TSAT 3000 - 3.11.11 PHL_SLOT_PHASE_SETPOINT

TSAT 3000 - Telemetry and data transfer via SATellite
TSAT 3000 Configuration Parameter Description, January 2013 Page 82 of 124
3.11.11 PHL_SLOT_PHASE_SETPOINT
Default 0, Range –32768…+32767
The MIB parameter is expressed in micro-seconds (i.e. range is +/– 32 ms).
HUB: Not Used.
RT: The Slot Phase Setpoint is used to specify the point of time at which the DSP shall start the
transmission of a slot. It is required to set this variable on the RTs so that the HUB will receive
the packets from all RTs at exactly the same point of time, independent of the RT’s
geographical location (i.e. satellite delay). See also
PHL_SLOT_PHASE_DELAY.
Normally, it’s doesn’t care which value that is configured, because the Auto-Correction facility
will detect and correct any incorrect value.
The Slot Phase Setpoint Auto-Correction facility is implemented by the following procedure:
• The UW position (the point of time when the HUB receive the packet) of all Slot-Zero packets
(normally
POLL_ACK) is compared to PHL_TARGET_UW_POSITION, and the difference
reported back to the RT in the next
SYNC packet.
• The RT will use this information to correct its own Slot Phase Setpoint.
RT Ver <= 30.4.0 or
DSP <= 2.0.2: No adjustment will be done when the difference is less
than 1.5 symbols, as shown in table below (1 symbol = 15.625 us @ 64 kbps):
Delta UW Adjustment
Less than 1.5 symbols No adjustment
1.5 … 3.0 symbols
Adjust 1 symbol when this difference has been reported in 5
subsequent samples, or in 7 of the last 10 samples.
3.0 … 4.5 symbols Adjust 1 symbol, only
More than 4.5 symbols Adjust the reported difference
RT Ver >= 30.4.1 and DSP >= 2.1.0: No adjustment will be done when the difference is less
than 0.375 symbols, as shown in table below (1 symbol = 15.625 us @ 64 kbps). This
increased accuracy is required for proper PPR operation.
Delta UW Adjustment
Less than 0.375 symbols No adjustment
0.375 … 0.750 symbols
Adjust 1/4 symbol when this difference has been reported in
5 subsequent samples, or in 7 of the last 10 samples.
0.750 … 1.125 symbols Adjust 1/4 symbol, only
More than 1.125 symbols Adjust the reported difference
Setting bit 15 (0x8000 – UTILITY_STATIC_SLOTPHASE_SETPOINT) in UTL_UTILITY_MASK will
disable this facility.
See also
MAC_TIMESLOT_MARGIN.