psf21911 ETC-unknow, psf21911 Datasheet - Page 72

• Manufacturer Part Number: psf21911
• Description: Isdn Echocancellation Circuit Terminal Applications Iec-q
• Manufacturer: ETC-unknow

PSB 21911
PSF 21911
U-Transceiver
Pending Deactivation of S/T
The U-transceiver has received the UOA-bit at zero after a complete activation of the S/
T-interface. The U-transceiver deactivates the S/T-interface by issuing DR in the C/I-
channel. The value of the ACT-bit depends on its value in the previous state.
Pending Deactivation of U-Interface
The U-transceiver waits for the receive signal level to be turned off (LSU) to enter the
“Receiver Reset” state and start the deactivation procedure.
Pending Receive Reset
The “Pending Receive Reset” state is entered upon detection of loss of framing on the
U-interface or expiry of timer T1. This failure condition is signalled to the LT-side by
turning off the transmit level (SN0). The U-transceiver then waits for a response (no
signal level LSU) from the LT-side to enter the “Receive Reset” state.
Pending Timing
The pending timing state assures that the C/I-channel code DC is issued four times
before the timing signals on the IOM-2 interface are turned off.
In case the NT-auto mode (Pin AUA=1) is selected the recognition of the LT wake-up
tone TL is assumed everytime the “Pending Timing” state has been entered from the
“Test” state. This function guarantees that the NT (in NT-auto mode) starts one single
activation attempt after having been resetted. After the assumed TL recognition in this
state the activation will proceed normally.
Receive Reset
The “Receive Reset” state is entered upon detection of a deactivation request from the
LT-side, after a failure condition on the U-interface (loss of signal level LSUE), or
following the “Pending Reset” state upon expiry of timer T1 or loss of framing. No signal
is transmitted on the U-interface, especially no wake-up signal TN, and the S-transceiver
or microcontroller is requested to start the deactivation procedure on the NT-side (DR).
Timer T7 assures that no activation procedure is started from the NT-side for a minimum
period of T7. This gives the LT a chance to activate the NT.
The state is left only after completion of the deactivation procedure on the NT-side
(receipt of the C/I-channel code DI), unless a wake-up tone is received from the LT-side.
Semiconductor Group
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