Scenario 1 - First Light Over Galway
Shift Turnover Notes
Section titled “Shift Turnover Notes”Date: Monday, 1348 Local (Galway runs UTC in March) Station: GW-01 Galway, Ireland — NATS Europe Operator on Duty: You Site Lead: Charlie Brooks (on-site, front office)
Good to have you across the water. Acceptance crew signed the hardware off last night and left it stowed: tracker pointing south, receiver on their test carrier. First MERIDIAN window opens at 14:03 and that is the site’s first light, so I would like the station ready before it, not during it. Sweep it, tune it, park it on the rise. I am in the front office if you need me. You will not.
— Charlie (text, 1347)
GW-01 finished construction acceptance last night. The RF chain is aligned and the reference is disciplined; what has never happened here is an end-to-end contact against a live spacecraft. Today’s shift is that test, and the station is not configured for it. You have fifteen minutes.
Current Operations
Section titled “Current Operations”| Satellite | Type | Owner/Ops | Status at Turnover |
|---|---|---|---|
| MERIDIAN-SAR-1 | LEO SAR imager (sun-sync) | MERIDIAN Constellation Operations (Rotterdam) | Healthy, imagery onboard awaiting downlink |
| MERIDIAN-SAR-2 | LEO SAR imager (sun-sync, offset plane) | MERIDIAN Constellation Operations (Rotterdam) | Healthy, second contact of the shift |
These are not TIDEMARK. A MERIDIAN pass runs horizon-to-horizon in under ten minutes above the mask, and the geometry changes continuously: range, azimuth rate, Doppler, all of it. The pedestal and the pass scheduler do the pointing math; your job is to have the station configured before AOS.
Pass Plan (from the scheduler, 5° mask, epoch 13:48:00 UTC)
Section titled “Pass Plan (from the scheduler, 5° mask, epoch 13:48:00 UTC)”| Contact | AOS | Rise azimuth | Max Elevation | LOS | Set azimuth |
|---|---|---|---|---|---|
| MERIDIAN-SAR-1 | 14:03:10 | 000° | 28° at 14:06:45, 761 km | 14:10:18 | 224° |
| MERIDIAN-SAR-2 | 14:18:42 | 130° | 25° at 14:22:10, 828 km | 14:25:40 | 000° |
The scheduler works the 5° elevation mask, not the geometric horizon. SAR-1 actually breaks the horizon at 14:02 from azimuth 005°; it clears the mask a minute later due north. Read AOS off the Pass Schedule tab.
Link Parameters
Section titled “Link Parameters”LNB is high-side injection: IF = LO − RF (13,100 MHz LO). Vermont was low-side. Same arithmetic, opposite sign, and the spectrum is inverted: a higher RF lands at a lower IF.
| Signal | RF (MHz) | IF (MHz) | Format |
|---|---|---|---|
| SAR-1 imagery downlink | 11,686 | 1,414 | QPSK 3/4, 36 MHz |
| SAR-1 telemetry beacon | 11,711 | 1,389 | CW |
| SAR-2 imagery downlink | 11,730 | 1,370 | QPSK 3/4, 36 MHz |
| SAR-2 telemetry beacon | 11,703 | 1,397 | CW |
Doppler
Section titled “Doppler”At 11.7 GHz the range rate on these passes is worth about ±270 kHz: +274 kHz as SAR-1 breaks the horizon, zero at culmination, −271 kHz at LOS. The 36 MHz imagery carrier shrugs it off. The CW beacon does not: on a 2 MHz span it walks visibly across the analyzer. Because the LO is high-side, the beacon appears below 1,389 MHz while the bird approaches and above it after culmination.
Acceptance
Section titled “Acceptance”| Check | Pass Criterion |
|---|---|
| Downlink C/N, high-elevation segment | ≥ 8 dB, held through the decode |
| C/N at culmination | ≥ 9 dB (predicted ~11 dB; flag to Rotterdam if more than 3 dB low) |
| Decode window | C/N crosses 8 dB near 18° elevation on the way up, peaks at culmination: roughly max-el ± 1.5 min. Do not chase a decode at the horizon. |
GW-01 Equipment Status (as the acceptance crew left it)
Section titled “GW-01 Equipment Status (as the acceptance crew left it)”| Equipment | Status | Notes |
|---|---|---|
| 4 m Ku tracker | Powered, manual, stowed az 180° / el 3° | Program-track available; ephemeris current. Needs parking on the rise azimuth. |
| LNB | 13,100 MHz LO, reference locked | Stable |
| GPSDO | Locked, 9 satellites | Disciplined. Confirm on GPS Timing before anything else keys off it. |
| RX modem 1 | 1,400 MHz / 20 MHz / BPSK 1/2 | The crew’s loopback test carrier. Retune for SAR-1 imagery. |
| Spectrum analyzer | 1,414 MHz centre, 60 MHz span | Move it to the beacon, 2 MHz span. |
| BUC / HPA | Muted / disabled | No uplink tasking this shift |
Contact Checklist
Section titled “Contact Checklist”Before AOS (13:48 – 14:03)
Section titled “Before AOS (13:48 – 14:03)”- Dashboard: only the RX AGC no-carrier warning (noise only, empty sky); no faults
- GPS Timing: GPSDO locked, not in holdover
- RX Analysis: LNB LO 13,100 MHz; work out the SAR-1 IF before you tune to it
- RX modem 1: 1,414 MHz / 36 MHz / QPSK / 3/4, applied
- Spectrum analyzer: centre 1,389 MHz (SAR-1 beacon), span 2 MHz
- Pass Schedule: SAR-1 AOS time and rise azimuth confirmed
- ACU: tracker parked az 000° / el 5°, then program-track, target MERIDIAN-SAR-1
SAR-1 Pass (14:03 – 14:10)
Section titled “SAR-1 Pass (14:03 – 14:10)”- Beacon visible on RX analysis (confirms you are on the bird)
- RX modem lock on the imagery carrier
- C/N ≥ 8 dB through the high-elevation segment, ≥ 9 dB at culmination
- Watch the beacon cross 1,389 MHz at culmination and know why it came from below
Between Contacts (14:10 – 14:18)
Section titled “Between Contacts (14:10 – 14:18)”- RX modem 1: 1,370 MHz
- Spectrum analyzer: centre 1,397 MHz (SAR-2 beacon), span 2 MHz
- ACU: retarget program-track to MERIDIAN-SAR-2 before it rises
SAR-2 Pass (14:18 – 14:25)
Section titled “SAR-2 Pass (14:18 – 14:25)”- 1,397 MHz beacon detected on RX analysis, RX modem locked, C/N ≥ 8 dB
After LOS
Section titled “After LOS”- Shift log: time, bird, result, peak C/N and the elevation it happened at
End of Briefing
Section titled “End of Briefing”Every ground station has exactly one first light. Rotterdam is watching for the acceptance numbers, Charlie is watching to see whether Vermont sent him an operator or a liability, and the pass starts whether you are ready or not.
Fifteen minutes. Sweep it, tune it, park it on the rise.
Good luck.