Editing Signal-to-noise ratio (section)

===Difference from conventional power===
In physics, the average [[power (physics)|power]] of an AC signal is defined as the average value of voltage times current; for [[resistive]] (non-[[reactance (electronics)|reactive]]) circuits, where voltage and current are in phase, this is equivalent to the product of the [[root mean square|rms]] voltage and current:
:<math>  \mathrm{P} = V_\mathrm{rms}I_\mathrm{rms}
</math>

:<math>
\mathrm{P}= \frac{V_\mathrm{rms}^{2}}{R} = I_\mathrm{rms}^{2} R
</math>
But in signal processing and communication, one usually assumes that <math>R=1 \Omega</math> <ref>{{cite journal |author1=Gabriel L. A. de Sousa |author2=George C. Cardoso |title= A battery-resistor analogy for further insights on measurement uncertainties |date= 18 June 2018 |url= https://doi.org/10.1088/1361-6552/aac84b |journal= Physics Education |volume= 53 |issue= 5 |pages= 055001 |doi= 10.1088/1361-6552/aac84b | publisher= IOP Publishing |access-date= 5 May 2021|arxiv= 1611.03425 |bibcode= 2018PhyEd..53e5001D |s2cid= 125414987 }}</ref> so that factor is usually not included while measuring power or energy of a signal. This may cause some confusion among readers, but the resistance factor is not significant for typical operations performed in signal processing, or for computing power ratios. For most cases, the power of a signal would be considered to be simply
:<math>
\mathrm{P}= V_\mathrm{rms}^{2}
</math>