The Luftsinn Sensor Engine consists of a small microcontroller running a lightweight Linux (Raspberry Pi 3) communicating using the serial interface, a Sensair K30 non-dispersive infrared sensor, a Bosch pressure-temperature-humidity sensor, and a real time clock (for maintaining an accurate time stamp for the log file when not connected to the internet). Coding for each unit is written in Python and includes scripts for local data logging as well as calling Post routines to the SQL database server at luftsinn.com.
Calibration
Before these units are deployed, they undergo extensive calibration to ensure accuracy and precision of reported CO2 concentrations as well as to collect pressure and temperature dependencies. When implementing the K30 NDIR unit used here, three factors must be accounted for: sensor offset, temperature sensitivity, and pressure sensitivity. Each parameter will be corrected through the implementation of experimentally determined calibration curves programmed into the unit’s software. Each Luftsinn unit undergoes a three-point calibration (0, 400, and 1000 ppm). Concentrations of the standards were confirmed with a cavity-enhanced absorption instrument made by Los Gatos Research.
The Luftsinn Database and Visualization Tools
On line sensors post to a database maintained on this server. Data access will include both mapping and charting options as well as "data dumps" into csv files for downloading.
Mapbox is a platform for creating rich, dynamic, fully customizable maps for all digital platforms. It is one of the biggest providers of custom online maps for major websites such as Foursquare, Pinterest, Evernote, the Financial Times and Uber Technologies. Since 2010, it has rapidly expanded and is now cornering markets in a variety of industries such as agriculture, transportation, and the U.S. Federal Government.
Mapbox has produced several open-source, mapping tools used in this project including mapbox.js, their open-source JavaScript library built on Leaflet, an open-source javaScript library for mobile-friendly, interactive maps. As such, mapbox.js supports web clients from mobile devices up through any of the modern browsers.
Charting is being implemented through d3 (data driven documents). D3.js is also a javaScript library for interactive data visualizations on the internet that is compatible with SVG, HTML5, and CSS standards.
page last edited February 6, 2018 by JHM