Tough Challenges Test Creativity

The ClearMesh CM300 node provides high bandwidth wireless networking in a large-scale metropolitan environment. Roof, pole, or wall mounted outdoors, the optical heads had to achieve accurate aiming, be resistant to environmental conditions, manufactured at low cost, and designed for easy assembly.

Nectar’s Success: Experience-/Process-based Solutions

1. An enclosure with a passive thermal regulation system was designed to address either desert temperatures, which, combined with high solar loads, could create excessive heat masking infrared signals or cold temperatures, which could fog optics. Active cooling was not an option due to cost, power, and size.
2. FEA and CFD thermal simulation software tools were employed to evaluate thermal inputs and outputs, which enabled the team to rate and compare thermal management concepts to find target values for airflows and heaters, and to evaluate temperature gradients and its effects on part deformation.
3. Finite element analysis was used to minimize deflections and resonances early in the design process, which allowed for wide degrees of motion for the heads to aim, allowing flexible mounting of units at different elevations and positions scattered around the urban landscape.
4. Nectar developed a weather tight sealing system against wind propelled dust and water, allowing easy service access, and high degrees of differential thermal expansion between components.
5. Design facilitated the assembly process of the optical components. Bearing systems were specified, which used low cost materials and tooling, while providing low friction, zero play, and generous tolerances.
6. Nectar designed parts, assembly fixtures, and methods simultaneously to ensure that critical and most challenging assembly tasks were made as easy as possible, and minimized the number of fasteners and tools for assembly.
7. Field installation and service personnel were included during the design process to reduce shipping, logistics, and installation labor costs.
8. Design solutions reached via simulations were validated with working breadboards and mockups.
9. Functional testing was conducted both in the lab and outdoors.
10. Final production design employed die cast, injection molding, and extrusion fabrication processes. Specified materials were compatible with the temperature, UV, and moisture requirements.
11. Tolerance studies were performed and included on the final part drawings along with all critical inspection dimensions.
12. Nectar developed a form that allowed the CM 300 to integrate into rooftop or pole mount environments; the die cast magnesium enclosure integrates handholds and positioning markings to aid the installer.

Positive Results Exceed Expectations

The ClearMesh CM 300 was successfully tested in extreme weather locations like Chicago, where a record number of units were installed along major transportation corridors, linking government facilities and contractors. Units were engineered to resist extreme humidity, frost, wind, snow, and seismic events.