PEF2091 Siemens Semiconductor Group, PEF2091 Datasheet - Page 153

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

TN
Note 42: Transition from state Deactivated to state Awake will only be done if the C/I
BBD0/1
Timers
The start of timers is indicated by TxS, the expiry by TxE. Table 29 below shows which
timers are used in LT modes:
Semiconductor Group
Tone (wake-up signal) received from the NT.
When in the "Deactivated" state, the IEC-Q is requested to start an
activation procedure and to inform the LT side making use of the
C/I-channel code AR. When in the "Wait for TN" state, the signal TN sent by
the NT acknowledges the receipt of a wake-up signal TL from the LT.
When an analog loop-back is operated, the wake-up signal TL sent by the
LT-transmitter is detected by the LT receiver.
The TN-criteria is fulfilled when 12 consecutive periods of the 10 kHz
wake-up tone were detected.
command DC is issued in downstream direction, as indicated in the state
diagram. However, the wake-up tone will still be detected and latched by the
IEC-Q even if the C/I command DC is not present. In this case the IEC-Q
will not react to the C/I commands AR, AR0, ARX and UAR. Furthermore, if
the DC command is issued later on, the IEC-Q will activate immediately. If
a previously received wake-up tones should be ignored, e.g. because it is
"old" and no more valid, the user might want to reset the wake-up tone
before further action. This can be done with any kind of reset (see "Reset
Behavior", page 94). The wake-up tone can also be reset by the C/I
command RES1, if it is applicable (state dependent).
Binary "0" or "1s" detected in the B- and D-channels
This internal signal indicates that for a period of time of 6–12 ms a
continuous stream of binary "0s" or "1s" has been detected. It is used as a
criterion that the Receiver has acquired frame synchronization and both its
EC- and EQ-coefficients have converged. BBD1 corresponds to the signals
SN2 or SN3 in the case of a normal activation and BBD0 corresponds to the
internally received signal SL2 in the case of an analog loop-back or possibly
a loop-back 2 in the NT.
153
Operational Description
Data Sheet 01.99
PEB 2091
PEF 2091