Comtech EF Data DT-4500 Series - Manual (Page 60)

DT4500 Series Down Converters MN/DT4500.IOM
Redundant System Operation Revision 1
42
A.2 B
ACKUP
C
ONVERTER
The "Daisy Chain" terminates in the backup Converter. The backup Converter has a
microprocessor, which performs fault detection, self-reconfiguration and the logical
switching functions. If the backup Converter does not have a fault, it will assume the
frequency and attenuation of the faulted converter and compensate for the chain losses.
This capability is accomplished through the operation of the High Speed Bus (HSB) and
the online converter detachable switch modules.
A.2.1 H
IGH
S
PEED
B
US
(HSB)
In the "Daisy Chain" configuration, the backup Converter communicates with the online
units through the high-speed interface bus (HSB). The backup Converter is able to detect
faults and reconfigure itself to replace the faulted converter. The HSB interface is also
used in the backup Converter to monitor configuration changes made to an online
converter. Changes in frequency, gain, or polarity are immediately entered into the
backup table as well as information from new online units. The high-speed bus does not
interfere with the remote serial communication link access to any of the converters in the
chain.
A.2.2 D
ETACHABLE
M
ODULES
Comtech EF Data's converters are designed with a detachable Input/Output Module
(IOM), which contain the signal path connectors. The IOM is utilized for single thread
operation, or for testing of the unit.
For redundant "Daisy Chain" operations, the on-line Down Converters are provided with
a detachable Receive Switch Module (RSM) replacing the IOM.
A.2.2.1 D
OWN
C
ONVERTER
S
WITCHING
The RSM contains IF switches for input/output looping of the signal. Options for the
RSM include SMA connectors for the RF Input signal, and 50 or 75
Ω BNC connectors
for the IF.