Comtech EF Data DT-4500 Series - A.2 Backup Converter (BU)

DT-4500 Series C- and Ku-Band Down Converters MN/DT4500.IOM
Appendix A Revision 2
A–2
A.2 Backup Converter (BU)
The "Daisy Chain" terminates in the BU. The BU has a microprocessor that
performs fault detection, self-reconfiguration, and the logical switching
functions. If the BU does not have a fault, it assumes the frequency and
attenuation of the faulted converter and compensates for the chain loss. The BU
accomplishes this via operation of the HSB and the online converter’s removable
switch module.
A.2.1 High Speed Bus (HSB)
In the "Daisy Chain" configuration, the BU communicates with the online units
through the High Speed Bus interface (HSB). This allows the BU to detect faults
and reconfigure itself to replace the faulted converter. The BU also uses the HSB
to monitor configuration changes made to an online converter. Changes in
frequency, gain, or polarity – as well as information from new online units – are
immediately entered into the backup table. The HSB does not interfere with the
remote serial communication link access to any of the converters in the chain.
A.2.2 Removable “Personality” Modules
See Chapter 2. SPECIFICATIONS or contact Comtech EF Data Product
support for the listing of modules available to both the DT-4500 Series
Down Converters and the UT-4500 Series Up Converters.
Depending on the application, the converter chassis rear panel module slot
accepts an Input/Output Module (IOM), Polarity Switch Module (PSM), Transmit
Switch Module (TSM), Equalizer Module (EQM), or Receive Switch Module (RSM).
The converter RF, IF, and High-Speed Bus (HSB) connectors are integral to the
installed module.
The converter employs an IOM for non-redundant (also called standalone or
single thread) operation. The IOM is also used for unit testing.
A.2.2.1 Converter Switching
In redundancy applications where converters are "Daisy Chained" to provide
distributed online protection switching to a BU, an RSM is used in place of an
IOM. The RSM contains IF switches for input/output looping of the signal.