PEF2091 Siemens Semiconductor Group, PEF2091 Datasheet - Page 159

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

Reset for Loop
"Reset for Loop" resets the Receiver in order to guarantee a correct adaption of the
echo- and equalizer coefficients.
Receive Reset
The "Receive Reset" state assures that for a period of T7 no signal, especially no
wake-up signal TL, is sent on the U-interface, i.e. no activation procedure is started from
the LT side. A wake-up signal TN, however, from the NT side is acknowledged.
S/T Deactivated
The state "S/T Deactivated" will be entered if the received ACT- and SAI-bits are set to
(0). In this state the signal SL3T, ACT = (0), DEA = (1) and UOA = (0) are transmitted
downstream. The C/I-code UAI is issued upstream while the received SAI = (0).
In order to initiate a complete activation from the S/T deactivation state, the LT needs to
set the UOA-bit to (1). This will occur if either of the following three conditions are met:
– C/I = AR
– SAI = (1) & AR
– SAI = (1)
"S/T deactivated" will be left if the received ACT bit is (1), or the C/I code AR0 is applied.
Tear Down
In "Tear Down" state, transmission ceases in order to deactivate the basic access, and
the IEC-Q waits for a response (no signal level, LSU) from the NT side.
Tear Down Error
"Tear Down Error" state is entered after loss of framing has been detected. Transmission
ceases in order to deactivate the basic access and the IEC-Q waits for a response (no
signal level, LSU) from the NT side. EI3-indication is transmitted after a transition forced
by RES1 from the Wait-For-TN or EQ-Training states. In the case of transition from the
"Loss of Synchronization" state RSY is sent.
Semiconductor Group
(TE activation with exchange control [C/I UAR downstream])
(TE activation without exchange control [C/I DC downstream])
(LT activation)
159
Operational Description
Data Sheet 01.99
PEB 2091
PEF 2091