Comtech EF Data CRS-150 Modem Redundancy Switch
- Supports a variety of modems
- Fully protects traffic paths
- User defined switchover conditions
- Extensive flexibility
CRS Series 1:1 Modem Reduncancy Switches
The Comtech EF Data 1:1 Modem Redundancy Switches are companion products for the following modems:
Their purpose is to continuously monitor a pair of modems in a redundant configuration, so that the unit automatically switches data and IF signals from the failed unit to the standby unit if an equipment failure or undesired traffic condition occurs.
This fully protects traffic paths, and the operator can have increased confidence that equipment failures will not adversely affect system availability.
There are two types of switches. The first type routes data and IF signals at the switch. The CRS-100 and CRS-150 are representative of this type of switching. These switches have individual connectors mirroring the data and IF interfaces available on the modems they support. Operationally, a copy of the Tx and Rx traffic is delivered to the offline modem so that both units see identical traffic signals.
The second type performs IF switching in a switch module and carries out data switching within modems interconnected by a Y-cable. The net result is the same: both modems see the identical Tx and Rx traffic signals permitting the continual comparison of fault status. This approach is used in subsytems with the CRS-170A and CRS-180.
A significant feature of the switches is the Auxiliary Serial connections between the two modems in the pair. The online unit interrogates the standby unit at regular intervals to determine its configuration. If a difference in configuration is detected, the online unit automatically reconfigures the standby unit, so that the configurations are always synchronized. The advantage of this feature is clear: If the standby unit is replaced, it does not have to be reprogrammed to match the online unit - the process is entirely automatic.
Manual and Automatic Switchover
Manual switchover is enabled from the front panel or remote control of the online modem.
Automatic switchover conditions are user-defined by setting two switches at the front of the unit. The user can select Unit Faults only, Unit Faults or Receive Traffic Faults, Unit Faults or Transmit Traffic Faults, or all three. This user-configured feature provides a great deal of flexibility in the operation of the switches.
Only one modem in the pair (the online unit) is permitted to transmit its IF carrier signal at any one instant. For total security, the offline modem mutes its TX carrier, and the switch provides further isolation by using an RF relay within the unit. Unlike some other 1:1 redundancy systems, which use a passive power combiner for this function (losing approximately 3.5 dB in output power level), the switch does not introduce any attenuation of output signal level.
The supplied G.703 interfaces support the T1, E1, T2, and E2 standards, in both balanced and unbalanced configurations. Support is also provided for 'G.703-like' signals at 512 and 1024 kbps.
Operators do not have to configure the interface type - control signals from the modems perform the selection automatically.
|Comtech CRS-150 General Specifications|
|Equipment Type||1:1 Redundancy Switch|
|Modems Supported||Comtech EF Data CDM-600 Digital Satellite Modem|
|Operating Modes||Fully Automatic|
Manual (via the front panel of the Online Modem, or via the Modem?s remote control interface)
|Architecture||Full bridging architecture, with configuration synchronization|
Tx Clock and Data signals fed to both Online and Standby units
Rx IF signal fed to both Online and Standby units Continuous fault comparison of Online and Standby units
(The configuration of Online and Standby units is synchronized via the Auxiliary Serial link between the two Modems)
|Switch Conditions||Switchover initiated following:|
Unit faults only, or:
Unit faults or Receive Traffic Faults, or:
Unit faults or Transmit Traffic Faults, or:
Unit faults or Receive or Transmit Traffic Faults
|Fault Detection Time||1 second maximum|
|Switchover Time||Within 0.5 seconds of fault detection|
|Main Data Interfaces||RS422/EIA530 DCE (25 pin D-type female, pinout per EIA530) to 10 Mbps|
V.35 DCE to 10 Mbps
Synchronous RS232 to 300 kbps
Serial LVDS to 20 Mbps
(A standard HSSI interface is provided with the addition of the Comtech EF Data CIC-20 LVDS/HSSI Interface Converter module, for operation up to 20 Mbps)
|G.703 Interfaces||G.703, T1, E1, T2 and E2, balanced and unbalanced (BNC connectors for 75 ohms unbalanced, and 15 pin D-type for 120 ohms balanced) Note that for T1 and E1 Drop and Insert applications the unit supports Rx, Tx connections, as well as Drop Data Out (DDO) and Insert Data in (IDI)|
'G.703-like'signals at 512 kbps and 1025 kbps
(through DDO and IDI ports)
|Overhead Interface||Intelsat IESS-308/309/310 Open Network overhead signals, including:|
IDR Overhead Data Channels (64 kHz, 8kHz, and Octet clocks)
IBS ESC and High-Rate ESC
Balanced External Reference Input
IDR Backward Alarm Inputs
(25 pin D-type male)
|Audio||2 x 4-wire 600 ohms audio interface, per Intelsat IESS-308 (9 pin D-type female)|
|IDR Backward Alarms||Backward Alarm Outputs BA-1 through BA-4 (Form C relays) per Intelsat IESS-308 (15 pin D-type female)|
|External Reference||75 ohms BNC, unbalanced input|
120 ohms balanced input
|IF Switching/Splitting||Transmit IF: Switched by RF relay (0.3 dB max loss)|
Receive IF: Passive power splitting (3.5 dB max loss)
|IF Impedance||Optimized for 50 ohms(> 20 dB return loss on external IF ports)|
75 ohms supported with the use of external RF transformers (supplied)
|IF Connectors||BNC female|
|IF Frequency Range||52 - 176 MHz|
|Weight||4.6 lbs (2.1 kg)|
|Dimensions||1.75 inches (44.5 mm) high, 19 inches (482.5 mm) wide,|
4.2 inches (107 mm) deep (excluding connectors)
|Power Requirements||4.5 Watts maximum|
+ 12 volts DC @ 250 mA (max)
-12 volts DC @ 120 mA (max)
Power is supplied by the Online and Standby Modems, and the unit current shares when both an >A= and >B= unit are present. These power supplies are electronically fused and protected.
A pair of auxiliary DC inputs are provided for powering external equipment connected to the main data interface, such as a CIC-20 Interface Converter
|Approvals||'CE' as follows:|
EN 55022 Class B (Emissions)
EN 50082-1 (Immunity)
EN 60950 (Safety)
FCC Part 15 Class B