MT8910-1 Mitel Networks Corporation, MT8910-1 Datasheet - Page 6

• Manufacturer Part Number: MT8910-1
• Description: CMOS St-bus Family Digital Subscriber Line Interface Circuit
• Manufacturer: Mitel Networks Corporation

MT8910-1
Basic Frame Synchronization (BFS) is achieved
using the algorithm shown in Figure 5. The DSLIC
searches for the sync word or the inverted sync word
within the received data stream.
three consecutive synchronization patterns spaced
exactly 120 quats apart, the DSLIC declares terminal
synchronization by setting the bits of the Internal
State Indicator to 111 in Status Register 1. A loss of
synchronization is declared by the DSLIC when at
least one of the nine quats at the beginning of each
Basic Frame differs by more than one quantization
level for two consecutive frames.
A search for superframe synchronization will begin
only after Basic Frame sync has been found. The
DSLIC will declare superframe sync (SFS) on the
first occurrence of the properly spaced Inverted Sync
Word (ISW) once Basic Frame sync has been
acquired. The synchronized state is identified by the
9-8
Superframe
Frame
Information
Channels
Corresponding
ST-BUS
STATE : LOST
BFS
Valid
Valid
SW
STATE : SENSING1
BFS
STATE : SENSING2
BFS
One
One
SW
SW
2B + D 2B + D 2B + D
: 0
: 0
: 0
B11 B12 B13 B14
B7
Frame 1
Error in
SW
B6
B5
Figure 5 - Frame Synchronization State Diagram
Frame 2
B4
50 s
After detecting
B15 B16 B17 B18 B21
2B + D 2B + D 2B + D 2B + D
B3
Error in
SW
Figure 4 - Frame Structure
Frame 3
B2
> One-Level Error in SW
One Valid SW
B1
B0
Frame 4
1.5 ms
12 ms
status of internal state bits IS2, IS1 and IS0 found in
Status Register 1.
The DSLIC will lose superframe sync under three
conditions;
1)
2)
frames apart,
3)
Activation/Deactivation
The DSLIC has a complete activation/deactivation
state machine which allows the user to activate or
deactivate the link as per the requirements in the
B7
if the DSLIC loses basic frame sync,
if the ISW does not occur exactly eight basic
if the ISW is received when it is not expected.
B22 B23 B24 B25 B26
B6
Frame 5
B5
2B + D
B4
Frame 6
50 s
2B + D 2B + D
Valid
STATE : SYNC
BFS
SW
STATE : LOSING
BFS
Preliminary Information
B3
B2
: 1
: 1
Frame 7
B27 B28
B1
> One-Level
Error in SW
2B + D 2B + D
B0
Frame 8
D0
D1
12.5 s
D2
D1
M