
MT9071
Preliminary Information
48
Figure 10 - E1 Synchronization State Diagram
N
ote 1. The basic frame alignment, signaling multiframe alignment, and CRC-4 multiframe alignment functions operate in parallel and are independent.
Note 2. The receive CAS bits and signaling multiframe alignment bit will be frozen when multiframe alignment is lost.
Note 3. Manual re-framing of the receive basic frame alignment and signaling multiframe alignment functions can be performed at any time.
Note 4. The transmit RAI bit will be one until basic frame alignment is established, then it will be zero.
Note 5. E-bits can be optionally set to zero until the equipment interworking relationship is established. When this has been determined one of the
following will take place:
a. CRC-to-non-CRC operation - E-bits = 0,
b. CRC-to-CRC operation - E-bits as per G.704 and I.431.
Note 6. All manual re-frames and new basic frame alignment searches start after the current frame alignment signal position.
Note 7. After basic frame alignment has been achieved, loss of frame alignment will occur any time three consecutive incorrect basic frame alignment
signals are received. Loss of basic frame alignment will reset the complete framing algorithm.
Note 8. When CRC-4 multiframing has been achieved, the primary basic frame alignment and resulting multiframe alignment will be adjusted to the basic
frame alignment determined during CRC-4 synchronization. Therefore, the primary basic frame alignment will not be updated during the CRC-4
multiframing search, but will be updated when the CRC-4 multiframing search is complete.
Note 9. 915 or more CRC errors in one second will reset the complete framing algorithm.
Yes
AUTC=1
&
CSYN=1
No
Yes
No
CRC4 Sync Acquired
(CSYNC = 0)
Continue Operating With
CRC to Non-CRC
(Note 7)
Out of CRC4 Sync
8ms timer
400ms timer
No
Send E1 E2 = TE
AUTC = 0
Out of MAS Sync
(MSYNCB = 1)
MAS Sync Acquired
(MSYNCB = 0)
Start Checking for Loss of
MAS Sync
Yes
No
No
Out of Basic Sync
(BSYNC = 1)
Search for Basic Sync
Yes
Basic Sync Acquired
(BSYNC = 0)
If ARAI=0 Send RAI = 0
Start Checking for Loss of
No
Search for MAS Sync
Verify as per G.732
Yes
Search for CRC4 Sync
Verify 2 Consecutive
multiframes
Yes
Start 400ms timer
Start 8ms timer
CRC4 Sync Acquired
(CSYNC = 0)
Parallel Search for
New Basic Sync
CAS
Multiframe Alignment Signal
CRC-4
Multiframing Path
CRC to CRC
(CRCIW = 1)
No
Search for CRC4 Sync
Verify 2 Consecutive
multiframes (Note 7)
Yes
Align to
New Basic Frame
Yes
No
Yes
Send
FAS Bit1 = TIU0
CRC to Non-
CRC
Multiframing
Path
CRC to Non-CRC
(CRCIW = 0)
Send CRC4 Framing
If ARAI = 1
Send RAI = TALM
If ARAI = 0
Send RAI = 1
If ARAI = 0
Send RAI = Flickered
If ARAI = 0
Send RAI = 0
If ARAI = 0
Send RAI = 0
Send E1 E2 as per G.703
(Note 7,8 & 9)
No