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)
5.4.8.3 CONFIG: CnC
Æ
Frequency Offset
CnC Frequency Offset: (range 1-032)
+/-015 kHz (
34v
)
This screen permits the user to enter the maximum expected frequency offset between the outbound
interferer, and the desired inbound. It will normally correspond to the acquisition range of the
demod. Edit the CnC Frequency Offset value using the
▲ ▼
arrow keys, then press
ENTER
.
The upper limit of Frequency Offset is determined by the Rx symbol rate:
•
Below 32 ksymbols/sec: ±1 to ± (Rs) kHz, where Rs = symbol rate in ksymbols/sec
•
Between 32 and 389 ksymbols/sec: ± 1 up to a maximum of ± 32kHz
•
Above 389 ksymbols/sec: ±1 to ± (0.1Rs) kHz, up to a maximum of ± 200 kHz
This range is precalculated and displayed in the parentheses to assist the user.
5.4.8.4 CONFIG: CnC
Æ
PMSI
PMSI mode: Idle
(Idle, Redundancy, Talk, Listen) (
v
)
The
Pre-Mapped Symbol Interface (PMSI)
is a function associated with DoubleTalk
®
Carrier-
in-Carrier
®
that permits the modulator in a selected unit to provide a direct copy of its output (the
outbound interferer) to one, or many other modems. The other modem(s) may then choose to take
the PMSI signal and use it for its own CnC reference. This has applications in both 1:1 and 1:N
systems, and in certain other configurations. The Pre-Mapped Symbol Interface is an RS-485
multidrop bus system, where one device transmits and all other devices on the multi-drop bus are
configured to receive. In order to use this mode of operation, the appropriate cable (Comtech EF
Data part number CA-0000102) needs to be connected to the PMSI connector on the rear panel of
each modem. Consult Comtech EF Data Customer Service for details about this cable.
Use the
▲ ▼
arrow keys to select the desired configuration, then press
ENTER.
Idle
Select when CnC is not used.
Redundancy
Select when CnC is used in a 1:1 or 1:N redundancy configuration.
Talk
Select when CnC is used in other configurations, or for manual testing (the modem will
transmit a copy of its baseband modulated signal on the PMSI port).
Listen
Select when CnC is used in other configurations, or for manual testing (the modem will
receive the PMSI signal, and lock its modulator to this, permitting the CnC module to
use the other modem’s reference outbound interferer).
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