Air quality monitoring with 4G IoT

I have been experimenting with remote air quality monitoring using 4G and a Luftdaten type air quality monitor. These air quality monitors normally use an ESP8266 board which has built in Wi-Fi. If the monitor is within range of a Wi-Fi network this works very well. Sometimes this just isn’t possible though.

Wi-Fi is not always practical, 4G can be expensive

In one case, we wanted to monitor air quality at a school but it just wasn’t possible to connect to their Wi-Fi. I set up a 4G modem there but with a data SIM that cost £30 per month. Once the contract ran out I decided not to renew it. Currently the lowest cost data SIM is probably about £6 per month. Too expensive if you have a whole fleet of them.

IoT Solution

Lately, I have been looking into the possibility of air quality monitoring with 4G using an IoT (Internet of things) plan that uses the 4G network. IoT SIMs are designed for low data applications (perhaps a vending machine which orders more snacks when running low).

Luner IoT

I recently found a couple of companies that provide IoT services based on normal 4G on a nearly PAYG basis. I decided to order one from a UK based company called Luner for £7.19 including VAT and delivery. (But after you register it, they give you get £10 free credit) They charge £1 per month for the ‘line rental’ and 1p per MB. The estimated data cost for this solution will be about £1 per month. I send air quality and weather data to the international project and also to my own server. If I just sent the data to the project servers it would be even less.

Use a Mi-Fi

A Mi-Fi uses the 4G signal to create a personal Wi-Fi network. For the Mi-Fi itself, I bought a reconditioned one for £34.99. It is incredibly small and comes with a 7 hour battery. If you leave the battery out, you can run it continuously via a USB cable. This Mi-Fi does not need to be turned on or configured in any way. It was not even necessary to configure it. I only had to install the Luner micro-SIM into the device and then connected it to power via the included micro-USB cable.

I connected the Luftdaten to connect to the SSID of the Mi-Fi using the provided password. You can always change these values using its web based dashboard. Otherwise it works as it normally would. Note that you can still monitor your air quality sensor by connecting a phone or computer to your Mi-Fi and finding the monitor’s IP address. Be careful to use a low-data mode and to disconnect your phone right away to avoid extra data charges.

Next Steps for air quality monitoring with 4G

Since the Mi-Fi and the Luftdaten monitor are powered by a normal USB cable it is possible to power them from a phone charging battery. I am currently using a 20,000 MAh USB battery pack to power both the Luftdaten and it’s Mi-Fi. Will write another post when I have the results.

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