Signal To Noise Ratio

Signal to noise ratio that tells one how immune the system is to random interference. Any electric signal, however technically advanced, always picks up some interfering signal. This interference signal causes disturbance in the original output of the system. Note that the word output is used in place of image because interference is a phenomenon that is not only restricted to the camera system but is associated with all electric circuits. If the interference is very high the output can be distorted beyond recognition. Because of this reason it assumes great importance in deciding the quality of the output of the system and hence, the system itself.

This interference, commonly referred to as Noise, is expressed in all the manuals of any electric product. It is expressed in terms of its proportion in relation with the actual wanted signal. Electric signals are expressed in a unit called decibels (dB). Thus, noise also being a electric signal (unwanted), is also expressed in the same unit. An accepted form of expressing the proportion of noise in relation with signal is Signal to Noise Ratio (SNR). Simply put, it says for how much part of wanted signal, there is one part of noise. Calculated simply by putting total signal decibels in the numerator’s place and total noise in the denominator’s place, this ratio provides adequate insight into the quality of output. SNR does not have any unit because both the numerator and denominator have the same unit. It should be obvious that higher the SNR, better is the system. This feature of the system gets lots of focus from sales personnel of all the different companies. This specification is a function of design of the circuitry and hence solely in the hands of the manufacturer. Better design and use of better components ensures minimum noise. It should be noted that no system can ever have nil noise.