4
X
E1/G.703 P
LESIOCHRONOUS
M
ULTIPLEXER
O
PERATING
M
ANUAL
IOA77-1F
10
May 2007
3.3 Test loops
TM-77.1 and MD-77.1 device software enables closing a loop on E1 electric interface
and optical interface in the direction to and from the device. Concerning E1 interface, both loops
are closed at the same time. The figure below shows possible loops. A loop number is consistent
with the number used in the device software.
E1 port
E1 port
E1 port
E1 port
Optical por t
1
Demux
Mux
Figure 6.
Loops
3.4 Clock
transfer
TM-77 and MD-77 devices are based on a plesiochronous multiplexer compliant with ITU-
T G.742 standard. 2Mbit/s signals received on G.703 E1 electric interfaces are transmitted
separately. E2 linear optical interface collective signal clock is also separate from the clock
signals generated in E1 interface. The requirement is that the clock signal frequency restored on
E1 interface must be in accordance with ITU-T G.703 recommendation (2048 MHz
±
50ppm).
