FlexGain PLEX - E&M unit

User’s manual FlexGain Plex, V2
Version 1.3 91 from 99
E&M unit.
Each of four interfaces provides the transmission of voice signals over two- or four-
wire scheme as well as the signaling processing over two input and two output lines. The
unit can be used to provide communication between different PBXs with E&M signaling
and to establish voice-frequency channels with two- or four-wire termination. The structural
scheme of an E&M unit is presented in Fig. 16.
CODEC
TX1
TX2
RX1
RX2
GND
ATS
-48В
M1
E1
M2
E2
M
I
C
R
O
C
O
N
T
R
O
L
L
E
R
Channel 1
Detector
Switch
Interface with the
basic module
Channel 2
Channel 3
Channel 4
Figure 13. Structural scheme of an E&M unit.
When the voice-frequency interface operates based on the four-wire scheme, the
input and output voice signals are transmitted separately over different physical pairs. The
two-wire scheme operates based on the differential system, which allows the input and
output signals to be transmitted over one pair. In this case, a pair is used through which in
the four-wire scheme the voice-frequency signal is received (with respect to the
multiplexer).