Scenario 7 - Uplink Validation

Shift Turnover Notes

Date: Thursday, 0845 Local Station: Vermont (VT-01) Operator on Duty: You Supervisor: Charlie Brooks (off-site, main office) Shift Supervisor: Dana Torres (on-site, handling admin)

Overnight maintenance completed around 0300. HPA tube replacement and waveguide inspection - routine stuff. The transmit chain is powered down and needs validation before we resume normal operations.

Charlie’s stuck at the main office all day. Dana’s on shift handling paperwork. You’re expected to run this validation independently.

— Evening shift turnover

Charlie (phone call, 0830):

“Hey, it’s Charlie. Quick call - I’m stuck at the main office all day. Paperwork.

Overnight crew finished the HPA work. You need to validate the uplink before we go live. Standard post-maintenance procedure.

Dana’s on shift if you need anything, but you should be able to handle this. Mission Brief has the details.”

Active Services

Satellite	Customer	Service Type	Status
TIDEMARK-1	Teleport Services Inc.	Enterprise Data	Uplink offline (maintenance)

The transmit chain has been offline since midnight for scheduled maintenance. Customer traffic is routing through backup paths, but we need to restore VT-01 uplink capability before the morning traffic peak.

Maintenance Summary

Work Order: WO-2026-0127 Completed: 0300 Local Technician: Night maintenance crew

Work Performed:

HPA traveling wave tube replacement (scheduled)
Waveguide inspection and torque verification
BUC loopback test (maintenance verification)

Technician Notes:

“HPA swap complete, waveguide checks good. Ran loopback test to verify BUC output - signal looked clean. Powering down TX chain for day shift validation.”

TIDEMARK-1 Link Parameters

Frequency Allocation

Parameter	RF (MHz)	LO (MHz)	IF (MHz)
Beacon (Downlink)	4,175.5	5,250 (LNB)	1,074.5
Carrier (Downlink)	3,718	5,250 (LNB)	1,532
Carrier (Uplink)	5,943	7,000 (BUC)	1,057

IF Frequency Reference

Downlink (High-side LO):

IF = LO - RF

Uplink (Low-side LO):

IF = LO - RF

Modem Configuration

Direction	Frequency (IF)	Bandwidth	Modulation	FEC	Power
Receive	1,532 MHz	36 MHz	QPSK	3/4	—
Transmit	1,057 MHz	36 MHz	QPSK	3/4	-7 dBm

Spectrum Analyzer Settings (Beacon Acquisition)

Parameter	Value	Notes
Center Frequency	1,074.5 MHz	TIDEMARK-1 beacon IF
Span	2 kHz	Narrow for CW beacon
RBW	Auto
Reference Level	-50 dBm	Typical beacon level

Station Reference

Vermont (VT-01) - Current State

Equipment	Status	Notes
GPSDO	Locked	Timing reference stable
Antenna	Program-track on TIDEMARK-1	Verified by night crew
LNB	Powered, reference locked	LO: 5,250 MHz
BUC	Check status	Maintenance may have left in test config
HPA	Disabled	Enable after validation complete
RX Modem	Configured	Should be operational
TX Modem	Verify config	May need frequency adjustment

Uplink Validation Sequence

Post-maintenance validation follows this sequence. Each phase builds on the previous.

Phase 1: System Health Check

Before touching RF equipment:

Check Dashboard for active alarms
Verify GPSDO locked
Note any fault conditions

Phase 2: Receive Chain Verification

Confirm the receive path is operational:

Antenna tracking TIDEMARK-1
LNB powered, reference locked, thermally stable
Beacon visible at 1,074.5 MHz IF
Signal level nominal

Phase 3: Transmit Chain Configuration

Configure the TX modem for TIDEMARK-1 uplink:

Phase 4: Loopback Validation

Test the low-power TX chain before engaging the HPA:

Reduce BUC gain for loopback (prevents RX overload)
Enable BUC loopback mode
Unmute BUC
Verify loopback signal on spectrum analyzer
Confirm TX modem output is clean

Phase 5: Uplink Enable

After successful loopback validation:

Verify encryption status (AES-256 required)
Disable BUC loopback mode
Enable HPA output
Adjust HPA backoff for required output power
Verify uplink operational

Loopback Test Reference

Why Loopback First?

Loopback testing catches configuration errors before they cause interference. A misconfigured TX frequency or incorrect modulation settings are much easier to diagnose in loopback than by analyzing satellite return signals.

LNB Configuration for Loopback

To view the loopback signal at the same IF frequency as the TX modem output:

Parameter	Normal Operation	Loopback Test
LNB LO	5,250 MHz	7,000 MHz

Setting the LNB LO to match the BUC LO (7,000 MHz) allows direct IF comparison. The spectrum analyzer will show the TX modem output at 1,057 MHz.

BUC Gain for Loopback

Mode	Recommended Gain	Reason
Normal TX	50 dB	Full output to HPA
Loopback Test	20 dB	Prevents RX chain overload

Encryption Requirements

Parameter	Required Value
Encryption Mode	AES-256
Key Status	Valid

Escalation Guidelines

Handle Yourself:

BUC configuration issues (mute state, loopback mode, gain)
TX modem frequency and parameter configuration
Loopback test execution
HPA enable sequence
Reference lock faults (power cycle usually resolves)

Inform Dana:

Equipment faults that don’t clear after troubleshooting
Unexpected alarm conditions
Validation complete (so she can update the shift log)

This is standard post-maintenance validation. Work methodically through each phase.

End of Briefing

The overnight crew did their part - the hardware is ready. Now you need to verify the configuration and bring the uplink back online.

Charlie’s not here to walk you through this one. Dana’s available if you need her, but she expects you to handle routine validation independently.

Work through the sequence: check for alarms, verify receive, configure transmit, test with loopback, then bring it live. Document any issues in the maintenance log.

When you’re done, VT-01 will be back at full capability and the customer traffic can route normally again.

Time to prove you’re ready.