Theβ parameter equals the amplifier’s offset plus ambient
light effect. It can be obtained by taking a reading without
IR emission. Under these conditions, this reading will
correspond with the value of the parameter β . A new
reading is taken immediately after IR emission is activated
By subtracting the previous reading, a signal without
offset β is obtained. Thus, the influence of all the light
sources, even fluorescent or incandescent lights, can be
removed. By naming this ‘cleaned’ signal as y, Eq. (1) can
be rewritten as