Portable Radar Timing: BRIDZA STW-PS Field Deployments

Application Note: Portable Timing for Field Deployments

Overcoming GPS-Denied Environments with the BRIDZA STW-PS and AERIS-10 Integration

Executive Summary

1. Field Challenges: The Imperative for Robust Portable Timing

Deploying sophisticated systems like radar in the field introduces a unique set of challenges that are often underestimated in controlled laboratory or permanent site environments.

* Power Scarcity and Management: Field sites lack reliable AC power grids. Operations depend on generators, batteries, or solar arrays, which introduce noise, voltage fluctuations, and finite runtime. Timing equipment must be highly efficient and tolerant of unstable power without compromising its performance. * Environmental Extremes: Devices are subjected to temperature swings from desert heat to arctic cold, high humidity, dust, sand, and vibration from transport or nearby machinery. Consumer-grade electronics fail under such stress, leading to data corruption and mission failure. * GPS Vulnerability: While GPS provides excellent timing, its limitations are stark in the field: * Urban Canyons & Dense Foliage: Buildings and trees block or reflect signals. * Indoor & Sub-surface Operations: GPS signals cannot penetrate structures. * Intentional Denial: Jamming and spoofing are common in electronic warfare (EW) and contested environments. * Intermittent Availability: Rapid setups during disaster response may not allow time for proper antenna placement and GPS signal acquisition. * The Portable Timing Need: The convergence of these factors demands a portable timing solution that is: 1. Self-Powered: Capable of operating for extended periods on internal batteries. 2. Ruggedized: Rated for wide temperature, shock, and vibration. 3. GPS-Independent: Features a highly stable internal oscillator (e.g., OCXO, Rubidium) that can maintain accuracy during GPS outages. 4. Rapidly Deployable: Simple, tool-less setup to synchronize systems within minutes, not hours.

2. BRIDZA STW-PS Overview: Engineered for the Field

The BRIDZA STW-PS (Stratum-1 Portable Timing Server) is specifically engineered to meet the demanding requirements outlined above. It is a self-contained, GPS-disciplined timing server built into a rugged, portable enclosure.

Key Specifications:

| Feature | Specification | Operational Benefit | | :--- | :--- | :--- | | Timing Output | GPS-locked <10ns RMS (1PPS). In holdover: <1µs over 24 hours (with OCXO option). | Provides laboratory-grade timing accuracy to field instruments, even when GPS is lost. | | Internal Oscillator | High-Stability OCXO (Standard) or Rubidium (Optional). | The core of GPS-denied timing. Maintains a precise clock for hours or days, ensuring data integrity. | | Battery Life | >12 hours with OCXO; >6 hours with Rubidium (with internal Li-Ion battery). | Supports full-day operations without external power. Hot-swappable battery packs extend mission time indefinitely. | | Environmental Rating | IP67; Operating Temp: -40°C to +70°C; MIL-STD-810H for shock/vibration. | Survives transit in rugged vehicles, deployment in rain, dust storms, and extreme temperatures. | | Connectivity | 2x Ethernet (with PoE), 2x 1PPS/10MHz, Serial. | Interfaces directly with radar, communication, and data systems. | | Size & Weight | < 8 kg in a pelican-style case. | Truly portable; can be carried by a single operator. |

The STW-PS is not merely a GPS receiver with a clock; it's a portable radar timing hub designed to be the reliable timekeeper for an entire field network.

3. AERIS-10 Integration: Seamless Synchronization for Mobile Radar

The AERIS-10 is a compact, software-defined mobile radar system used for perimeter security, drone detection, and tactical reconnaissance. Its performance is critically dependent on precise timing for coherent signal processing and accurate target plotting. Integrating it with the STW-PS is a model of field-friendly design.

Quick-Connect Interface: The AERIS-10 features a dedicated Time Sync Port with a standard BNC connector for 1PPS and a network port. The STW-PS provides a corresponding Quick-Connect Time Cable that bundles: * A 1PPS signal cable. * A 10MHz frequency reference cable. * A network cable for NTP/PTP time distribution. This single, ruggedized cable assembly connects both devices in seconds, eliminating field wiring errors.

Field Setup & Calibration Procedure: 1. Position Systems: Place the STW-PS with its GPS antenna having a clear sky view (initial setup). The AERIS-10 is positioned as per operational needs. 2. Power On: Activate the STW-PS first. The front panel display shows GPS acquisition status and oscillator health. 3. Connect & Synchronize: Attach the Quick-Connect cable. The AERIS-10 will automatically detect the external 1PPS and frequency reference. 4. Field Calibration: The AERIS-10's software interface will prompt a "Sync to External Time" routine. This takes approximately 30-60 seconds, during which the radar aligns its internal digital circuits to the STW-PS's precision references. A "LOCK" indicator confirms successful synchronization. 5. GPS-Denied Operations: Once synced, the STW-PS can be moved indoors, into a shelter, or its GPS antenna can be intentionally disconnected. The system seamlessly transitions to GPS-denied timing using its internal oscillator, maintaining lock with the radar.

Total Integration Time: From powered-off to fully synchronized and operational in under 5 minutes. This rapid setup is crucial for time-sensitive field deployments.

4. Use Cases: Timing Where It's Needed Most

a) Disaster Response & Emergency Management * Scenario: A major earthquake collapses urban structures. Response teams deploy AERIS-10 radars to monitor for survivor movements and structural shifts amidst rubble and temporary shelters. * Challenge: Urban canyons block GPS. Power is intermittent. Setup must be fast. * Solution: The STW-PS is placed on a vehicle rooftop for initial GPS lock, then carried to a shaded operational tent. The portable timing continues to feed the radar, allowing for coherent processing and precise location tagging of sensor data, even in a GPS-denied canyon. The team operates for a full 12-hour shift on battery.

b) Remote Scientific & Industrial Sites * Scenario: Monitoring wildlife activity around a remote mining operation or tracking glacial movement requires precise, synchronized data from multiple mobile sensors. * Challenge: No infrastructure, extreme cold, months between maintenance visits. * Solution: STW-PS units with Rubidium oscillators provide months of holdover timing after a single GPS synchronization at setup. They power down between measurement cycles to conserve the internal battery, waking on schedule to synchronize the field network for data collection.

c) Military Forward Operating Bases (FOBs) & Tactical Ops * Scenario: Establishing a defensive perimeter with counter-UAS (drone) radar at a temporary FOB. * Challenge: High probability of GPS jamming/spoofing. Frequent "jump" to new locations. Harsh, dusty environment. * Solution: The STW-PS's MIL-STD-810H rating ensures it survives rough transport. Its GPS-denied timing capability is mission-critical, allowing the AERIS-10 radar to maintain a coherent picture and track hostile drones even in a contested electromagnetic spectrum. The rapid 5-minute setup minimizes vulnerability during system deployment.

d) Large-Scale Event Monitoring & Security * Scenario: Providing security surveillance for a marathon or major public gathering using mobile radar units placed around the perimeter. * Challenge: Temporary site, crowded spectrum, need for precise data fusion between multiple radars. * Solution: One STW-PS per radar unit ensures all systems are synchronized to a common, precise time base. This allows security teams to accurately correlate tracks across overlapping radar coverage zones. If GPS signals are congested by the event's communications, the system holds stable.

5. Field Operations: A Practical Guide

Pre-Deployment Checklist: - [ ] STW-PS: Fully charge battery pack. Verify GPS antenna and Quick-Connect cable are in the case. Perform internal diagnostics (10-minute self-test). - [ ] AERIS-10: Update software/firmware. Verify radar antenna and mounting hardware. - [ ] Power: Confirm spare battery packs or external power source (e.g., vehicle 12V, generator) is available. - [ ] Environment: Review weather forecast. Have protective covers for extreme rain or sun.

Setup & Operation: 1. Initial Placement: Prioritize GPS signal acquisition for the STW-PS during the initial setup phase. 2. Cable Management: Route the Quick-Connect cable safely to avoid trip hazards and damage. 3. Monitor Status: Use the STW-PS front panel or its web interface (via laptop on the same network) to monitor: * GPS Status (3D Lock). * Oscillator Holdover Stability (TCXO/OCXO/Rb status). * Battery Percentage. 4. Holdover Management: If GPS is lost, note the time. The STW-PS will maintain accuracy within its specified holdover drift rate. Plan for a brief GPS re-acquisition (e.g., moving the antenna outside) if the mission extends beyond the holdover window.

Pack-Down: 1. Power down the AERIS-10. 2. Disconnect the Quick-Connect cable. 3. Power down the STW-PS and disconnect its GPS antenna. 4. Return all components to their cases. The entire process takes less than 10 minutes, enabling rapid redeployment.

6. Performance Validation: Stability Under Stress

The true test of portable radar timing is performance under field stress.

* Temperature Stability: The STW-PS's OCXO maintains a frequency stability of <±0.01 ppb over a -10°C to +55°C range. In practical terms, this means the 10MHz reference frequency—and thus the radar's coherent processing—remains virtually unchanged whether the system is in an air-conditioned command tent or sitting in the sun. This eliminates range Doppler measurement errors caused by thermal drift.

* Vibration Tolerance: Tested to MIL-STD-810H Method 514.8, the unit withstands vibrations typical of transport over rough terrain in a HMMWV or helicopter. This ensures that the critical oscillator's performance is not degraded by transport, a common failure point for less robust timing modules. The AERIS-10 radar, synchronized via a hard-wired cable, is inherently less susceptible to the micro-vibrations that can affect GPS antenna reception.

* Holdover Performance: In a documented field test, an STW-PS with an OCXO lost GPS lock at 14:00. The following morning at 06:00 (16 hours later), when GPS was restored, the time error was measured at < 4.2 microseconds. For most radar applications (resolution in nanoseconds to microseconds), this error is negligible, proving the system's capability to bridge prolonged GPS-denied periods.

Conclusion: Enabling the Mobile Era of Radar

The era of radar being confined to fixed, environmentally controlled sites is over. Modern operational demands require mobile radar systems like the AERIS-10 to be deployed wherever needed, whenever needed. However, the enabling technology for this mobility is often overlooked: timing.

The integration of the BRIDZA STW-PS with the AERIS-10 provides a comprehensive, field-proven solution to the critical challenge of portable timing. It directly addresses the core field problems of power, environment, and GPS dependency through its rugged design, long battery life, and precision holdover oscillator.

This combination empowers first responders, researchers, security professionals, and warfighters to deploy sophisticated radar capabilities in the most austere and challenging environments, secure in the knowledge that their system's timing—and therefore their data integrity and operational effectiveness—is uncompromised. For any organization looking to enhance its field-deployable sensor networks, investing in a robust, independent timing source is not an accessory; it is a foundational requirement for mission success.

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