Scenario 12 - LEOP: Commissioning

Shift Turnover Notes

Date: Wednesday 24 March, 0948 Local (Galway runs UTC in March) Station: GW-01 Galway, Ireland - NATS Europe Operator on Duty: You, solo LEOP Lead: Anneke Visser, MERIDIAN Constellation Operations (Rotterdam; countersigns the card) Customer: Erik Halvorsen, Nordic Maritime Watch (copied on the card; takes delivery of SAR-3 capacity when it is signed)

Morning SAR-1 tasking passes done. Both modems are still on SAR-1: RX 1,414, TX 1,405. Analyzer at its default, tracker parked where the morning left it, BUC muted, amplifier disabled. The only thing still on SAR-3 from Monday is the ACU beacon field. Rotterdam released the SAR-3 payload acceptance test plan at 09:40; the card is loaded on the console.

One pass, 10:06, nine and a half minutes. Eighteen minutes to make the station ready for it and predict the number. The scheduler will not offer a skip with the pass this close.

• Turnover note, 0945

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Acceptance Test Plan MER-ATP-SAR3-PLD-001

Cover note (A. Visser, 09:40):

Bus telemetry has been clean since Monday’s acquisition, so today is the payload. Readiness on the card first, both keys on record. Then on your 10:06 pass, in this order: chain up, PLD-ON, PLD-TEST-PATTERN, uplink secured, first decode on the video IF, chain down, results on the card. The TT&C console will accept those commands in any order. The card will not.

The predicted number goes on the card before AOS and the measured number goes beside it. Erik is copied. Whatever is in the Payload section when I countersign is the contract number.

Test Card (Working Document)

Section	Records
Readiness	Reference state, both crypto directions and both key states, the predicted C/N
Command	Checkout result: chain-up order, which commands, in what order, what the ACK pair proves
Payload	Measured C/N beside the prediction, and the difference
Verdict	Accepted or not, at what tested performance, with residual risk stated

Sequence

Step	Action	Evidence
1	Sweep: board, GPSDO, BUC reference	Clean board; reference on the card
2	Predict C/N at maximum elevation	Link Analysis prediction agrees with the card
3	Crypto both ways	TX encryption active, command key Valid; RX decryption active, traffic key Valid; on the card
4	Uplink: TX modem to 1,465 MHz; Doppler compensation engaged	TX chain reads 1,465.0 MHz
5	Analyzer centre 1,330 MHz	Beacon and pattern band both on screen
6	Tracker parked az 140° / el 5°	Slew done before AOS
7	Acquire: program-track, beacon on 1,315 MHz IF, chain cold	Beacon on RX analysis
8	Chain up in order: carrier into the muted BUC, unmute, HPA	Each step on its own; HPA linear
9	PLD-ON	ACK inside the window
10	PLD-TEST-PATTERN	ACK inside the window; Command line on the card
11	Secure the uplink: HPA output off	See the Aside below
12	First decode: RX modem to 1,340 MHz	Lock; C/N at or above 8 dB; Commit Link near max elevation with 4 dB margin; Payload line on the card
13	Chain down: BUC muted, carrier off	Mirror order, HPA already off
14	Verdict	Verdict line on the card
15	Deliver	Erik told what acceptance transfers

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Pass Plan and Command Window (epoch 09:48:00 UTC)

Item	Time
MERIDIAN-SAR-3 AOS	10:06:00 (az 140°)
Command window opens	10:06:22
Commit Link segment (4 dB margin available)	About 10:09:00 to 10:12:30
Max elevation 27.9°, slant range 764 km	10:10:45
Command window closes	10:15:08
MERIDIAN-SAR-3 LOS	10:15:29 (az 355°)

Northbound, 9.5 minutes. Three chain-up steps, two commands, a secure, a retune, a lock and a commit all sit inside it.

Other traffic	AOS	Max Elevation	LOS
MERIDIAN-SAR-1	10:50:01	25.2°	10:59:30
MERIDIAN-SAR-2	11:10:01	24.7°	11:19:28

Neither is part of the card. The scheduler offers a skip only after the SAR-3 pass.

Command Request

Item	Value
Target	MERIDIAN-SAR-3 (NORAD 61703)
Commands, in order	PLD-ON, then PLD-TEST-PATTERN once PLD-ON is acknowledged
Requirements	Uplink Doppler compensation engaged; key Valid; both ACKs inside the window

Command	Mnemonic	On the card
Payload power on	PLD-ON	Yes, first
Transmit payload test pattern	PLD-TEST-PATTERN	Yes, second
Start recorder playback	REC-PLAYBACK	No
Payload to safe mode	PLD-SAFE	No; not exercised on this card

Caution

The console does not sequence commands. PLD-TEST-PATTERN sent to an unpowered payload returns an ACK exactly like one sent to a powered payload; the ACK is receipt of the command, and the decode is the only evidence of its effect. Send them in the card’s order and record them in the card’s order.

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Acceptance Prediction (worksheet inputs)

Parameter	Value
Satellite EIRP	31.3 dBm
Slant range at max elevation	764 km
Free-space path loss at 11,760 MHz	171.5 dB
GW-01 receive antenna gain	50.4 dBi
System noise temperature	125 K
Occupied bandwidth	36 MHz
Miscellaneous losses	1 dB
Design figure, predicted C/N	~11.3 dB (worksheet must agree within 1.0 dB)
Demodulator threshold	4.2 dB C/N (QPSK 3/4: Es/N0 5.0 dB in the 30 Msps carrier)
Required margin at Commit Link	4.0 dB (C/N 8.2 dB), measured live

Reference: C/N = EIRP + G_rx − FSPL − L_impl − 10 log₁₀(k · T_sys · B), k = −228.6 dBW/K/Hz. EIRP is quoted in dBm.

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SAR-3 Link Parameters

LNB high-side: IF = LO − RF (13,100 MHz). BUC low-side: RF = IF + LO (12,600 MHz). The two sides of this rack do their arithmetic with opposite signs, and the same 60 MHz mistake is possible on both.

Signal	IF (MHz)	RF (MHz)	Format
SAR-3 telemetry beacon	1,315	11,785	CW
SAR-3 imagery downlink (test pattern)	1,340	11,760	QPSK 3/4, 36 MHz; band 1,322 to 1,358
SAR-3 TT&C uplink	1,465	14,065	QPSK 3/4, 36 MHz, −7 dBm modem. TX modem 1 is on 1,405 (SAR-1) and must be retuned
SAR-3 transponded return	1,290	11,810	The station’s own uplink, turned around; just off the left edge of a 1,330-centred screen
SAR-1 imagery downlink (for contrast)	1,414	11,686	What the RX modem is on now

Doppler: up to ±270 kHz on the downlink, up to ±325 kHz on the uplink; compensation at the TT&C console is required for an ACK.

Keys

Two keys, two directions. PLD-ON and the pattern command go up under the command key; the test pattern comes down under the traffic key. A pattern that will not decrypt looks exactly like a payload that did not power on, and the card cannot tell them apart afterwards. Both read Valid on the card before AOS, so the decode can only mean one thing.

Caution

Secure the uplink before you decode. SAR-3 turns the station’s own 14,065 MHz command carrier around through its command transponder at 11,810 MHz, co-polar with the receive chain and inside its band. With the amplifier up that return arrives some 50 dB above the test pattern, the AGC pulls the whole chain down and the video reads about 3 dB of C/N instead of eleven. Nothing on the RX chain is broken; it is doing what an AGC does. Both ACKs are in hand by then; the amplifier has nothing left to do until the next command.

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Transmit Chain Order

Up (inside the window, after the beacon is in)	Down (after the decode)
1. TX modem on air, into the muted BUC	1. HPA output off (already, before the decode)
2. BUC unmuted	2. BUC muted
3. HPA output enabled; confirm linear	3. Carrier off

Every stage sees a signal before it sees gain. An HPA enabled with no drive amplifies the noise floor into the feed; a BUC unmuted with the modem off does the same at lower level. HPA_NOISE_AMPLIFICATION is the invariant this order protects.

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GW-01 Equipment Status

Where the morning’s SAR-1 tasking left it, apart from the ACU.

Equipment	Status	Notes
4 m Ku tracker	Powered, manual, parked az 5° / el 3°	ACU beacon field preset 11,785 MHz from Monday. Park on az 140° / el 5° before AOS
Spectrum analyzer	Centre 1,414 MHz, span 60 MHz	Move to 1,330 MHz so 1,315 and 1,322 to 1,358 are both on screen
TX modem 1	1,405 MHz / 36 MHz / QPSK 3/4 / −7 dBm	Retune to 1,465 MHz. Not transmitting
BUC	12,600 MHz LO, reference locked, muted	Carrier goes in muted; unmute is step two of the chain-up
HPA	Powered, output disabled, 10 dB back-off	Step three of the chain-up; OFF again before the decode; stays off
RX modem 1	1,414 MHz / 36 MHz / QPSK 3/4	Still on SAR-1; the first decode is a retune to 1,340 MHz
LNB	13,100 MHz LO, reference locked	Stable
GPSDO	Locked, 9 satellites	Disciplined; on the card
COMSEC	TX encryption ACTIVE, command key Valid; RX decryption ACTIVE, traffic key Valid	Observe both; on the card
Link Analysis console	Acceptance card loaded, worksheet blank
Test card	Readiness, Command, Payload, Verdict	Blank

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Acceptance Checklist

Readiness (09:48 – 10:06)

• Test plan read; the order understood as the test, not a preference
• Dashboard: only the RX AGC no-carrier warning (noise only, empty sky), no faults; GPS Timing: GPSDO locked, no holdover; TX Chain: BUC on reference
• Link Analysis: worksheet computed, prediction agrees with the card
• TX Chain and RX Analysis: crypto active both ways, both keys Valid; Readiness line on the card
• TX modem 1 on 1,465 MHz; TT&C: uplink Doppler compensation engaged
• Analyzer centre 1,330 MHz
• Tracker parked az 140° / el 5°

In the Window (10:06 – 10:15)

• Program-track MERIDIAN-SAR-3; beacon on RX analysis at 1,315 MHz, chain cold
• TX modem on air into the muted BUC; BUC unmuted; HPA enabled and linear
• PLD-ON acknowledged
• PLD-TEST-PATTERN acknowledged, after PLD-ON; Command line on the card
• HPA output disabled: uplink secured before the decode
• RX modem 1 to 1,340 MHz; locked on the pattern; C/N at or above 8 dB
• Commit Link near max elevation with live margin at or above 4 dB; Payload line on the card

After LOS (10:15:29)

• BUC muted, carrier off
• Verdict line on the card, with residual risk
• Erik told what the signed card transfers

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End of Briefing

Two passes from Galway, one on Monday and one today, and MERIDIAN-SAR-3 goes from a launch provider’s estimate to a number on a contract. The number on the Payload line is the one every pass after this is measured against, and the Verdict line is what turns a bad pass next month into a ticket instead of an argument.

Anneke countersigns what you write. Erik tasks against it. Do the card in order.

Good luck.