Why set a baseline in RT-PCR?

When we carry out RT-PCR, we can find that there will always be some background noise before the exponential growth period, of course, if your amplification signal is good enough, the impact of these noises on the subsequent exponential period, linear period, and platform period is very small, but it is undeniable that it will still have a certain impact on the curve in general. And the baseline setting is to reduce the impact of this noise to a certain extent, after the baseline setting, the machine will automatically deduct the background noise from each reaction hole. In general, the baseline is set in the first 15 cycles of the PCR amplification reaction, but sometimes due to the limitation of materials and other conditions, the time for the curve to enter the exponential period is advanced or delayed, and the baseline should be reset to ensure that the amplification curve is correct.  

The baseline is the horizontal part of the amplification curve and the signal is generated due to chance errors in the measurement.The baseline setting reduces the effect of background noise.