Signal-to-Noise Ratio

What is Signal to Noise Ratio?

In all kinds of wireless communication, there is a transmitted signal that is meant to be sent, but there is also various background noise. Some of the noise comes from the broadcasting machine itself, while other parts come from interference. When the noise overpowers the correct signal, the message is lost.

Wireless internet works a lot like sound and radio waves (after all, those are other forms of wireless communication). Imagine listening to a car radio. If you turn the radio up too loud, it will start to crackle and hiss, and you'll hear popping noises in the background. That's interference coming from the broadcasting machine. Usually it's too small to hear, but when you turn up the amplification loud enough, it too is increased.

When you try to tune into a station that's in another state, you only get static- that's because the radio waves have spread out in the great distance between you and the source. They've spread so thin that they're too weak to be picked up. Now the usually-quiet noise is stronger than the signal, so it gets picked up instead.

Lastly, imagine listening to a station that's coming through clearly, then driving under a thick concrete bridge. For a moment, while the bridge is between your antenna and the broadcasting source, the radio will cut out. That's interference due to a physical obstruction. The intended signal is blocked, and all that's left is natural background noise.

Natural background noise comes from all over. Every electronic device generates some small amount, and larger appliances and facilities generate a lot more. Part of it is even background radiation that exists across the entire universe! No area is free from all background noise.

Wifi Signal to Noise Ratio

In wireless networking, when the strength of the intended signal is so low that it's only as strong as, or even weaker than, the background noise and interference, problems arise. Your network will slow down considerably, or stop altogether.

Signal to noise ratio is abbreviated S/N or SNR. If the ratio is higher than 1:1, you have more signal than noise. Therefore, the higher your signal to noise ratio is, the better. Just like sound, the strength of a signal or noise is measured in decibels (dB), which you can track on your own computer.

In your utilities or control panel, you'll likely have a wireless diagnostic tool that can show you a real-time line graph of your signal plotted against your noise. You can also find the exact and average numbers they rank for you in negative decibels. Simply subtract the lower noise value from the higher signal value, and you've found your ratio.

Ideal Signal to Noise Ratio Values

  • 00 - 10dB: No signal. 0 bars. Wireless will not function.
  • 11 - 15dB: Barely a signal. 1 bar. Will be very slow.
  • 16 - 25dB: Low signal. 2 bars. Moderate speed.
  • 26 - 35dB: Good signal. 3 bars. Acceptable speed.
  • 36 - 45dB: Great signal. 4 bars. Very fast speed.
  • 46dB and up: Excellent signal. 5 bars. Lightning fast speed.

While a home setup may be easy, getting every computer in an office or facility up to these speeds can be challenging. That's why BCI is prepared to do it for you. To ask about your wireless audit, contact us today with the form below, or at (847) 615-2933.

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