Operation With Sdm-300L3 And Sms-301 - Comtech EF Data CRS-170A Installation And Operation Manual

CRS-170A L-Band 1:1 Redundancy Switch
Introduction
position and push the Switch Condition switches to the OFF position. See Section 3.7 Switch DIP
Settings for detailed information.

1.2.4 Operation with SDM-300L3 and SMS-301

The SMS‐301 is modified from the standard version that operates with 70/140 MHz IF
SDM‐300A modems. The BNC IF connectors are removed since the connectors and internal
switching are not suitable for L‐Band operation. Signals on the Status/Faults connector (J14) are
modified to provide +12VDC power output and A/B switch control outputs to the CRS‐170A. The
SMS‐301 has its own redundant power supplies, so the CRS‐170A receives redundant power.
Operation here is similar to operation with two CDM‐600L (CLM‐9600L) modems and a CRS‐150
switch. The SMS‐301 operates as the principal switch and controller, with the CRS‐170A
providing the required switching for L‐Band signals, references, and power supplies that the
SMS‐301 cannot handle. The SMS‐301 connects to two modems (an online unit and a standby
unit), monitors the fault status of these two units, and controls the routing of data to and from
the two units. IF signals, 10MHz reference signals, DC power for the BUC and LNB, and FSK
signaling to the BUC are switched in the CRS‐170A under control of the SMS‐301. In the case of
an equipment failure, automatic switching takes place to protect the traffic circuit. Consult the
Comtech EF Data SMS‐301 Redundancy Switch Installation and Operation Manual for detailed
information on operation of the SMS‐301. All operation as a 70/140 MHz modem switch applies
except that the RF switching is done in the CRS‐170A.
DIP switches on the CRS‐170A's front panel are set to establish modem‐specific operation. With
the SDM‐300L, place the Mode switch in the SDM‐300L/CDM‐600L (CLM‐9600L) position and
push the Switch Condition switches to the OFF position. See Section 3.7 Switch DIP Settings for
detailed information.
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