[aprssig] APRS Air Quality Monitoring

[Steve Dimse]

> On Oct 12, 2018, at 12:00 PM, Robert Bruninga <bruninga at usna.edu> wrote:
> 
> Has anyone looked into the lower priced air-quality monitors that are out
> there? $50 to $250?
> 
Just a followup. I received my SDS011 from China in 10 days, for just over $22 with free shipping via eBay. It is a piece of cake to set up, comes with a naked USB serial dongle and cable. I plugged it into a Pi and with a few minutes of writing code I got it running. It outputs binary data so you can't just open it with a terminal program.

My first impression is very positive. The Pi is not on the internet to share live data but here is two hours.

http://www1.findu.com/aq.png

In this plot I was burning a candle to see if that adversely affected the air quality in the house, it did not. Then I blew the candle out, it smoked for 15 or 20 seconds, and the result is impressive. The sensor is about 5 feet from the candle, and it seems like the original plume of smoke was carried towards the sensor, causing a big spike that quickly resolved. The AC (it is still 85 in the Keys) then distributed the particles throughout the house air volume, and either dilution from window leakage or lung filter have been continuing to decrease it since.
> 
> What parameters are available and from that we can define an APRS format.

Go ahead, hopefully as a user-defined format.

This sensor reports particulate matter in two sizes: <2.5 and <10 microns, in units of tenths of ug/m^3, max is 999.9 and 1999.9 respectively (i.e. raw values to 9999 and 19999). Other elements of air quality are O3, CO, SO2, and NO2, but I'm not sure if those are worth adding to the format, perhaps only as options after the PM values as they will be much more expensive to monitor.

When you define it I can start sending it right away, though it may be a while before I have a weatherized version to give outside values. I may add findU support too.

> We can include radiation counts too...

No, that should be on a separate message. Most AQ stations won't be reporting this, keep them separate.

Steve K4HG