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In the following block description, the new naming convention of the G.783 is reported. Refer to para. 3.3.4
on page 206 for details.
The G.A.#1 send and receive four 622 Mbit/s signal (data + clock) to/from the G.A.#5
The SPI can detect an external LOS from the input line .
The optical transmitter provides to the G.A. its status by Laser Failure signal.
The ALS algorithm is hardware implemented and the G.A. provides the Laser shut Down command
(LASER OFF).
On the front panel of the unit a push–button is available for manual laser restart.
TTF BLOCK (SPI, RST, MST, MSA)
This block performs the Transport Terminal Functions (sink on Input side, source on Output side) for the
STM–16 signal.
TTF block provides the T1 timing references at 2 MHz , derived from the STM–16 input signals
INPUT side : from line to MSP MATRIX
SPI (OSn/RSn_A_Sk) : it descramblers the incoming signal , counts the OOF and reveals the LOF
alarm.
RST (RSn_TT_Sk) : performs frame alignment detection (A1, A2) , regenerator section trace
recovery (J0) and mismatch detection, BIP–8 Errored Block count.
MST (MSn_TT_Sk) : performs BIP–24 errored block count, MS–REI recovery, MS–RDI and MS–AIS
detection. TSD is applied in case of MS–DEG (signal degrade), TSF is applied if MS–AIS is detected.
MSA (MSn/Sn_A_Sk) : performs AU4's pointer interpretation, LOP and AIS detection, pointer
justification. Sixteen MSA blocks are present.
Moreover the following functions are performed on the Input side :
SOH BYTE extraction (Rx side): DCC bytes (DCCR D1–D3 and DCCM D4–D12) are dropped and
serialized in a DCC frame. Two DCC frames are generated working in 1+1 protection.
TP byte insertion (Rx side) : since the cross connection functions are centralized , for protection
purpose TSD (Trail Signal Degrade) and TSF (Trail Signal Failure) are transmitted towards the two
MATRIX board.
K BYTES insertion and extraction (Rx side) : this block provides the in–band transmission of
K1,K2, bytes towards the MATRIX board. The bytes are extracted from the line when a TSF is
received and they are transmitted towards the two MATRIX board.
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