OK, I finally received my SmartCitizen Starter Kit from Seeed today.
I am in a position to compare some readings from the Environmental Sensor I built myself and the new Smart Citizen device.
My own device has a Bosch BME 680 sensor and a HM3301 dust sensor both on separate Seeed Studios Grove type boards. Although different manufacture, these two devices are similar type and design to those in the SCK.
The system has been up and running about 6 weeks.
The SCK and my sensor are presently sited indoors in a bedroom adjacent to a window. Air conditioning system is off (but it was turned on earlier). I am in a residential suburb of Adelaide, altitude 110 M above mean sea level. Its 5pm on weekday where I live so traffic outside is relatively heavy because people have started coming home from work. Its beginning of winter and outside temp is around 15 deg C; weather is wet and windy today.
So, right now I have the following readings:
BME680 / SCK
Temp Deg C 19.85 / 19.8
R Hum % 55.22% / 57.2%
Pressure 1007.01 hPa / 100.8 kPa
eCO2 ppm 400.0 ppm / 400 ppm
VOC/tVOC 0.34 ppb / 0 ppb
HM3301 / SCK
PM1.0 ug/m3 2 / 1
PM2.5 ug/m3 3 / 3
PM10 ug/m3 9 / 4
So, the purpose of making the comparison is to ascertain if the new device readings make sense comparing to the ‘old’ device with different sensors.
They do. The readings are in the same ballpark anyway.
The ‘new’ SCK system is not yet burned in (requiring at least 2 weeks of continuous operation), I am assuming the sensors have the same self calibration characteristic as the BME680, so its possible the two sets of readings will become even closer in agreement.
The fact there are differences in the readings speaks to the obvious that sensors from different manufacturers will provide different readings. What one desires from a system such as SCK is consistency with reasonable accuracy, so as to be able to compare readings from different locations around the world. Absolute ‘scientific’ accuracy would seem to be a pipe dream however.
This is the contribution made by Smart Citizen, to have thousands of devices out in the world with exactly the same set of sensors. It has met its goal (IMO).