Note that all data volumes & rates are based on powers of 10, i.e. 1Gbit = 109 bits. HK and LL are included in normal mode.

TM Figures

Allocated TM14.5 kbits/s 
Download capacity per orbit (168 Days)26.309 GB= 210.470Gbits
SSMM allocation  

Operational Modes

Sources: SWA Budget Report Issue 1 (scaled to reach 14500 not 14848), SWA input to SAP Planning

ModeData Rate (bps)Duty Cycle (%)Duty Cycle (hrs / orbit)Orbital Volume (Gbits)
SWA Normal Mode1155199.6534018167.083
SWA Burst Mode (Scheduled)4133500.347 (min)1420.833
SWA Triggered Mode4475040.347 (max)1422.554

SWA's Book Keeping Algorithm trades off triggered burst modes against scheduled burst modes and it isn't entirely clear from available documentation what the native data rates of these burst modes are, only what proportion of the SWA TM budget is available after normal mode, LL and HK are accounted for. Discussions with C. Owen and ISWG imply that EAS can burst for 12 minutes per day total in scheduled burst mode, and that one triggered burst mode (dump of 5 minute rolling buffer) is equivalent to 7 minutes of scheduled burst mode. For simplicity's sake we assume the same is true for PAS (which has many different burst mode options in any case so this could probably reflect some form of reality). HIS does not respond to triggers.

For the purposes of calculating rates and duty cycles, then, we assume the following:

  1. Scheduled burst mode involves EAS, HIS and PAS.
  2. Scheduled burst mode replaces normal mode.
  3. EAS and PAS respond to triggers; HIS does not.
  4. Rate calculations are based on 5 minutes scheduled burst mode per day and 1 trigger response per day. A trigger produces 7/12 of the daily burst mode volume for EAS and PAS. Thus scheduled bursts produce 5/12 of the available daily burst mode volume for EAS and PAS and 100% of the available burst mode volume for HIS.

Objectives for SWA 



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