TSAT 3000 - Telemetry and data transfer via SATellite
TSAT 3000 Configuration Parameter Description, January 2013 Page 81 of 124
RESERVED 1 and 2:
Reserved for future usage. Should always be zero.
Using the “PPR Facility” will affect the size of Outbound and Inbound data packets:
Whenever slots are reserved to RTs (and RTs requested to retransmit), the number of bytes
available for Application or Management data in this
Outbound packet is decreased by 2 or 3
bytes:
• 2 bytes when collision is detected in position 0 … 7.
• 3 bytes when collision in detected in position 8 … 14.
Therefore, the minimum PKT_OUTBOUND_SIZE is now defined to be:
• 28 bytes when
PULSES = 0. (I.e: PPR is disabled)
• 30 bytes when
PULSES = 2 … 8.
• 31 bytes when
PULSES = 9 … 15.
The size of the Inbound packet (PKT_INBOUND_SIZE) is also decreased, to give room for the
specified number of pulses at the given separation. The time between Inbound packets is
given by
PHL_INBOUND_GUARDPERIOD. You can specify a given number of micro-seconds,
or select to use
DEFAULT value (i.e. –1). When DEFAULT is used, the Guard-Period is
calculated to be:
• PPR is disabled
: Guard-Period = 4 symbols.
Inbound-Size = Outbound-Size – 1.
• PPR is enabled
: Guard-Period = 4 + (PULSES – 1) x SEPARATION symbols.
Inbound-Size = Outbound-Size – RoundUP( ( (4 + (
PULSES – 1) x SEPARATION) x 2 x FEC) / 8).
Examples:
PULSES SEPARATION FEC Outbound-Size – Inbound-Size
0 0 ½ 1 byte
7 4 ½ 4 bytes
15 6 ½ 11 bytes
0 0 ¾ 1 byte
7 4 ¾ 6 bytes
15 6 ¾ 17 bytes
Note: DSP will be restarted 10 seconds after you’ve changed the CURRENT value of any
PPR-parameter that is affecting DSP configuration. That is
PULSES, SEPARATION,
RESERVED_1, TEST_2 and TEST_3. I.e. mask 0x0000.FFF0.
Ver >= 30.8.0: Restart of DSP is enabled by bit 2 (0x0004) in
UTL_UTILITY_MASK.
See also
POW_LISTEN_HPA_ON
POW_LISTEN_POLL
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