Technical Description
nxE1
Plug-in
Unit*
Plug-in
Unit
nxE1
7470
nxE1
Plug-in
Unit
Rx Loop
Connection Loop
AIS
AIS
AIS
Line Loop
Local Loop
TDM Bus
* Only MMU
Figure 82 Loops
The following loops on the near-end Radio Terminal are supported in order to
find out if the MMU or RAU is faulty.
IF Loop
In the MMU the traffic signal to be transmitted is, after being
modulated, mixed with the frequency of a local oscillator and
looped back for demodulation (on the receiving side).
RF Loop
In the RAU a fraction of the RF signal transmitted is shifted
in frequency and looped back to the receiving side.
9971
MMU MMURAURAU
Rx LoopIF Loop RF Loop
Near-end Far-end
Note: For MMU2 E/F, also a Local Loop
is available at the Far-end MMU.
Figure 83 Radio Terminal loops
The AAU supports a Loop Back function described in Section 3.8.2.2 on page
48.
108
12/221 02-CSH 109 32/1-V1 Uen A 2008-03-14
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