Comtech EF Data CDM-625, Инструкция по установке и эксплуатации

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CDM-625 Advanced Satellite Modem Revision 1
Front Panel Operation MN-0000036 (Ref MN/CDM625.IOM)
In QDI (Quad D&I) mode, these data rates are
read-only
! The data rate will be the sum of the
tributary rates for all ports, and must be edited via the QDI menu.
The bottom line permits the user to select the Data Inversion feature (added for compatibility with
certain older equipment). Select
On
or
Off
using the
▲ ▼
arrow keys, then press
ENTER
.
5.4.4.6 CONFIG: Rx
Æ
Descram (Descrambler)
Rx Descrambler= Normal (Normal,Off)
Frame Descrambler (
v
)
Select
On
or
Off
using the
▲ ▼
arrow keys, then press
ENTER
.
The choice of descrambler is selected automatically, and depends on the exact operating mode:
•
If framing = None, the ITU V.35 descrambler (Intelsat variant) will be used.
•
If framing = IBS, the IESS-309 descrambler will be used, etc.
•
If LDPC decoding is configured, the standard ITU V.35 descrambler will be used.
•
If Turbo decoding is configured, a second descrambler selection is available - IESS-
315 V.35 instead of the TPC frame descrambler.
•
If TPC and Carrier-inCarrier™ are being used simultaneously the IESS-315 (V.35)
descrambler is the only permitted choice.
Rx Descrambler= IESS (Normal,IESS,Off)
IESS-315 V.35 Descrambler
5.4.4.7 CONFIG: Rx
Æ
Eq (Equalizer)
Rx Equalizer:
Disabled (Enable,Disable) (
v
)
Select
Enable
or
Disable
using the
▲ ▼
arrow keys, then press
ENTER
.
The integrated 5-tap adaptive equalizer can compensate for:
•
amplitude slope and variation over the symbol bandwidth
•
non-linear group delay variation over the symbol bandwidth.
It is particularly useful at higher symbol rates (up to 12.5 Msymbols/second) in situations where
long cable runs between equipment (downconverter and modem, for example).
The Eb/No estimate is performed after the adaptive equalizer block, which provides an easy way
to determine if the equalizer is providing any benefit. If the equalizer is first turned off, the Eb/No
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