Preliminary Information
T1.601-1988 standards. The activation sequence for
the DSLIC is mode dependent and is outlined in
Figures 6a) and b).
In the LT mode, the request for activation can be
initiated in two ways. Setting the start/stop bit in the
Control Register 1 will result in the generation of a
repeated pattern of four +3 symbols followed by four
-3 symbols producing a 10 kHz activation tone (TL)
for 3 milliseconds. The DSLIC can also be activated
by receiving a 10 kHz activation tone from the NT
(TN).
Once the NT has generated a tone,
progression through the state machine follows the
algorithm as shown in Figure 6a.
In the NT mode, the request for activation can be
initiated in two ways. Setting the start/stop bit in the
Control Register 1 will result in the generation of a
repeated pattern of four +3 symbols followed by four
-3 symbols resulting in the transmission of the NT
activation tone (TN).
The DSLIC can also be
activated by receiving TL from the LT to which the
NT will respond with its own activation tone (TN).
Progression through the state machine will follow the
algorithm as shown in Figure 6b.
During the activation sequence, there is an extensive
exchange of signals between the LT and the NT.
MT8910-1
This handshaking of information is required to allow
individual transceivers to train both their echo
cancellers and decision feedback equalizers. All
possible signals are described below.
•
TN:
A 10 kHz activation tone sourced by the
NT which is generated by sending a
continuous pattern of four +3 symbols
followed by four -3 symbols.
SN0 is a no signal condition which is
used to indicate to the LT that the NT
has finished training its echo canceller.
An NT generated signal consisting of a
framed (but not superframed),
scrambled 2B1Q signal which carries all
1s in the B-, D- and M-channels. This
signal is used to train the NT’s echo
canceller.
An NT generated signal consisting of a
framed (but not superframed),
scrambled 2B1Q signal which carries all
1s in the B-, D- and M-channels. This
signal is used to train the LT’s DFE.
An NT generated signal consisting of a
fully framed and superframed scrambled
2B1Q signal which carries information in
all the B-, D- and M-channels.
•
SN0:
•
SN1:
•
SN2:
•
SN3:
MRST Pin
ST.Tx = Start Timer x
STP.Tx = Stop Timer x
LAR = Local Activation Request
LDR = Local Deactivation Request
SFS = Superframe Synchronization Acquired
Expiry of T2
RCV Reset
Tx-SL0
RCV TN
ST.T0
STP.T2
Expiry
of T0
Alerting
Tx-TL (3ms)
ST.T1
LAR
ST.T0
Expiry of
T1
RCV TN
STP.T1
Full Reset
Tx-SL0
RCV TN
ST.T0
Awake
Tx-SL0
End SN1
EC Training
Tx-SL1
EC
Converged
Framing
Tx-SL2
SFS
STP.T0
Active
Tx-SL3
Awaiting Reply
Tx-SL0
Expiry of T0
Expiry of T0
ST.T3
Expiry of T0
ST.T3
(Loss of
signal and
LDR),
ST.T2
STP.T3
(Loss of signal
and LDR) or
Expiry of T3
BFS Lost > 480ms
1
or LDR
ST.T3
Pending Deact.
Tx-SL0
T0 = 15 sec timer
T1 = 480 ms timer
T2 = 40 ms timer
T3 = 520 ms timer
Note
1
: Loss of received signal will result in loss of sync.
Figure 6a - Activation/Deactivation State Diagram - LT Mode
9-9
MITEL [ MITEL NETWORKS CORPORATION ]
