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Thanks to aspell and languagetool. Hand picked from these, there are too many strange things in the English language to be perfectly syntactical.
25 lines
2.1 KiB
Markdown
25 lines
2.1 KiB
Markdown
---
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id: non-aerial
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title: Non-aerial factors affecting transmission
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sidebar_label: Non-aerial factors
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slug: /hardware/non-aerial
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---
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Unless you're using your devices in a vacuum with clear line of sight between aerials the following will have an affect:
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- Weather (temperature, humidity & air pressure),
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- Transmission power, spreading and other associated channel factors,
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- Number of nodes within reach in the mesh (affects retries consequent duty cycle hit),
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- Absorption by materials (with varying degrees attenuation, by material and depth),
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- Reflection off surfaces (and channeled through material tunnels, including warm / cold air tunnels commonly present in the atmosphere),
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- Diffraction around obstacles (over forests and around corners).
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### Environmental factors
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For a bit of light reading on environmental research:
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- [RF attenuation in vegetation](https://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.833-9-201609-I!!PDF-E.pdf) (yes really); if you wander through the woods wondering how your RF is bouncing off leaves dependent on their variety, and wind speed … well you do, now.
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- [RF attenuation with various building materials](https://www.ofcom.org.uk/__data/assets/pdf_file/0016/84022/building_materials_and_propagation.pdf).
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- This one by ITU again is very detailed in its [analysis of the drivers of attenuation](https://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.2040-1-201507-I!!PDF-E.pdf) (I wasn’t aware that all EMF radiation exhibits reflection / transmission characteristics akin to light hitting a material boundary. So, depending on the angle of incidence, material and the EMF wavelength, it will be reflected and / or transmitted through).
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- These RF bands are also made more [noisy by adjacent LTE](https://www.ofcom.org.uk/__data/assets/pdf_file/0023/55922/lte-coexistence.pdf)
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In summary - wavelengths in Europe fair well in plain sight, curve over not-so-tall obstacles (including trees), reflect of surfaces at low angles of incidence. They go through humans without much attenuation; but not brick or stone or anything much above glass / Kevlar. Oh, and don’t sit under an LTE tower and expect it to be plain sailing.
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