Table of Contents
Advertisement
CDM-625 Advanced Satellite Modem
Front Panel Operation
5.4.8.3
CONFIG: CnC
CnC Frequency Offset:
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
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
PMSI mode: Idle
The Pre-Mapped Symbol Interface (PMSI) is a function associated with DoubleTalk
®
that permits the modulator in a selected unit to provide a direct copy of its output (the
in-Carrier
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
▲ ▼
Idle
Redundancy
Talk
Listen
Frequency Offset
PMSI
(Idle, Redundancy, Talk, Listen)
arrow keys to select the desired configuration, then press ENTER.
Select when CnC is not used.
Select when CnC is used in a 1:1 or 1:N redundancy configuration.
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).
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).
MN-0000036 (Ref MN/CDM625.IOM)
(range 1-032)
+/-015 kHz
arrow keys, then press ENTER.
▲ ▼
5–31
Revision 1
(34v)
(v)
®
Carrier-
Advertisement
Table of Contents
