Comtech EF Data HPOD - Manual (Page 133)

HPOD C-, X-, Ku-Band High-Power Outdoor Amplifier MN/HPOD.IOM
Appendix B Revision 8
B–3
While the BU is constantly monitoring both units for their status, if either has a fault, use the last
(good) status as the configuration for the BU before the BU goes online. Once the BU goes
online, the redundancy auto/manual status reverts to manual mode, and the BU stays online
until reset by the user.
The user may reset the system by issuing a FBU=0 command to place the units back into auto
mode. When issuing this command, the BU then switches back to the “normal” configuration of
SSPAs 1 and 2 online. The system can be operated manually by sending an FBU=1 command
(which forces SSPA 1 to be backed up), or a FBU=2 command (which forces SSPA 2 to be backed
up) to the BU.
In 1:2 applications, the BU also stores an offset value, to be used when the BU replaces an active
unit, for each of the two online units. This offset may be set with the SBO= command. When an
online unit is being “backed up” the BU’s attenuator will be set to this value. This value may be
different than the attenuation value of the online unit to compensate for any gain mismatch
between the BU and online units.
To calibrate, do these steps:
Step Task
1 After proper operating levels have been established in online SSPA 1 and 2, store their attenuation settings
using the SBO= command in the backup unit.
For example – SSPA 1, the active SSPA, requires 15.00 dB of attenuation. SSPA 2, the BU unit, requires
10.00 dB: Enter the remote commands SBO=1,15.00 and SBO=2,10.00 to store these values.
2 Send the FBU=1 command to the BU unit. This will force the BU unit to replace SSPA 1. The BU unit will
read the setting stored by the SBO=1 command (in this example, 15.00) and apply this value to its own
attenuation setting. This value can now be tuned to compensate for any gain mismatch.
For example – If the output power is 1 dB too high in this state, send ATT=16.00 to the BU unit. If the Tx
level is now correct, send SBO=1,16.00 to the BU unit.
3 Repeat the above process to achieve desired level matching and for SSPA 2.