There are two obvious ways to improve your SNR: Numerous smaller sources of noise in a small area, such as computers or cellular phones, can also raise the noise floor. The most common situations where low signal to noise ratio shows up is combination of weak input signal (or signal in your environment) combined with abnormally strong electrical currents nearby, such as transmission lines, generators, power plants, etc. Phenomenon such as wind, rain, snow, temperature, humidity, gravitational attraction of the moon, etc.The level of background noise in an environment depends on numerous factors, including: What Causes Low Signal to Noise Ratio?Īll real measurements are disturbed by noise. Your chances of winning drastically go down. Got all that? It can get even more complicated when you try and factor in SINAD to the mix, but we’ll stop there, as this is already getting far more complicated than you were likely hoping. This is expressed mathematically as a fourier transform. For example, your measured noise value (N) is 2 microvolts, and your signal (S) is 300 millivolts. Also, the resulting calculation is the SNR in decibels. However, if they are units of voltage, then you will multiply by 10.įor power, SNR = 20 log (S ÷ N) and for voltage, SNR = 10 log (S ÷ N). After this, if the signal strength measurements are in watts (power), multiply by 20. Then, take the common logarithm of the result, i.e., log (S ÷ N). Quite a good signal-to-noise ratio!įor more complex calculations, divide the value of the desired signal by the amount of the noise. For example, you measure a radio signal with a strength of -10 dB and a noise signal of -50 dB. The SNR is equal to the difference in the numbers. This is because when you subtract logarithms, it is the equivalent of dividing normal numbers. If your SNR measurements are already in decibel form, then you can subtract the noise quantity from the desired signal: SNR = S - N. SNR calculations can be either simple or complex. However, a voice-over network such as cellular or Voice-Over LTE will require a higher SNR value to provide reliably clear voice and high signal quality. A data network with 20 dB of SNR will still function relatively quickly. For example, data networks don’t require as high a ratio as voice, due to its speed being less critical to its function.
However, different networks will require different SNR levels to really function. These values were provided by Wireless-Nets. 5dB to 10dB SNR = No signal, almost never associated, agonizingly slow.10dB - 15dB SNR = Very low signal (1 bar).15dB to 25dB SNR = Low signal (2 bars).25dB to 40dB SNR = Very good signal (3 - 4 bars).>40dB SNR = Excellent signal (5 bars).Generally speaking, you want as high an SNR value as possible. Whether or not you have a good SNR value depends on what type of signal you’re working with. Raising the signal level will help in such situations. One of the great challenges in providing cellular, radio, and WiFi is providing enough signal strength to rise above any other forms of interference. The noise floor varies depending on the background noise in the environment. The higher the noise level, the less space there is for the actual data that is being transmitted on the channel. This means that for a given signal level, an increase in noise will decrease the data throughput. When SNR increases, the channel's data throughput also increases. This will degrade wireless throughput and latency as the retransmitted signals will take up airtime in the wireless environment. Signals close to the noise floor can be subject to data corruption, which will result in retransmissions between the transmitter and receiver. If the SNR value gets lower than one, the signal becomes unusable. The noise interferes with the signal processing capabilities of your network, causing random noise and amplitude modulation. With a lower value, you start to introduce Gaussian noise into your network (expressed as static), and as the number becomes closer to 1, the worse the static gets. In the most basic terms, SNR determines how usable your signal will be.Ī higher SNR value means the signal is clearer. The higher the value on one end in relation to the value on the other, the greater or lower your overall SNR value will be. It is, essentially, a balance beam between your signal power and noise power. Providing a definition of SNR can get very technical. Commercial What is SNR? Why is SNR Important?