Antenna Stabilization Unit V2
High Altitude Airborne Two-Axis Gimbal Rated to 35,000 ft for Surveillance, GMTI and Image Tracking Missions
The Antenna Stabilization Unit Version 2 is the high altitude variant of the System Controls ASU family, rated for operation at both 30,000 ft and 35,000 ft at -40°C. Designed for positioning and stabilizing RF antenna payloads on aircraft platforms, it uses onboard INS data and a TMS-based DSP system for closed loop position, motor control and monitoring, maintaining antenna Line of Sight against aircraft yaw, roll and pitch with position accuracy better than 1 milliradian. Supporting strip map, spot mode, GMTI and image tracking applications via MIL-1553B and RS422 interface, it complies with MIL-STD-461E and operates on 28V DC with less than 100W peak power.
What is ASU-v2?
The Antenna Stabilization Unit Version 2 is an upgraded airborne two-axis gimbal system designed to position and stabilize an RF front end and antenna payload on aircraft platforms at altitudes up to 35,000 ft. Building on the Version 1 architecture, Version 2 extends the operational altitude ceiling and adds image tracking as a confirmed application capability alongside surveillance, avionic radar pedestal and tracking system uses. The system uses onboard INS data fed to a TMS-based DSP Antenna Control Unit for closed loop position control, motor control and monitoring, keeping the antenna aligned in azimuth and elevation regardless of aircraft heading and attitude changes.
| Parameter | Specification |
|---|---|
| Azimuth and Elevation Drive | |
| Number of Axes | Two (Elevation over Azimuth - orthogonal to each other) |
| Modes of Operation | Mode A: Strip Map, Mode B: Spot Mode, Mode C: Ground Moving Target Indication (GMTI) |
| Maximum Velocity Azimuth | 18 deg/second |
| Maximum Velocity Elevation | 18 deg/second |
| Minimum Velocity Azimuth | 6 deg/second |
| Minimum Velocity Elevation | 6 deg/second |
| System Requirements | |
| Maximum Roll Angle | Plus or minus 18 deg |
| Maximum Rate of Change of Roll Angle | 18 deg/sec |
| Maximum Pitch Angle | Plus or minus 10 deg |
| Maximum Rate of Change of Pitch Angle | 10 deg/sec |
| Maximum Rate of Change of Heading | 10 deg/sec |
| Maximum Yaw Angle | Plus or minus 10 deg |
| Yaw Rate | 10 deg/sec |
| Position Accuracy (Azimuth and Elevation) | Less than 1 milliradian |
| Orthogonality Between Two Axis | Less than 2 milliradian |
| General Specification | |
| Host Communication | MIL-1553B and RS422 |
| Weight | Less than 24 plus or minus 2 kg (excludes antenna) |
| Payload | Antenna disc 700x215x10mm, weight 6.0 kg |
| Fitment | Mounted on stiff back up plate of the gimbal; phase array on front side, strip line power divider and RF front end on backside |
| Supply Voltage | 28V |
| Protection | EMI/EMC conforming to MIL-STD-461E |
| Power Peak | Less than 100W |
| Power Average | Less than 50W |
| Environment Specification | |
| Temperature Storage | -40C to +70C |
| Temperature Operating | -40C to +55C |
| Thermal Shocks | -40C to +70C as a sudden change |
| High Altitude | 30,000 ft and 35,000 ft at -40C |
| Humidity Temperature Range | 30C to 60C |
| Relative Humidity | 85% to 95% |
| Operating Limits | |
| Limits of Travel (Dead Stop) Azimuth | -50 deg to +230 deg |
| Limits of Travel (Dead Stop) Elevation | -15 deg to +65 deg |
| Electrical Limits Azimuth | -47 deg to +228 deg |
| Electrical Limits Elevation | -12 deg to +67 deg |
| Software Limits Azimuth | -45 deg to +225 deg |
| Software Limits Elevation | -10 deg to +65 deg |
| Maximum Speed | 3 RPM |
| Operational Speed | 1 RPM |
Extended 35,000 ft Altitude Rating
ASU Version 2 is rated for operation at both 30,000 ft and 35,000 ft at -40°C, extending the operational ceiling beyond the 30,000 ft limit of Version 1. This higher altitude qualification makes Version 2 directly suitable for high altitude airborne surveillance platforms, long-range maritime patrol aircraft and other airborne systems that operate at or above 35,000 ft where Version 1 cannot be deployed.
INS-Based Autonomous Antenna LOS Stabilization
The ASU uses onboard INS data fed to a TMS-based DSP Antenna Control Unit to maintain antenna Line of Sight towards the designated area of interest against continuous aircraft yaw, roll and pitch motions. This INS-based autonomous stabilization enables the system to maintain precise antenna alignment independently throughout the surveillance mission regardless of aircraft manoeuvres, without requiring external attitude reference inputs.
Image Tracking as an Additional Application
Version 2 confirms image tracking as an operational application capability alongside surveillance, avionic radar pedestal and tracking system uses. This extends the deployment envelope of the ASU beyond radar antenna stabilization to electro-optical and imaging payload stabilization applications on high altitude airborne platforms, broadening the range of missions the system can support.
Sub-Milliradian Accuracy with Three-Layer Travel Protection
Position accuracy better than 1 milliradian with orthogonality between axes better than 2 milliradians is maintained against the full aircraft motion envelope of roll, pitch and yaw. Three independent travel protection layers, software limits, electrical limit switches and mechanical dead stops, protect the system across all operating and fault conditions, meeting the reliability requirements of high altitude airborne defence platform integration.
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Version 2 extends the altitude rating from 30,000 ft to 35,000 ft at -40°C and adds image tracking as a confirmed application. All other specifications are identical between versions.
Both 30,000 ft and 35,000 ft at -40°C, suitable for high altitude airborne surveillance platforms above the 30,000 ft ceiling of Version 1.
Strip map, spot mode and GMTI. Image tracking is an additional confirmed application in Version 2.
30,000 ft at -40°C. Operating temperature is -40°C to +55°C with thermal shock tolerance from -40°C to +70°C as a sudden change.
Less than 1 milliradian on both azimuth and elevation with orthogonality less than 2 milliradians, using TMS-based DSP closed loop control via onboard INS data.
Roll less than 18° at 18°/sec, pitch up to 10° at 10°/sec and yaw up to 10° at 10°/sec, maintaining antenna alignment against all heading and attitude changes.
MIL-STD-461E, with power peak less than 100W and average less than 50W on a 28V DC supply.
Azimuth software limits: -45° to +225°. Elevation software limits: -10° to +65°. Three protection layers: software limits, electrical limit switches and mechanical dead stops.
