What is Signal to Noise Ratio?


Have you ever come across a listed product specification and seen an abbreviation “SNR” and asked yourself, “What does SNR mean?” although this specification may appear incomprehensible to the average consumer, the concept behind it is worth knowing as well as its impact on a system’s excellent sound quality.

What is Signal to Noise Ratio?

What Does SNR Mean?

“SNR” – also written as S/N – stands for “signal-to-noise ration.” It is a measure that is employed in engineering and science to compare how strong the level of the desired signal is to the level of the noise in the background. In other words, it is the ratio of the signal power to the noise power, often expressed in decibels (dB).

If the number is on the high side, it merely connotes a better specification because there is more helpful information i.e., the signal than undesirable data i.e., the noise. A negative number, however, implies that the noise is much stronger than the coveted signal.

To put it clearly, SNR compares the level of a Wi-Fi signal to that of background noise. Sources of this “noise” may include cordless phones, wireless game controllers, microwave ovens, wireless video cameras, fluorescent lights, Bluetooth devices, and so much more.

Take note, however, that “noise” in this context has nothing to do with co-channel interference from other radio transmitters. You will find this in the signal-to-interference ratio.

The Main Problems You Can Encounter When Dealing with Wi-Fi Issues

Two significant problems are associated with Wi-Fi issues, and they are as follows:

i. Dead spots

Dead spots are places where signals cannot reach, and this may be a result of the distance to the Wi-Fi device, the material the entire building is made of as well as other related issues. There is no way you can get a signal at a dead spot.

ii. Signal-to-noise ratio

Wi-Fi radio signals can be reached quickly with signal to noise, though there may be other radio signals that may make it harder to pick.

Why is Signal-to-Noise Ratio So Important?

Specifications for SNR can be found in several components and products that deal with audio such as headphones, wireless telephones (or otherwise), speakers, turntables, PC sound cards, receivers, tablets, radios, CD/DVD/media players, smartphones, microphones, amplifiers, and so much more. But not all manufacturers reveal this value to third parties.

The actual “noise” is characterized as an electronic or white static or hiss, and sometimes a vibrating or low hum. Try cranking the volume of your speakers to the max while nothing is playing. If you hear a hiss, that is the “noise,” which is sometimes known as a “noise floor.” This noise floor is always present.

What is a Good Signal to Noise Ratio?

A ratio of 41dB or higher is considered superior or excellent, while 25-40dB is deemed to be good or acceptable. A ratio of 10-15dB, however, is the accepted minimum for establishing an unreliable connection, and 16-24dB is poor. If you linger over the measurement markers that are on the map and take a look at the AP names on the left, you will see the precise ratios for each location.

But in Wi-Fi, decibels are usually measured in negatives. So, that means a -15 decibels per milliwatt (dBm) signal is much stronger than a 50 dBm signal. It is believed that this answers the question, “What is a good Signal to Noise Ratio?”

Communications engineers continually make attempts at maximizing the signal-to-noise ratio. Conventionally, this has been carried out by making use of the narrowest possible receiving-system bandwidth, which is consistent with the data speed that is desired. Nevertheless, there are other methods, as well.

In a few cases, the spread spectrum has been proven to enhance system performance. One can increase the signal-to-noise ratio by ensuring the source gets a higher level of signal output power if required.

How to Measure Signal to Noise Ratio

To measure Signal to Noise Ratio, it is first of all necessary to measure the root mean square of the noise alone. This can be measured using an oscilloscope or a True RMS multimeter. Alternatively, you can take several samples of the noise and then evaluate its root mean square.

An incredibly useful tool that works remarkably well as a signal-to-noise calculator is NetSpot. What is more, NetSpot is the only professional application for Wi-Fi site surveys, troubleshooting on both Windows and Mac OS X, and Wi-Fi analysis. It is also a free Wi-Fi analyzer that anyone can make use of, even without having too much tech knowledge.

Unfortunately, only macOS users can get to make use of this powerful tool, though NetSpot Windows users can find this feature on the roadmap.

So, if you are a Mac user and you want to know how to measure signal to noise ratio, you can follow these steps:

Step 1: Launch the NetSpot app.

Step 2: Select “Discover” (this is usually switched on by default).

Step 3: Select the Wi-Fi network whose signal to noise ratio you want to measure.

Step 4: Find the Signal and Noise levels.

Step 5: Take away or subtract Signal from Noise in order to get to the S/N.

You can also save a lot of time – instead of running through this calculation through NetSpot, the signal to noise calculator – by taking a look at the Level setting. If the setting is green, it means the signal is very clean.

Another reason why you should consider making use of NetSpot is that it can help to fix SNR issues quickly. The NetSpot app can show you a full list of the networks it readily identifies.

So, as soon as you see the list of Wi-Fi signals, you can take the following steps:

Get Rid of Extra Wi-Fi Networks

It is very common to find lots of Wi-Fi networks in a business environment. Of course, someone may decide to run a separate Wi-Fi network for one reason or the other, usually from their smartphone, etc. This is where the NetSpot app once again shows its remarkable strength.

The app can help you to trace the signal strength of other Wi-Fi networks so that you can remove them.

Check to See If There are Other Noisy Devices Close By

Is the router positioned next to a refrigerator, TV, fire alarm bell, or any other electronic device? If it is, you should endeavor to move the Wi-Fi router away a bit from these devices.

Switch Off the Signals You Don’t Need

Some Wi-Fi routers come with multiple bands, which range from 2.4GHz to 5GHz. So, if the 2.4GHz signal is not needed, you should turn it off because it is much more overcrowded compared to its 5GHz counterpart.


Avoiding products that have an abysmal signal-to-noise ratio should be paramount, though it shouldn’t be used as the only specification to determine the sound quality of some components.

Thanks to NetSpot, you can readily measure the signal-to-noise ratio, and that is why it is the best app out there today.

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Lucy Bennett

Lucy Bennett is a Contributing Editor at iLounge. She has been writing about Apple and technology for over six years. Prior to joining iLounge, Lucy worked as a writer for several online publications.