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Design
Commercial GNNS base stations from manufracturers such as Trimble, Leica, and Topcon are deisgned primarily for measurement accuracy and ease of use on temporary jobs sites. They are not built for long-term autonomous deployment in extreme heat, dust, wind.
After an extensive review of the current market options, our team concluded that no single commercially available prodyct integrates all of the four following capabilities: active forced-convection cooling that can remove 20 watts of internal heat at 45 C ambient temperature , true environmental sealing that allows airflow, airline-portable packaging, a universal layout that does not lock the users into specific electronic.
Design overview & Major subsystems
The core is a Pelican Storm Case IM2875, selected for its military-grade durability, integrated wheels/handle for portability, low conductivity HPC resin walls.
Thermal management system: A hybrid active/passive system. Passive elements include a UV-resistant tarp on a PVC frame (blocking ~90% of solar radiation). Active cooling is provided by a Montech NX400 heat sink and fan assembly (52 aluminum fins, 120mm fan) that forces air through the enclosure.
Structural mounting system: a heavy-duty aluminum tripod (collapsible to 1m) elevates the system while field added ballast (sandbags, steel plates) provides stability against 60km/h winds.
Cable & sealing system: All cable penetrations are localized to a single Icotek KEL modular cable entry frame, minimizing leak paths. An IP69K-rated breather vent prevents internal condensation and equalizes pressure during thermal cycling.
Design flow-chart
Thermal Management System: This subsystem utilizes a combination of passive conduction and forced convection.
An internal aluminum heat sink draws heat away from the electronics, while a high-static-pressure, IP68-rated fan drives airflow across the fins. This assembly ensures that the 20W internal heat signature is effectively dissipated through the ventilation ports.
Performance Overview, Simulations, & Test results
Simulation (ANSYS fluent)
Objective: Validate thermal performance under 20W internal load at 45°C ambient.
Method: Steady State CFD simulate modeling enclosure, ambient 45 °C (318.15 K), internal heat load 20W, heat sink, fan airflow (24m^3/hr.), and various vent configurations.
Vent configurations compared:
2-bottom
2-middle
4-bottom
1-top+2-middle
4-bottom
4-middle
2-bottom+2-middle
For a 20W heat load at 45 °C ambient, 24 m^3/hr airflow, the best thermal performance came from the four vent configuration ( two-bottom + two-middle intake ) and one bottom exhaust fan. This layout eliminated significant stagnant hot zones. Bottom vents alone gave the most uniform temperature distribution. Higher heat loads (up to 200W) can be managed by increasing airflow, though hot spots may need more attention.
The selected "2-bottom+2-middle" vent configuration produced the lowest volume average internal air temperature of 45.8 °C, a rise of only 0.8 °C above ambient. The simulation converged to a steady state average of 46.6 °C ( 319.8K). Mesh independence was verified.
This configuration produced the following results:
Max. volume average internal air temperature : 45.8 °C
Temperature rise above ambient : 0.8 C
Meets requirement ( <5 C difference )
Physical Testing
Thermal (Sauna) test
Multiple sensors were positioned at different locations to monitor temeparture distribution throughout the enclosure.
The enclosure was placed inside a sauna to evaluate its performance under elevated ambient temperature conditions.
Sensor temperature results from thermal validation test with calibrated initial temperature.
Sensor temperature results from thermal validation test.
Thermal sauna test under controlled 45°C environment showed a measured internal temperature of 46.8°C. The temperature rise above ambient 1.8°C ( within 0.2°C of simulation).
The measured temperatures closely matched the CFD simulation predictions, indicating that the enclosure provides sufficient thermal management and can operate reliably in elevated temperature environments.
IP5X (dust) testing
The test results showed less than 1 gram of fine perlite ingress. This represents a negligibe quantity ( <1%dust ingress), suggesting only minor incidental contamination.
IPX4 (water) testing
After following testing procedure, the test results showed no internal water pools or droplets. Although there was minor dampness on exterior seal area, this was deemed acceptable per IEC 60529 standard. All pentrations maintain IP54 sealing.
Summary of Physical testing and portability outcomes
Conclusion
No commercial product combines active cooling, IP54 sealing, airline portability, and a universal hardware compatibility. Our deisgn makes the necessary trade-offs: IP54 instead of IP67 , field-added ballast instead of shipped weight, volume cooling instead of component-specific attachment. We fervently aspire that our enclosure will contribute to preserving the cultural heritage by providing CHEI with a reliable. field-ready GNSS base stations for harsh environments on Earth!
Feel free to contact us with any questions or concerns.
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