One of the most frustrating issues with accessing the Internet is when we set up the router, everything should be working right - and you move into the next room and the signal turns to garbage. Upgrade the router — and the signal still doesn’t seem to get any better. Upgrade to a fancy mesh network, only to find people in the conference room still aren’t able to hook their laptops into the WiFi even though the signal should be strong.
The problem may not be signal strength or the range of the network. It could be an issue with what’s called “signal to noise”, sometimes referred as SNR for short by people who feel that there aren’t enough acronyms in our life or people who giggle when they get us to say “snore” out loud when talking about WiFi.
SNR is a real issue, though. If your network should be working well but downloads or slow, or there are odd disconnects in certain locations in your building, investigating SNR to find out if that’s what’s plaguing your connections is well worth the time.
Of course, the first thing when asking about how to fix “signal to noise ratio” issues is to delve into just what SNR means. Signal to Noise is a measurement of how much relevant WiFi signal there is compared to any other signals that can get in the way.
Usually, when dealing with WiFi issues, there are two main problems:
Think of each problem like a big room. If I’m on one side, and you’re on the other and you try to talk to me, if your voice is too soft I won’t be able to hear you unless you shout louder. That’s an issue with dead zones or signal strength.
Signal to noise is where we are in the same room, but the room is full of other people. As you try to talk to me, we have to complete with all of the noises other people are making. It doesn’t help if someone else has a voice similar to yours, so I have to figure out when it’s you talking versus someone else.
SNR isn’t a ratio, as in “there is 75% signal to 25% noise”, but is measured by taking the signal strength and subtracting the noise, not dividing it. Adding to the potential confusion is that the signal is measured in decibels. For those who work in audio, most people consider decibels a measure of sound as in how loud something is.
It gets worse. In WiFi, decibels are measured in negatives. If you remember old grade school math, negative numbers are the ones below 0. So if you have -15 dBm (deciBels per milliwatt), that is a stronger signal than -50 dBm. I know - it’s confusing, but once you get that the *higher* the number, the *weaker* the signal, the better off we’ll be.
Let’s take a look at two different rooms. In one, the average signal strength is -20, the noise is around -60. To get the signal to noise ratio, it’s the signal minus the noise, which means we have an average signal to noise of 40 in this case:
How about room 2, where the signal is also -20, but the noise is -25. Now our signal to noise is much lower — around 5:
Notice how difficult it is to tell the difference between the signal and noise lines on this chart compared to the first one? That’s the rule: the lower the signal to noise ratio, the worse communication will be. We want a nice, big number for our SNR or S/N ratio since that means there’s a lot of distance between our signal and our noise.
Remember that Signal to Noise ratio, sometimes referred to as S/N ratio, isn’t a “ratio” but the difference between the signal-to-noise. So the bigger the number, the better.
Most experts recommend that an SNR of 20 dB just for data - this is surfing the web, looking up charts and other related traffic. If you’re looking to stream high-quality videos or make good voice/video chats, then an SNR of 25 is going to be required. Here’s a list of what kind of Signal-to-Noise ratios to follow:
Of course, this will be determined by your basic bandwidth strength. If your bandwidth strength is only -5 dB and your noise is 0, then your Signal to Noise is great but your signal strength is still trash. So first make sure the signal is strong, then focus on the signal to noise ratio.
One of the most useful tools that works as a signal to noise calculator for macOS comes from NetSpot (unfortunately, NetSpot Windows users can't measure the signal to noise ratio, but the feature is on the roadmap).
For Mac users the process is so easy, it’s just a few steps:
Take our sample network. Here we have a signal of -39, and a noise of -80. So running this through our signal to noise calculator and we get (-39) - (-80) = 41. Or to save time, just look at the Level setting. If it’s green, the signal is clean.
Fixing Signal to Noise issues can take a multitude of approaches. First, get a WiFi signal analyzer. We’ve already mentioned NetSpot, and that’s a great place to start. It shows a list of all of the networks it identifies.
Once you see the list of WiFi signals, you can do a few things to increase the SNR ratio: