PEF2091 Siemens Semiconductor Group, PEF2091 Datasheet - Page 126

• Manufacturer Part Number: PEF2091
• Description: ICs for Communications(ISDN Echocancellation Circuit)
• Manufacturer: Siemens Semiconductor Group

Semiconductor Group
4.3.1
Figure 53 depicts the procedure if the activation has been initiated by the exchange side.
If activation is initiated with the C/I code AR, as shown in Figure 53, activation will fail if
the signal SN3 hasn’t been correctly received within 15 seconds. In this case the LT side
will indicate the C/I code EI3 instead of UAI and the device should be reset (see "LT
Modes State Diagram", page 147). In normal LT-NT configurations these 15 seconds are
much longer than average activation time which lies between 1-7 seconds, depending
on line characteristics, i.e. if this timer expires it is a strong indication for an error
condition.
In some configurations, however, e.g. a line with several repeaters, this timer could
expire under normal activation condition. For such configurations the IEC-Q provides the
C/I command ARX which can be used instead of the command AR for activation. If
activated with the ARX command the IEC-Q will continue the activation procedure, even
if the 15 seconds timer has expired.
Figure 53
INFO
INFO
INFO 2
INFO 3
INFO
Complete Activation Initiated by LT
S/T
Complete Activation Initiated by LT
0
0
4
SBCX
IOM -2
NT
DC
DC
PU
AR
AR
DI
AI
AI
R
IEC-Q
SL3T
SL3T
SL2
SN3
SN3
SN3 act = 0 sai 1
act
U-Reference Point
act = 0 dea = 1 uoa = 1
act
126
0 =
act
1 =
act
SN3T
SL3T
SN0
SN0
SN2
SL0
SN1
SL1
TN
TL
0 =
dea
1 =
dea
1 =
(sai
1 =
sai
=
=
=
uoa
uoa
1
0)
1 =
1 =
IEC-Q
Operational Description
IOM -2
ARM
UAI
LT
DC
AR
AR
DI
AI
R
Data Sheet 01.99
EPIC
ITD04241
PEB 2091
PEF 2091
R