Maintenance and service channel.

The ternary symbols M1 and M2 represent non-

scrambled data that can be transmitted at a rate

of 1 kBaud. Those symbols are used for various

purposes:

- Maintenance Channel (control test loops

(LT

→ NT) and frame errors (LT → NT)

- Service channel (transparent user data and

transmit messages from NT to LT)

Encoding.

The encoding of a binary bit stream is made such

that 4 binary bits correspond to 3 symbols of ter-

nary symbol stream. The encoding follows the

rules of modified monitoring state 43 (MMS43).

COMMAND / INDICATE CHANNEL (A bits)

Command/Indicate codes are define depending on the mode selected (LT or NT).

NT mode COMMANDS (DIN)

ACT

1 0 0 0

Activate.

Layer 1 is activated at the UK0 interface starting with a ’wake-up’ signal INFO

U1W, followed by INFO U1A during synchronization and closed by INFO U1

when synch is gained.

AW

0 0 0 0

Awake.

Set the module interface from the power-down to the power-up state. No signal

is emitted at UK0 interface. Even DIN pin pulled LOW can have the same effect.

DC

1 1 1 1

Deactivation confirmation.

The module interface is deactivated. The transmitter is disabled but the receiver

is still enabled to recognize an awake signal. THe UIC is set in power down

state.

RES

1 1 0 1

Reset.

Reset the UIC to the initial state.

SY

1 1 0 0

Synchronize.

Drive the UIC in connect through from module interface to line interface.

Remark: Executing the command RES (1101) is functionally equivalent to pulling the RESETN pin (6)

LOW, with one exception:

a) RES command set pin DISS to HIGH (+5V)

b) pulling RESETN LOW set pin DISS to LOW (0V).

NT mode INDICATION (DOUT)

ACT

1 0 0 0

Activate.

The synchronous state of the receiver is reached.

DC

1 1 1 1

Deactivation confirmation.

The transmitter is disabled but the receiver remains enabled to detect awake

signals at UK0 UIC is set in power down state.

DEAC

0 0 0 0

Deactivate.

A request to deactivate INFO U0 has been detected.

CT

1 1 0 0

Connection Through.

The UIC is fully activated.

CTL2

1 1 1 0

Connection through with loop 2.

A loop 2 command has been detected at UK0.

L2

1 0 1 0

Loop 2.

Synchronization has been reached during a Loop 2 activation procedure.

RSYN

0 1 0 0

Resynchronization.

The receiver has lost framing and is attempting to resynchronize.

STU2071

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