FD mark
FlatlineDynamics
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◀ SYSTEMS · REGISTRY/DOSSIER · FD-HMD1
EXTERNAL EVAL · B01
PROGRAMME 02 · OPTICS · TIER 1 · HELMET-MOUNTED HUD

SENTINEL
HMD-1 · B01

“Three modules. One cable. Zero compromise on signature.”

Sentinel HMD-1 is the optics tier of the Flatline loadout — a helmet-mounted display that puts situational and tactical awareness onto the operator's line of sight without the signature, weight, or interface penalty of commercial off-the-shelf. Sensor overlay, comms, navigation — fed off a single bus. B01 is the first architecture stable enough for external evaluation: optical geometry validated, firmware interface documented, display module replaceable without tools.

UNIT TELEMETRY
285G
HEAD-WORN MASS · 1 CABLE · 4-CONNECTOR REDUCTION
INTERFACEUSB-C · ONE BUS
MODULES3 · SERVICEABLE
DISPLAY · SWAPHOT · POWERED
OPTICAL · ADJNIL · BY DESIGN
FIRMWAREv0.4.1 · PUBLISHED
CONNECTORS1 · vs 4 TYPICAL
01
HUD VIEW · WHAT THE OPERATOR SEES
◢◤ FD-HMD1/REV.B01

What the operator sees.

Live HUD simulation. Select a scenario. The overlay reconfigures live across four mission profiles — friendlies, threats, waypoints, and vitals.
HDG 124°10M50M100M300M800MRNGELEV612MSLP 4°S338MWP-04 · RV412M BRG 116°S2 · 34°S4 · 68°COMMSA-NETGPSL1+L5 · 12 SVBATT86%FD-K25 BAY-03UP00:00
OPTIC · M-A LIVE· OVERLAY PASSTHROUGH
FOV 54° · IPD 64 · FW v0.4.1
FD-HMD1 · OPTIC RENDER · NOT PRODUCT PHOTOGRAPHY · NOT A MOCKUP
T+ 000.0
SCENARIO · OVERLAY MODE4 PROFILES
PATROL · situational sweep · low-signature
POWER · KEYSTONE BAY 03SHARED BUS
86%5.0V · 2.7A · DRAWING
SOURCE · FD-K25 / BAY-03 / 9.6AH PACK · ESTIMATED 60 MIN
TRACKED · 4SENSOR FUSION ACTIVE
FRS2AZ -34°22M
FRS3AZ +18°38M
FRS4AZ +68°64M
WPWP-04AZ -8°412M
02
SENSOR FUSION · WHAT FEEDS THE OVERLAY
◢◤ FD-HMD1/REV.B01

Nine inputs. One readout.

The processing unit fuses optic, thermal, illuminator, attitude, GPS, squad mesh, and the Keystone power-and-data bus into a single overlay. Latency under 16 ms end-to-end. Hover any input to trace its path.
M-C · PUFUSION< 16 MS E2EOPTIC OVERLAY · M-AOPTIC PASSTHROUGHOLED · 1920×1200 · 90 Hz90 HzTHERMAL MODULELWIR · OPT-TPM v130 HzNEAR-IR ILLUMINATORCOVERT FILL · PWM 1-100%CONTIMU · 9-AXISHEAD ATTITUDE · 1000 Hz1 kHzGNSS · L1+L5GPS · GAL · BEIDOU10 HzKEYSTONE BUSPOWER + SQUAD DATABUSSQUAD MESH · A-NET900 MHz · LoRa · 128 NODEEVENTOPERATOR PROFILEIPD · CAL · GLASSESSTATICTERRAIN CACHEDTED-2 · 12 KM RADIUSLOOKUPHELMET-SIDE INPUTSPACK-SIDE INPUTS
LATENCY · E2E
< 16 MS
OPTIC TO OVERLAY
INPUTS · ACTIVE
9 / 9
NO MISSING SENSORS
FUSION RATE
60 HZ
OVERLAY REDRAW
BUS · TO KEYSTONE
USB-C
POWER + DATA SHARED
03
ARCHITECTURE · MODULES
◢◤ FD/REV.B01

Three modules. One cable.

Three independently serviceable modules on a single USB-C bus. Power and data on one connection — deliberate departure from dual-bus designs that add weight and failure modes with marginal benefit at this form factor.
M-A
DISPLAY MODULE
M-A · OPTICAL OUTPUT
MASS82 G
CONNECTORUSB-C · POWERED
HOT-SWAP14 SEC · HOT
SERVICETOOL-FREE

Hot-swappable under power. Standard mounting geometry. Field-replaceable in 14 seconds — timed and verified at FD-LAB with 30 operators.

M-B
OPTICAL STACK
M-B · OPTICS
MASS68 G
CONNECTORINTERNAL · FIXED
HOT-SWAPBY DESIGN — NO SWAP
SERVICEVALIDATED · NO ADJ

Fixed geometry. Validated and documented — no measurable parallax at 3m. Adjustment points removed by design. What you see is the architecture.

M-C
PROCESSING UNIT
M-C · COMPUTE
MASS135 G
CONNECTORUSB-C · DATA + POWER
HOT-SWAPOFF-POWER
SERVICEM4/M3 HEX KEY

Off-the-shelf compute with a thin firmware layer. Interface published and version-controlled. Any firmware change that alters the interface increments the revision and ships a delta document.

BUS ARCHITECTURE · SINGLE CABLE · KEYSTONE 25 POWERED
KEYSTONE 25USB-C BUSM-C · COMPUTEM-A · DISPLAYM-B · OPTICS
4-CONNECTOR REDUCTION vs CONVENTIONAL · POWER + DATA ON ONE CABLE · NO SECONDARY HARNESS
04
FIELD RECORD
◢◤ FD/REV.B01

Verified and in service.

Verified claims against the current revision. Service and integration data. Firmware interface published as JSON-over-serial — chosen for legibility without specialised tooling; any change that alters the interface increments the revision.
▸ VERIFIED · 4 CLAIMS · B01
Optical axis geometry validated · no measurable parallax at 3m
Modular display module · field-swappable, 14 sec mean
USB-C power + data single-cable architecture
Documented firmware interface · JSON-over-serial protocol
▸ SERVICE · INTEGRATION
FASTENER DISCIPLINEM4 + M3 STAINLESS · ONE HEX KEY
SPARES KITFIELD SPARES KIT IN PROGRESS
PANEL ACCESSMODULAR: RAIL, COMPUTE, BATTERY
REPLACEABILITYEVERY COMPONENT, FIELD-SERVICED
INTERFACE DEFINITIONUSB-C SPEC PUBLISHED
PLATFORM COMPATHELMET-AGNOSTIC RAIL
HARNESS VARIANTSBACKPACK / WAIST · TBD
LOAD POINTSHEAD ≤ 480 G · HARNESS RATED
FIRMWAREv0.4.1 · PUBLISHEDICD: JSON-OVER-SERIALVERSION-CONTROLLED · DELTA DOC ON INTERFACE CHANGE
ICD ON REQUEST →
05
REVISIONS
◢◤ FD/REV.B01

Revision history.

Every trade stamped. Active prototype revision.
B01
CURRENT · INITIAL ARCHITECTURE
Initial architecture. Single-cable USB-C confirmed. Optical geometry validated.
2025.09
▸ DELTAS
STATUSCURRENT · ACTIVE
DISPLAYHOT-SWAP · 14 SEC
CABLEUSB-C SINGLE · CONF.
OPTICSGEOMETRY VALIDATED
DELTAONGOING · SEE TARGETS
▸ FINDINGS · WHAT THIS REV LEARNED
Display module hot-swap target met at 14 seconds. Weight and ambient light rejection targets remain open.
Optical geometry validated · no measurable parallax at 3m.
Single-cable USB-C architecture confirmed. No dual-bus requirement at this form factor.
Prior revisions documented in the lab notes.