Scenario 8 - Night Shift

Duration: 30-40 minutes

Difficulty: Intermediate

Mission Type: Solo Night Operations

Time Limit: 40 minutes

Shift Turnover Notes

Date: Saturday, 0215 Local

Station: Vermont (VT-01)

Operator on Duty: You

On-Call Supervisor: Dana Torres (sleeping - emergency escalation only)

Relieved By: Day shift at 0700

Turnover from Evening Shift

Evening shift operator logged the following at 2300:

All systems nominal. AURORA-7 link stable at handoff. Weather radar shows a front moving in from the northwest - expected arrival 0400-0500. Freezing rain possible. Feed heater tested and operational.

Charlie is out of state visiting family. Dana has on-call duty but she’s been pulling doubles all week. Use your judgment before waking her.

Good luck on your first solo night.

Active Services

Satellite	Customer	Service Type	Status at Turnover
AURORA-7	Meridian Shipping	Maritime VSAT	Operational

AURORA-7 is our only active service tonight. Meridian Shipping runs a fleet of cargo vessels in the North Atlantic. Their bridge crews rely on this link for weather routing, cargo manifests, and crew communications.

AURORA-7 Operations Reference

AURORA-7 is a legacy C-band satellite you’ve worked with before. It stopped north-south station-keeping three years ago to conserve fuel, which means its orbit is now inclined. From our perspective, it traces a figure-8 pattern in the sky over each 24-hour period.

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	7,100 (BUC)	1,047

Modem Configuration

Parameter	Value
Bandwidth	24 MHz
Modulation	QPSK
FEC Rate	3/4
TX Power	-7 dBm

Tracking Requirements

The antenna must actively follow the beacon signal to maintain lock. Program-track predictions assume the satellite holds perfect geostationary position - AURORA-7 does not.

Trouble Ticket

Ticket #: NOC-2026-0847

Opened: 0147 Local

Source: Network Operations Center (forwarded via Dana)

Priority: Medium

Customer Report:

Meridian Shipping reports intermittent connectivity on AURORA-7 service. Signal dropouts occurring every few minutes, lasting 10-30 seconds each. Bridge crew on M/V Northern Promise reports loss of weather routing data during transit.

Dana’s Note (text message, 0203):

“NOC just forwarded this ticket. Customer reports intermittent connectivity on AURORA-7, signal dropouts every few minutes. I’m on-call but heading back to sleep. You’ve got this.”

Weather Briefing

Current Conditions (0200):

Temperature: 28°F (-2°C)
Wind: NW at 12 mph
Precipitation: None
Visibility: 10 miles

Forecast (0400-0800):

Frontal passage expected 0400-0500
Freezing rain likely, accumulation 0.1-0.3 inches
Temperatures falling to 22°F (-6°C)
Wind shifting to N at 15-20 mph

Operational Considerations:

Ice accumulation on the antenna feed can degrade signal quality or cause mechanical binding. The feed heater prevents ice buildup but takes time to warm the components. Standard practice is to enable the feed heater proactively when freezing precipitation is forecast - don’t wait until ice is already forming.

Vermont Station Quick Reference

Equipment Status at Shift Start

Equipment	Expected State	Notes
GPSDO	Locked	Master timing reference - verify first
LNB	Powered, reference locked	Check for alarms
BUC	Powered, unmuted	Transmitting at handoff
HPA	Powered, enabled	Transmitting at handoff
Antenna	Tracking AURORA-7	Verify tracking mode
Feed Heater	Standby	Enable before freezing precip

10 MHz Reference Distribution

The GPSDO generates the master timing reference. All RF equipment locks to this signal:

GPSDO (source) → Distribution Amp → LNB, BUC, Modems

If the GPSDO shows locked but a downstream device shows reference unlocked, the problem is between them - usually the device itself needs a power cycle to re-acquire lock. After a power cycle the LNB needs about 90 seconds to warm up before it reads stable.

Power Sequencing

When enabling the transmit chain:

Verify BUC reference lock
Unmute BUC
Enable HPA output
Verify HPA power level

When disabling:

Disable HPA output first
Mute BUC
Power down as needed

Never enable the HPA with the BUC muted - the HPA sees no drive and the link won’t come up.

Loopback Testing

Before transmitting live RF, validate the low-power chain using BUC loopback mode. This routes the upconverted signal internally back to the receive path without radiating through the antenna.

Where the loop carrier lands: a C-band LNB only receives about 3.4-4.2 GHz, so it never sees the 6 GHz uplink itself and you do not retune it. The test loop couples the BUC output (about 66 dB down) through a loop translator that shifts it down by the satellite’s 2,225 MHz translation, so with the LNB LO left at 5,250 MHz the loop carrier shows up where our AURORA-7 downlink will:

Stage	Frequency
TX modem IF	1,047 MHz
BUC output (7,100 - 1,047)	6,053 MHz
Loop translator (6,053 - 2,225)	3,828 MHz
LNB IF (5,250 - 3,828)	1,422 MHz

View it at Center 1,422 MHz, Span 40 MHz, Min / Max Amp -100 / -30 dBm. The beacon stays at 1,085 MHz.

Drive level for the loop: tonight’s LNB runs 65 dB of gain, so it compresses at about -55 dBm in (output P1dB +10 dBm). At the standard 23 dB BUC gain the -7 dBm modem puts +16 dBm out of the BUC and -50 dBm into the LNB, well past that point (“LNB input overload”). Back the BUC off to 15 dB for the test (-58 dBm in, 3 dB under) and set it back to 23 dB before the HPA goes on.

What You’ll See:

CW Beacon: Narrow spike (unmodulated carrier)
Modulated Carrier: Wide “haystack” shape matching configured bandwidth
No Signal: Noise floor only - indicates configuration error or equipment fault
RX Analysis on the loop carrier: Effective C/N well under Raw C/N with ADC Status OPTIMAL, and the grey ceiling line (about 40 dB): the converter’s own limit, not a fault

A successful loopback confirms the TX modem and BUC are functioning. It does not test the HPA or antenna path.

Escalation Guidelines

Handle Yourself

Equipment reference lock faults (power cycle usually resolves)
Tracking mode configuration issues
Feed heater activation for weather
Spectrum analyzer configuration
Customer issues with clear technical causes

Wake Dana

Equipment failures requiring physical intervention
Safety-critical situations (RF hazard, facility security)
Multiple simultaneous major failures
Issues beyond your authorization level
Customer escalations demanding supervisor involvement

Dana made it clear she’s available for genuine emergencies. An LNB reference fault and a tracking mode issue are not emergencies - they’re routine troubleshooting.

Diagnostic Approach

When the NOC reports “intermittent connectivity,” don’t guess. Work the problem systematically:

1. Check the Dashboard

Alarms tell you where to look. Start there before diving into individual equipment panels.

2. Verify Timing

The GPSDO is the foundation. If it’s unhappy, nothing downstream will work correctly.

3. Check the Receive Chain

LNB powered and reference locked?
Beacon visible on spectrum analyzer at correct IF?
Antenna tracking mode appropriate for this satellite?

4. Check the Transmit Chain (if bidirectional)

VT-01’s receiver modem listens to our own AURORA-7 carrier, relayed back down by the satellite: it doubles as a loopback through the bird. If the beacon is steady but our carrier keeps dropping lock, the receive side is fine and the carrier is dropping out before it reaches the satellite.
A transmit level with nothing behind it reads “– dBm” (a muted BUC reads “MUTED”). If the Dashboard RF Chain shows BUC Output or HPA Power as “– dBm” for a moment while the HPA is enabled, the drive from the modem dropped out at that instant.
A faulted modem stays in the alarm list while it is powered: take it out of service (power it off) when you switch to the spare. Selecting a modem’s tab on the TX card only changes the view; the switch is powering the faulted modem off and bringing the spare up (it transmits only after the loopback test).
BUC reference locked?
Loopback test passing?
HPA enabled and not faulted?

5. Consider External Factors

Weather impact on signal?
Interference?
Satellite anomaly? (Check NOC bulletins)

Link Verification Checklist

A fully operational link requires all of the following:

Receive Path

LNB reference: Locked
Antenna tracking: Step-track (for AURORA-7)
Beacon lock: Acquired
Beacon signal: Visible at 1,085 MHz IF
Receiver: Steady lock on our own carrier (no dropouts)

Transmit Path

BUC reference: Locked
BUC mute: Unmuted
BUC loopback: Disabled, gain back to 23 dB
HPA: Enabled, nominal power

System

GPSDO: Locked
Dashboard alarms: None active
Feed heater: Enabled (if freezing precip expected)

End of Briefing

The customer is counting on you to diagnose and resolve this connectivity issue. Work methodically, trust your training, and document your actions in the trouble ticket.

If everything goes well, Dana will see the ticket resolution in the morning and you’ll have proven you’re ready for solo operations.

If it goes sideways, her number is in the on-call roster.