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Open-source technology offers expansion of satellite validation capability

11 March 2021

Solar-tracking radiometry for all: PML publishes open-source hardware and software for the solar-tracking radiometry platform (So-Rad). 

So-Rad in use

Observing water colour (reflectance) allows researchers to assess the presence of phytoplankton, suspended solids and dissolved organic matter in inland, coastal and ocean waters. The automated, open-source So-Rad (solar-tracking radiometry) platform significantly lowers the cost of collecting ground truth to validate these observations made by satellites. 

One of the best ways to increase the volume of useful water-leaving reflectance observations is to mount radiometers on a turning platform. Thus far only experimental and closed-source commercial solutions existed, neither of which were sufficient to achieve the ambition of delivering continuous, quality-controlled satellite validation data around the world. 

With the So-Rad, PML provides owners of commercially available radiometers the possibility to upgrade fixed-angle systems. A step-by-step build guide is now available through the So-Rad page on the MONOCLE website. The build guide includes hardware and software components including CAD diagrams for both electronics and machining. All materials are published under a Creative Commons Attribution-Non-Commercial license. 

Some key features of the So-Rad include: 

  • Low power consumption (15W) 
  • Viewing angle adjustment for solar position and platform heading, suitable for ships and (large) buoys
  • Tilt/pitch/roll monitoring 
  • Local data buffering for fully autonomous operation 
  • Configurable operating range for viewing angle, solar elevation, and measurement intervals: no  need to collect data under suboptimal conditions
  • Control software written in Python 3, modular design to extend e.g. additional sensor support
  • Local (WiFi) and remote (LTE) monitoring

Related information

Find out more at the So-Rad page on the MONOCLE website

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