Downlink CONOPS - Case Bank
CFDP-based X-band downlink scenarios for the SAT / MCS / PLDP architecture, worked through one at a time.
Architecture at a glance
- SAT - our satellite, in low Earth orbit. It can only send data down via X-band (one-way), but can both send and receive over S-band (used for telemetry/commanding, "TM/TC").
- PLDP - our ground system that receives the raw signal from the Ground Station and turns it into usable images. It doesn't process data live during a pass - only afterward.
- MCS - the ground system that owns the S-band link (the only way to talk back up to the satellite). We're assuming a fast (10 Gbps) link between MCS and PLDP.
- CFDP, in "reliable" mode (Class 2) - the file-transfer protocol we're using to get images down. Confirmed decision: we want the standard's built-in ability to detect and resend missing data, rather than building our own custom fix for that.
Full details: fact.txt. Every open question tracked in question_bank.txt.
Cases
| Case | Scenario | Status |
|---|---|---|
| A | Simple, uninterrupted downlink - 4 images, 1 pass, baseline | constructed |
| B | NAK-driven repair cascading into the forward pass schedule | constructed |
| C | One large image, multi-pass delivery | WIP |
| D | Emergency interrupts a planned downlink | WIP |