ULS-XSpot-G3 Interface Control Document

ULSDC-PBICD190426 · version 0.1.6 · issued August 9, 2026
The numbered PDF is the controlled copy: download it from the portal.

Introduction

Purpose

This document defines the interfaces between ULS-XSpot-G3 components, including one tether-compatible transmitter (ULSDV-XS-G3-TX) and 2 identical, equal-priority RXM receivers (ULSDV-HLXS-G3-RXM). The dual RXM architecture is used for redundancy and for yaw orientation estimation using a triangular method in MRX mode.

ULS-XSpot-G3 shares the HL/XS G3 platform with ULS-Heli-G3. Optical, electrical, and communication interfaces are identical to ULS-Heli-G3; the only difference is the transmitter case, which has a centre through hole for tether cable passage.

Scope

This document is intended for system engineers, integrators, and developers working with ULS-XSpot-G3 systems in tethered drone applications.

Assumptions and Exclusions

• This document defines interfaces only; product selection and overview information belong in the datasheet.
• Installation, calibration, and operating procedures belong in the operation manual.

System Components

Transmitter (Ground Unit)

The ULS-XSpot-G3 transmitter (ULSDV-XS-G3-TX) is the ground-side unit that emits the optical IR positioning field. It uses the same optical, electrical, and communication design as the ULS-Heli-G3 transmitter (ULSDV-HL-G3-TX); the only difference is a through hole in the centre of the case that allows the tether cable to pass through the unit.

• Device code: ULSDV-XS-G3-TX
• Primary function: Optical IR field emission for precision positioning
• Optical emission parameters: 940nm, pulsed
• Tether-compatible design: centre through hole (47 x 47 mm) for tether cable passage

Figure: ULSDV-XS-G3-TX Transmitter

Receiver (Onboard Unit)

The ULS-XSpot-G3 uses the shared ULSDV-HLXS-G3-RXM receiver unit, identical to the one used in ULS-Heli-G3.

• Device code: ULSDV-HLXS-G3-RXM
• Primary function: Optical IR field sensor for precision positioning
• Optical central wavelength: 940nm

System architecture uses 2 identical RXM receiver units operating with the same priority.

Both RXM units are used for redundancy and for yaw orientation estimation using a triangular method in MRX mode.

Figure: ULSDV-HLXS-G3-RXM Receiver

RS422–UART Onboard Adapter

When the autopilot has only a UART interface, the ULSDV-HLXS-G3 RS422-to-UART adapter (ULS-XX-UART-RS422) is used onboard to connect the ULSDV-HLXS-G3-RXM receiver to the autopilot.

Figure: ULS-XX-UART-RS422 Onboard Adapter

USB–RS422 Ground Adapter

The ULS-XX-USB-RS422 adapter is used on the ground to connect the ULSDV-XS-G3-TX transmitter to a PC for configuration and control.

Figure: ULS-XX-USB-RS422 Ground Adapter

Interface Overview

Figure: ULS-XSpot-G3 System Interfaces Overview

Interface Summary

• Transmitter to control PC
• Transmitter to receiver optical link
• Receiver to autopilot, PC, and network interfaces
• Power distribution and interface-related electrical constraints

Physical Interfaces

Figure: ULS-XSpot-G3 Physical Interfaces Overview

Transmitter to Control PC Interface

The transmitter (ULSDV-XS-G3-TX) connects to a PC via the ULS-XX-USB-RS422 ground adapter for configuration and control.

Figure: ULS-XX-USB-RS422 Adapter Pinout

*Table: ULS-XX-USB-RS422 Pinout *

Data Types

• Status information
• Control signals
• Transmitter configuration
• External IMU/COMPASS data

Connection Types

• CAN Bus – For network communication
• USB – Via ULS-XX-USB-RS422 adapter (PC side)
• RS422 – Native transmitter interface; for serial communication with external sensors

Transmitter Pinout

ULSDV-XS-G3-TX Transmitter pinout information.

Figure: Transmitter connector

Table: Transmitter Connector Pinout (ULSDV-XS-G3-TX)

The transmitter connects to a PC via the ULS-XX-USB-RS422 ground adapter (USB side to PC, RS422 side to transmitter connector).

Transmitter to Receiver Interface

The transmitter and receiver use an optical interface to exchange data. Transmission uses pulsed IR emission at 940 nanometers. Data transmission is only in the direction from the transmitter to the receiver.

Data Types

• Position encoded
• Status encoded data (transmitter orientation and instructions)

Connection Type

• Optical IR 940nm (pulsed) – Infrared optical link

Receiver Interfaces (RXM Set A and RXM Set B)

Both RXM receivers (ULSDV-HLXS-G3-RXM) are identical and have the same priority in system operation.

When the autopilot provides only a UART interface, connect the RXM receiver RS422 output through the ULS-XX-UART-RS422 onboard adapter.

Figure: ULS-XX-UART-RS422 Adapter Pinout

Table: ULSDV-XX-UART-RS422-R0 4 pin connector pinout

Table: ULSDV-XX-UART-RS422-R0 6 pin connector pinout

Data Types

• MAVLink messages
• ULS-Blitz frames
• ASCII protocol
• MRX-mode yaw estimation data (triangular method)

Connection Types

• RS422 – Native receiver interface
• UART – Via ULS-XX-UART-RS422 adapter (for UART-only autopilots)
• CAN – Network communication
• USB – Direct PC connection

Receiver Pinout

ULSDV-HLXS-G3-RXM Receiver pinout information.

Both receivers (Set A and Set B) are identical, equal-priority units. The pinout is the same for both.

Figure: Receiver connector

Table: ULSDV-HLXS-G3-RXM Connector Pinout When the autopilot provides only a UART interface, connect the receiver RS422 output to the autopilot via the ULS-XX-UART-RS422 onboard adapter.

For receiver setup unscrew protection part to get access to usb connector.

Figure: Receiver USB connector

Electrical Interfaces

Figure: Power Distribution and Connections

Transmitter Electrical Characteristics

Table: Transmitter Electrical Specifications Tethered System Power: Transmitter may be continuously powered from a ground station power supply via the tether cable.

Receiver Electrical Characteristics (Per RXM Set)

Table: Receiver Electrical Specifications

Communication Interfaces

Supported Communication Methods

• Optical IR 940nm pulsed link between transmitter and receiver
• RS422 for native wired subsystem interfaces
• UART via ULS-XX-UART-RS422 where required by the host autopilot
• CAN for network communication
• USB for direct PC access where supported

Data Definitions

Data Categories

• Position-encoded optical data
• Transmitter status and orientation data
• MAVLink messages
• ULS-Blitz frames
• ASCII protocol data
• MRX yaw estimation data

Message payload definitions are given in ULSDC-PBDS051125-ULS-DeCoNet Blitz Messages Specification.

Functional Interfaces

Figure: Data Flow and Functional Interfaces

Data Exchange

The ULS-XSpot-G3 system data exchange mechanism, applied to tethered drone operations:

Control PC Functions:

• Configure and view status of transmitter
• Set configuration of receivers
• Send control signals (On/off, compass override information)
• Monitor tethered operation parameters

External Equipment:

• External IMU/Compass equipment can be used to override internal IMU/compass information
• Tether management system integration for position reference

Receiver Functions:

• Accept data from transmitter over IR signal (position field information and ground unit IMU data)
• Accept NED and Attitude information from autopilot to convert coordinate system
• Multiple receivers (MRX mode) communicate to calculate vehicle orientation (YAW) using triangular method
• Send position offset data to autopilot
• Support for tethered flight modes and station-keeping

Mechanical Interfaces

Table: Mechanical Dimensions

Figure: ULSDV-XS-G3-TX Projection Views (Color)

Figure: ULSDV-XS-G3-TX Transmitter Dimensions

Figure: ULSDV-HLXS-G3-RXM Projection Views (Color)

Figure: ULSDV-HLXS-G3-RXM Receiver Dimensions

The transmitter centre through hole (47mm x 47mm) is reserved for tether cable passage. Do not route the tether cable across the optical emission apertures.

Environmental Conditions

Equipment is designed to meet stringent military and maritime operational requirements, providing reliable performance in the most demanding environmental conditions including shipboard operations, offshore platforms, and tactical deployments.

Operating Temperature Range

• Extended operating range: -40°C to +85°C
• Meets MIL-STD-810 requirements for temperature extremes
• Arctic to desert operations capability
• No performance degradation across full temperature range
• Qualified for rapid temperature transitions and thermal shock
• Cold-soak start capability from -40°C

Humidity and Salt Fog Resistance

• Relative humidity: Up to 95% (condensing)
• Salt fog resistant per MIL-STD-810 Method 509
• Maritime environment qualified for shipboard operations
• Corrosion-resistant materials and protective coatings
• Protected against salt spray and marine atmosphere
• Suitable for offshore platform installations

Ingress Protection

• IP67 rated (Dust tight and water immersion resistant)
  • 6 - Complete protection against dust, sand, and particulate ingress
  • 7 - Protected against temporary immersion in water (up to 1 meter depth for 30 minutes)
• Exceeds requirements for shipboard and maritime operations
• Protected against:
  • Heavy rain and sea spray
  • Temporary submersion (deck washing, wave impact)
  • Sand and dust storms
  • Contaminated environments

Shock and Vibration

• Vibration: MIL-STD-810 Method 514
  • Helicopter vibration profile qualified
  • Shipboard vibration and shock resistant
  • Continuous operation during vibration
• Mechanical Shock: MIL-STD-810 Method 516
  • Drop and impact qualified
  • Transportation and handling shock resistant
  • Crash survival design considerations

Electromagnetic Compatibility

• EMI/EMC: MIL-STD-461 compliant
  • Electromagnetic interference immunity
  • Low electromagnetic emissions
  • RF coexistence with military avionics
  • Lightning protection per MIL-STD-464
• ESD Protection: IEC 61000-4-2
  • Contact discharge: ±8kV
  • Air discharge: ±15kV

Storage Conditions

• Storage temperature: -55°C to +85°C
• Relative humidity: Up to 95% (condensing)
• Long-term storage in uncontrolled environments
• Sealed for preservation and long-term depot storage

Altitude and Pressure

• Operating altitude: -500m to +4500m above sea level
• Storage altitude: -500m to +12000m
• Pressure differential resistant
• Suitable for high-altitude helicopter operations

Maintenance and Serviceability

• Designed for field maintenance and repair
• Minimal preventive maintenance required
• Accessible components for service and inspection
• Environmental seals serviceable in the field
• Long service intervals suitable for deployed operations

Note: All environmental specifications are subject to final qualification testing. Contact UAVLAS for the most current test data and certification documentation. Custom environmental testing and certification to specific standards available upon request.

Optical Radiation Safety (IR Emission)

The transmitter (ground unit) emits pulsed infrared optical radiation with a centre wavelength of 940nm. The receivers are optical sensors only and do not emit optical radiation.

Why This Warning Is Given

Radiation at 940nm is outside the visible range. The protective mechanisms that limit exposure to bright visible sources — the blink reflex, pupil constriction, and the instinct to look away — are not triggered by an invisible source. Exposure time is therefore limited only by operator behaviour, which is why the precautions below are given as operating instructions and not left to the operator’s judgement.

The transmitter is a positioning beacon. It is not an illumination product and is not intended to be viewed at any time.

Operating Precautions

• Do not look directly into the transmitter emitter apertures from a distance of less than 1 metre while the unit is powered.
• Treat the transmitter as emitting whenever supply voltage is applied, including when no receiver is present and no positioning data is being transferred.
• Switch emission off before working directly in front of the transmitter. Use the Illumination parameter in ULS-Tools to disable emission, or disconnect supply power.
• Do not view the powered transmitter through binoculars, telescopes, camera lenses, magnifiers, or any other light-collecting instrument. Such optics concentrate the emission and can raise the exposure at the eye by orders of magnitude compared with unaided viewing.
• Do not add, remove, or modify optical elements of the transmitter. Added optics change the emission characteristics and invalidate any photobiological classification of the unit.
• Position the transmitter so that the emission field is directed away from work positions and walkways where personnel stay for extended periods.
• Servicing personnel working inside the emission field at close range should disable emission first rather than rely on viewing distance.

Classification and Applicable Standards

Table: Optical Radiation Safety Data

For a 940nm source the applicable exposure limits are the retinal thermal hazard (380nm to 1400nm), the retinal thermal hazard for a weak visual stimulus (780nm to 1400nm, which applies specifically to sources that give no visual cue), and the infrared hazard to the cornea and lens (780nm to 3000nm). The corneal and lens limits are intended for chronic exposures longer than 1000s at a daily averaged irradiance of 100 W/m² or more.

Organisations operating this equipment within the European Union are additionally subject to Directive 2006/25/EC on the exposure of workers to artificial optical radiation, which requires the employer to assess worker exposure against the exposure limit values given in Annex I of that directive. UAVLAS provides the emission data needed for that assessment on request.

Integration Wiring Diagrams

Figure: HL/XS G3 Ground-Side Wiring Schematic

Figure: HL/XS G3 Onboard Wiring Schematic

Part Numbering

Table: Part Numbering

Applicable Documents

• ULSDC-PBDS190426-ULS-XSpot-G3-Datasheet
• ULSDC-PBOM190426-ULS-XSpot-G3-Operation-Manual
• ULSDC-PBDS051125-ULS-DeCoNet Blitz Messages Specification

Change Control

All changes to this document must be reviewed and approved by the relevant technical leads and stakeholders