PEB24911HV13 Lantiq, PEB24911HV13 Datasheet - Page 99

• Manufacturer Part Number: PEB24911HV13
• Manufacturer: Lantiq

Specifications of PEB24911HV13

• Lead Free Status / Rohs Status: Supplier Unconfirmed

Loopbacks #1, #1A and #2 are controlled by the exchange. Loopbacks #1 is closed by
the DFE-Q V2.1 itself whereas loopbacks #1A and #2 are remote controlled and closed
in the repeater and NT. Loopback #3 is closed and controlled by the terminal.
All four loopback types are transparent. This means all bits that are looped back will also
be passed onwards in the normal manner. The propagation delay of B- and D-channel
data is identical in all loopbacks.
Beside the remote loopback stimulation via the EOC- and MON-channel the DFE-Q V2.1
features also direct loopback control via its register set. The next sections describe how
these loopbacks are closed and opened using C/I- and MON-commands.
4.4.1.1
Loopback #1 is closed by the DFE-Q V2.1 as near to the U-interface as possible. For this
reason it is called analog loopback. The 6 dB range attenuation in the receive path is
active.
Transparent
All analog signals will still be passed on to the U-interface. As a result the NT-station will
be activated as well. Only the internal loopback signal is processed. Signals on the
receive pins are ignored. For this reason the device stays in the “Line Active” state
(upstream ACT-bit cannot be received).
Loopback Activation
Before an analog loopback is closed the device should have been reset and put into
state “Deactivated” first before Loop-back #1 is closed. Then the C/I-command ARL
(activation request loopback) must be applied continuously as long as the loopback is
requested.
Loopback Deactivation
In order to open an analog loopback again the device should be reset by applying the C/
I-command RES (or by pin reset). This ensures that the echo coefficients and equalizer
coefficients will converge correctly when activating the next time.
The example below demonstrates the control of loopbacks #1.
•
<––––– C/I DC
Data Sheet
NT IOM
Analog Loopback (No.1)
®
-2
(1111B) C/I DI
LT IOM
C/I ARL
®
-2
(1111B) –––––>
(1010B) <––––– ; Close loopback #1
89
Operational Description
PEF 24911
2001-07-16