Comtech EF Data CDM-740, Инструкция по установке и эксплуатации

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CDM-740 Advanced Satellite Modem Revision 0
Front Panel Operation MN-CDM740
5–9
5.4.2 CONFIG: Rx
Rx-IF Freq FEC Demod Data Descram Pilot
(Data 9980.000kbps, 2851.429ksym)
(
◄►
)
Select
IF
,
Freq
,
FEC
,
Demod
,
Data
,
Descram
, or
Pilot
using the
◄ ►
arrow keys, then press
ENTER
.
5.4.2.1 (CONFIG:) Rx Æ IF
Alpha Rolloff: .20 (.20,.25,.35)
Spectrum Invert:
(
◄►
E)
When in DVB-S2 mode only:
To set the expected filter Rx Alpha Rolloff
(
α
)
of the carrier, on
the top line select
.20
(20%),
.25
(25%), or
.35
(35%) using the
▲ ▼
arrow keys. The default
selection is
0.20
(20%).
The Rx Alpha Rolloff
(
α
)
dictates how fast the spectral edges of the carrier are attenuated beyond
the 3 dB bandwidth. With 20% rolloff the edge falls off more quickly than with 25% and 35%.
Note: This menu is not valid in DVB-S mode
, where the Rx Alpha Rolloff
(
α
)
is
fixed
at 35%.
To set Rx Spectrum Inversion, use the the
◄ ►
arrow keys to move to the
Spectrum Invert
operation on the bottom line, then set operation as
On
or
Off
using the
▲ ▼
arrow keys.
Once the Alpha Rolloff and Rx Spectrum Inversion settings are made, press
ENTER
.
5.4.2.2 (CONFIG:) Rx
Æ
Freq (Frequency)
Rx-IF Frequency: 0050.0000 MHz
(
◄►
E)
To edit the Rx-If Frequency, select each digit to be edited using the
◄ ►
arrow keys, then edit the
value of that digit using the
▲ ▼
arrow keys. Press
ENTER
when done.
The available frequency ranges are
0050.0000
to
0180.0000
(50-180) MHz, and
0950.0000
to
2150.0000
(950-2150) MHz (L-Band). The resolution is
100Hz
.
5.4.2.3 (CONFIG:) Rx
Æ
FEC
Rx FEC: LDPC+BCH
This is a ‘status only’ message. The CDM-740 features LDPC+BCH (Low-Density Parity Check
+ Bose, Chaudhuri, and Hocquengham) FEC as its sole available Rx FEC type.