Scenario 6 - Old Faithful
Duration: 25-30 minutes Difficulty: Beginner Mission Type: Satellite Link Establishment
Shift Turnover Notes
Section titled “Shift Turnover Notes”Date: Thursday, 1400 Local Station: Vermont (VT-01) Operator on Duty: You Supervisor: Charlie Brooks (present)
Maine has been carrying AURORA-7 traffic for the past month while we finished the antenna upgrades. Now that VT-01 is back online, we’re taking the service back.
AURORA-7 is a legacy bird - stopped north-south station-keeping years ago to conserve fuel. The orbit’s inclined now. Maine had some signal dropouts when they first took over because they tried running program-track. Don’t make the same mistake.
I’ve already configured the beacon receiver and verified the encryption keys. You handle the rest - antenna, RF chain, modems. Show me you understand why this satellite needs different handling.
— Charlie
Active Services
Section titled “Active Services”| Satellite | Customer | Service Type | Status |
|---|---|---|---|
| AURORA-7 | Pacific Rim Communications | Maritime VSAT | Transferring from ME-02 |
Pacific Rim Communications provides connectivity for fishing fleets in the North Pacific. Their vessels rely on AURORA-7 for weather data, catch reporting, and crew welfare communications. Maine has been covering the service - now it’s Vermont’s responsibility.
AURORA-7 Operations Reference
Section titled “AURORA-7 Operations Reference”AURORA-7 is a legacy C-band satellite that’s been in service for over 15 years. To conserve fuel, the operators stopped north-south station-keeping years ago, which means its orbit is now inclined. From our perspective, it traces a figure-8 pattern in the sky over each 24-hour period.
Orbital Characteristics
Section titled “Orbital Characteristics”| Parameter | Value | Notes |
|---|---|---|
| Orbital Inclination | ~5° | Accumulated since station-keeping stopped |
| Daily Motion | Figure-8 pattern | North-south excursion over 24 hours |
| Program-Track Accuracy | Insufficient | TLE assumes geostationary position |
Tracking Mode Selection
Section titled “Tracking Mode Selection”| Satellite Type | Recommended Mode | Reason |
|---|---|---|
| Geostationary (active S/K) | Program-track | Satellite stays at fixed position |
| Inclined orbit | Step-track | Follows actual satellite position via beacon |
AURORA-7 Link Parameters
Section titled “AURORA-7 Link Parameters”Frequency Allocation
Section titled “Frequency Allocation”| Parameter | RF (MHz) | LO (MHz) | IF (MHz) |
|---|---|---|---|
| Beacon (Downlink) | 4,165 | 5,250 (LNB) | 1,085 |
| Carrier (Downlink) | 3,828 | 5,250 (LNB) | 1,422 |
| Carrier (Uplink) | 6,053 | 7,500 (BUC) | 1,447 |
IF Calculation Reference
Section titled “IF Calculation Reference”Downlink (LNB LO above RF):
IF = LO - RFUplink (BUC LO above RF, lower sideband):
RF = LO - IF, so IF = LO - RFModem Configuration
Section titled “Modem Configuration”| Direction | IF (MHz) | Bandwidth | Modulation | FEC |
|---|---|---|---|---|
| Receive | 1,422 | 24 MHz | QPSK | 3/4 |
| Transmit | 1,447 | 24 MHz | QPSK | 3/4 |
Station Reference
Section titled “Station Reference”Vermont (VT-01) - Current State
Section titled “Vermont (VT-01) - Current State”| Equipment | Status | Notes |
|---|---|---|
| GPSDO | Locked | Timing reference stable |
| Antenna | Program-track on TIDEMARK-1 | Change target and mode |
| LNB | 5,250 MHz LO, powered | No change needed |
| BUC | 7,500 MHz LO, muted | Unmute after TX config |
| HPA | Disabled | Enable for transmission |
| Beacon Receiver | 1,085 MHz IF | Pre-configured by Charlie |
| RX Modem | 1,200 MHz, 36 MHz, BPSK 1/2 (parked from a test carrier) | Configure to 1,422 MHz, 24 MHz, QPSK 3/4 |
| TX Modem | 1,050 MHz (incorrect) | Configure to 1,447 MHz |
| Encryption | AES-256-GCM | Keys verified by Charlie |
Security Configuration
Section titled “Security Configuration”Charlie has verified the encryption configuration for AURORA-7. Check it yourself in the TX ENCRYPTION section of the TX Payload Data card on the TX Chain tab:
| Parameter | Value |
|---|---|
| Algorithm | AES-256-GCM |
| Key Status | Valid |
| Mode | Authenticated encryption |
Link Establishment Checklist
Section titled “Link Establishment Checklist”Antenna Acquisition
Section titled “Antenna Acquisition”- Current target: Verify antenna is on TIDEMARK-1
- Change target: Select AURORA-7
- Tracking mode: Program-track (for initial acquisition)
- Antenna position: Wait for slew to complete
- Beacon signal: Visible on spectrum analyzer at 1,085 MHz IF once the dish is on AURORA-7 (about -74 dBm under program-track; nothing there while the dish is still on TIDEMARK-1, 35° away). Step-track adds about 2 dB. Later, when your own carrier comes back down, the AGC turns its gain down by about 7 dB and the beacon reads that much lower on the analyzer: the AGC holding its output level, not the pointing (the ACU beacon C/N does not move)
Step-Track Transition
Section titled “Step-Track Transition”- Tracking mode: Switch to step-track
- Beacon lock: Acquired (ACU Control shows “Beacon Lock: LOCKED”)
- Signal quality: Stable (step-track optimizing)
Receive Chain
Section titled “Receive Chain”- Spectrum analyzer: Reconfigure for 1,422 MHz IF, 50 MHz span, Max -30 dBm, Min -90 dBm, RBW Auto (it was set by hand to 300 Hz for the beacon)
- RX modem frequency: 1,422 MHz
- RX modem bandwidth: 24 MHz
- RX modem modulation: QPSK, FEC 3/4
Transmit Chain
Section titled “Transmit Chain”- TX modem frequency: 1,447 MHz (calculated from LO - RF)
- TX modem bandwidth: 24 MHz
- TX modem modulation: QPSK, FEC 3/4
- Encryption: Verified active
- BUC: Unmuted
- HPA: Enabled
Full Duplex Verification
Section titled “Full Duplex Verification”- RX modem: Locked on our own carrier, C/N ≥ 8 dB (expect about 14 dB, give or take a dB or two as step-track works the inclined orbit)
- TX path: Active, no warning or critical alarms
- Dashboard: All indicators green
Quick Reference
Section titled “Quick Reference”Why Step-Track?
Section titled “Why Step-Track?”| Program-Track | Step-Track |
|---|---|
| Uses TLE orbital predictions | Uses beacon signal strength |
| Assumes satellite at fixed position | Follows actual satellite position |
| No signal feedback | Continuously optimizes pointing |
| Works for geostationary satellites | Required for inclined orbits |
Acquisition Sequence
Section titled “Acquisition Sequence”- Program-track points antenna to approximate position
- Beacon becomes visible on spectrum analyzer
- Switch to step-track mode
- ACU optimizes pointing using beacon signal
- Configure the receive chain, then bring up the transmit chain
- Confirm the receiver locks on our own carrier coming back down
End of Briefing
Section titled “End of Briefing”Maine is standing by to hand over AURORA-7 traffic once you’ve established the link. Pacific Rim’s fishing fleet doesn’t know or care about our internal station transfers - they just need connectivity.
Charlie configured the beacon and encryption. The rest is on you: acquire the satellite, enable step-track, configure the modems, and bring up the full duplex link.
This is your first inclined-orbit satellite. Understand why step-track matters - you’ll work with more aging birds as they reach end-of-life and stop station-keeping.
Get the link up, and Maine can release the service to Vermont.