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ROSS
During burst map reception the remote reads the ACK flag and either increments or resets
missed ACK counter. The missed counter is initialized and invoked when the first or next
message received has the flag set to zero '0'. It then starts a 10 missed count before incrementing
the power value by 3dB step. The second counter is received ACK's which has a flag set to
'1'and the count must receive 5 consecutive good ACK's before resetting missed ACK counter.
Once reset the power hunt stops and the value is retained and put into a variable called DPC
Delta.
There are three separate stored power components, Baseline Power, DPC Delta, and SOTM
Offset. Note SOTM Offset is a reserved variable for future use.
Baseline Power is either Home State default power value which is applied at initialization, CLI
force home state or VMS force reverts or the last value received from VMS. The baseline power
value is based on link budget calculations which may be subject to error in SOTM environments.
DPC Delta is a shared value between SPH and DPC. SPH applies its offsets during STDMA
mode only, while DPC adjustments are made in SCPC only due to environmental conditions,
unknown budget calculations (ocean coverage errors) and also traveling through power variances
within a satellite beam. These two power offsets share this variable with only one exception DPC
can overwrite the SPH value.
Operational Conditions
When enabling SPH it is only available in STDMA. Switching to SCPC disables this
function allowing DPC to modify independently. However, the SPH value remains stored in
DPC delta variable unless over written.
Once set the delta value remains effective throughout switching states, SCPC or STDMA
unless overwritten by DPC.
The current SPH gets stored in the DPC delta variable for use in SCPC mode and STDMA
during reverts (Home State). It is cleared during a force revert, either from VMS or CLI.
There are two counters, missed ACK and other is received ACK's.
SPH power is an incremental 3dB step value (added or subtracted) up to 9dB after 10 cycles
(burst maps) of missed ACK's.
The missed ACK counter is cleared after receipt of 5 consecutive received ACK's.
Boot & Initialization: (burst transmission succeed)
1. The default Home State power value is applied to the base modem modulator on boot-up.
2. After transmission grant, remote bursts to corresponding STDMA controller with ACK +
Registration request message.
3. If hub reception is NOT impaired and transmission acquisition is completed the burst
controller sets the missed ACK flag to '1' indicating to corresponding remote good burst.
4. No power adjustment is required. "SPH value remains at zero value"
5. VMS responds to registration request sending registration configuration to remote.
Comtech EF Data, Vipersat Products
MN/13070
Page 26 of 87
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