MT9079
receive span will not be masked on the transmit span
even though the maintenance channel has been
modified.
Fibre Interface
Figure 16 shows how the MT9079 can be employed
to a fibre optic transmission system. The MT9079
control bits COD1-0 must be set to 01 to select
Non-Return to Zero (NRZ) operation. NRZ data is
manchester encoded and converted to a light signal,
which is transmitted down the fibre optic cable. On
the receive side the light signal is detected and
converted to an electrical signal, which is passed to
a manchester decoder. The manchester decoder
generates the receive NRZ signal and a receive
clock.
The RxMF signal must be associated with the CRC-4
multiframe (control bit MFSEL = 1), and RxMF of the
receive trunk must be connected to TxMF of the
transmit trunk. The data delay time (DSTo to DSTi)
and the TxMF to RxMF delay must be equal.
Therefore, a m + 1 frame delay circuit is added to the
TxMF to RxMF connection (where: m is the delay in
basic frames through the Digital Cross-Connect
Matrix).
It should be noted that in the TxMF to RxMF
operation is only valid when the C4i/C2i input of
MT9079 devices is driven by a C4 clock signal.
4-280
MITEL [ MITEL NETWORKS CORPORATION ]
