Communication / Ground Link
Command / Telemetry Flow
Distinguish uplink commands, downlink telemetry, payload data, packet loss / retry, and prioritization with a teaching-grade flow model.
- Time estimate
- 20–30 min
- Complexity
- developing
- Maturity
- pilot ready
- Simulator readiness
- implemented
- Software available now
- Implemented — interactive command/telemetry priority and retry teaching lab at `/twin/learn/activities/comm_command_telemetry_flow`. Not a real radio, not a real satellite command interface, not licensed operations.
Student path
- Pick a command type, telemetry priority, packet-loss profile, and payload data queue.
- Set a pass window — read the timeline and what gets sent first.
- Identify what is deferred or dropped under prioritisation.
- Defend a priority order in your evidence reflection.
Learning outcomes
Student can explain what gets sent first when contact time is short and what happens to lost packets in a teaching priority queue (no real radio).
- Distinguish uplink commands from downlink telemetry and payload data.
- Explain how packet loss and retry affect what is delivered in a short pass.
- Defend a priority order for one mission scenario.
Concept primer
Distinguish uplink commands, downlink telemetry, payload data, packet loss / retry, and prioritization with a teaching-grade flow model.
Open the Command / Telemetry Flow lab at `/twin/learn/activities/comm_command_telemetry_flow` — browser-local teaching model (not a real radio, not a real satellite command path).
Order four items (critical command ack, housekeeping telemetry, payload science, lossy science chunk) by priority for a 5-minute pass; justify the ordering.
Interactive lab
Teaching-grade software activity slot — not a flight simulator or certified propagator.
Interactive lab
Command / telemetry flow (teaching)
Compose a short pass: pick a command type, telemetry priority, packet-loss / retry profile, and a payload data queue. The teaching model orders the queue by priority and shows what gets sent first — and what is deferred. Not a real radio, not a real satellite command path.
Pass timeline (teaching seconds)
Pass-window utilization: 70% (300s total)
Priority queue result
What gets sent first: Uplink first: Critical command ack (Schedule update (small, important)), then downlink Housekeeping telemetry (Housekeeping (high priority)).
Delivered (10)
- Critical command ack (Schedule update (small, important)) — uplink, 10s, retries 2
- Housekeeping telemetry (Housekeeping (high priority)) — downlink, 15s, retries 2
- Payload data chunk 1/8 — downlink, 23s, retries 2
- Payload data chunk 2/8 — downlink, 23s, retries 2
- Payload data chunk 3/8 — downlink, 23s, retries 2
- Payload data chunk 4/8 — downlink, 23s, retries 2
- Payload data chunk 5/8 — downlink, 23s, retries 2
- Payload data chunk 6/8 — downlink, 23s, retries 2
- Payload data chunk 7/8 — downlink, 23s, retries 2
- Payload data chunk 8/8 — downlink, 23s, retries 2
Everything queued fits in the pass window. Consider a longer payload queue or shorter pass to feel the prioritisation pressure.
Local self-check
Assessment (practice only)
Use this as a self-check and discussion starter. It is local-only and not a grade.
Optional: attaches a local summary (completed / quick checks / checklist count).
Quick check
Multiple choice self-check
This is a local self-check to support discussion. It is not a grade.
Quick check: In a typical CubeSat operations day…
Quick check: When packet loss is non-zero and contact is short, operators usually…
Discussion prompt
Short answer (local only)
Write notes for yourself or your group. Nothing is submitted.
Short answer: Defend a priority order for one 5-minute pass: critical command ack, housekeeping telemetry, payload science, and a non-critical chunk.
Checklist
Local checklist self-check
Use this to verify you covered key ideas. Nothing is submitted.
Checklist: Command/telemetry flow readiness (self-check)
0 / 4 checked
Local summary
Assessment summary (practice only)
Completion
0 / 4 sections complete
Quick checks
0 / 2 correct
Shown only to support self-check.
Checklist
0 / 4 items checked
Reminder
Local-only practice summary. Not a grade and not submitted anywhere.
What this preview is / is not
Assessment engine v0 boundary note
- Student view (local practice): use this as a self-check and discussion starter.
- Local-only preview/practice: your answers are not submitted.
- No backend, no accounts, no roster, and no LMS integration.
- Not a grade. No credential or official scoring is implied.
- Teacher visibility into student answers is not implemented in MVPF8.
- Evidence runtime engine arrives in Phase 9 (not in this preview).
Capture
Evidence capture (local-only)
Capture what you did, what changed, what you observed, and how you explain it. This stays in your browser unless you copy/share it manually.
Selected inputs
- Uplink command type: Schedule update (small, important)
- Telemetry priority: Housekeeping (high priority)
- Packet loss / retry profile: Occasional drops (~5 %)
- Payload data queue: Medium payload queue
- Pass window: 5 min
Generated outputs
- Pass window seconds: 300
- Delivered count: 10
- Deferred count: 0
- What gets sent first: Uplink first: Critical command ack (Schedule update (small, important)), then downlink Housekeeping telemetry (Housekeeping (high priority)).
- Reflection note: Everything queued fits in the pass window. Consider a longer payload queue or shorter pass to feel the prioritisation pressure.
Checklist
Evidence checklist
0/4 checked
Evidence artifact (local-only)
Command / Telemetry Flow
Captured: 2026-05-16T07:38:33.137Z · Level: high_school · Track: communication_ground_link
Summary
Copyable class summary
Copy a readable summary for class notes, or copy JSON for a structured record. Local-only: nothing is submitted.
Evidence artifact (v1) Activity: Command / Telemetry Flow Track: communication_ground_link Learner level: high_school Captured: 2026-05-16T07:38:33.137Z Mission brief: Teaching command/telemetry flow with priority queue, packet loss, and retries (no real radio, no real satellite command). Selected inputs: - Uplink command type: Schedule update (small, important) - Telemetry priority: Housekeeping (high priority) - Packet loss / retry profile: Occasional drops (~5 %) - Payload data queue: Medium payload queue - Pass window: 5 min Generated outputs: - Pass window seconds: 300 - Delivered count: 10 - Deferred count: 0 - What gets sent first: Uplink first: Critical command ack (Schedule update (small, important)), then downlink Housekeeping telemetry (Housekeeping (high priority)). - Reflection note: Everything queued fits in the pass window. Consider a longer payload queue or shorter pass to feel the prioritisation pressure. Checklist: - [ ] Distinguished uplink commands from downlink telemetry and payload data - [ ] Observed how packet loss + retries affect what arrives - [ ] Justified a priority order for a short pass - [ ] Treated this as a teaching flow — no real radio, no real satellite command Observations: (not provided) Reflection: Why this priority order is correct for short, lossy passes. Model boundary note: Local-only teaching model — not a certified RF link budget, not ITU/regulatory analysis, not licensed radio operations, not real satellite command, no SDR or remote hardware. Evidence is not submitted anywhere and is not a grade. Policy reminder: - Local-only capture. Not submitted anywhere. Not a grade.
Evidence capture
Expected outputs learners should be able to show after the lab (Phase 9 evidence engine preview available).
- Selected command type, telemetry priority, packet loss / retry, and payload queue
- Command-response timeline and ordered priority queue result
- What gets sent first and what is dropped or deferred
- Local self-check summary and copied evidence text
Reflection
Choose a command type, telemetry priority, packet loss / retry condition, and a payload data queue; read a command-response timeline and what gets sent first.
Responses are not persisted in this preview unless a specific activity component adds storage later.
Assessment / quick check
When contact time is short and packet loss is non-zero, why must operators set priorities for what gets sent first?
Teacher notes
Stress that uplink and downlink are different — small command bytes go up; big science data goes down — and short passes force prioritization.
Teacher use
Highlight that uplink and downlink are different: small commands go up, larger telemetry and science data come down. Short, lossy passes force prioritisation. This is a teaching flow only — no real radio, no real satellite command, no SDR.
Next activity
Suggested progression from the mission learning path. Links avoid missing activity routes.
Track 4 mini-course ends here — continue into the ADCS / Attitude Control mini-course (Track 5).