Converting to Concentration of CO in Air (parts per million)
The output of the waspmote to the database is a voltage reading, as can be seen from the circuit diagram below, this reading is affected by the input voltage, sensor resistance and load resistance.
To convert to ppm, the voltage reading is applied as follows
Step 1. Convert voltage reading to sensor resistance: Rsensor = Rload / ( Vcc - Vout) * Vout
Step 2. Normalise against resistance under air: Rsensor / Ro(Typical Resistance in Air)
Step 3. Compare normalised result against sensor response diagram:
Measurement of 0.9258v is observed (from our databases)