON
* High Frequency Equalization OFF
5
Spare
Spare
6
Test Mode
(FACTORY USE
ONLY; DO NOT CHANGE)
* Normal Operating Mode
Note: *
Indicates Factory Default Settings
Table 2. A125 DIP Switch Settings
