Understanding Wifi signals

This was originally a post on Mac Wifi signals however I’m now adding details about Ubuntu.

Ubuntu

wavemon is useful: https://askubuntu.com/questions/95676/a-tool-to-measure-signal-strength-of-wireless

However, it outputs a load of gibberish. i.e.

Link quality:

Signal level: (same as RSSI below I think)

Noise level:

SNR: Diff between Signal and noise

According to this https://forums.anandtech.com/threads/wireless-link-quality-vs-signal-strength-question.1013878/

Link quality = Signal to Noise Ratio (SNR)however, according to wavemon these aren’t the same.

According to this https://superuser.com/questions/866005/wireless-connection-link-quality-what-does-31-70-indicate quality is stored in a variable named rssi however, I see a link quality of 57% and I see an RSSI of -70 so they seem to bear no resemblance.

 

wavemon documentation is more gibberish. E.g. it starts by saying it’s an ncurses-based application. How on earth is that useful to checking your Wifi signal?!

And the initial page: https://github.com/uoaerg/wavemon

says zero about link quality. All it says is look at the man page. Which says slightly less than zero – all it says is:

Below, in the Levels section, you can see up to four bargraphs showing (1) relative signal quality with no explanation of what this graph might represent.

 

Mac

If your Mac Wifi seems to be struggling here’s how to find out more about what’s actually going on.

Signal strength:

The  Mac’s menu bar has a rudimentary set of signal strength icons. E.g.

which means practically nothing.

If it’s less than 4 bars you’re probably going to struggle. However, here’s how to find out more.

  1. Alt click the icon and look for RSSI (see also Mac: WiFi Diagnostics )

dBm

This is a negative dBm number which measures from 0 to -100 with 0 being perfect (and not realistic in everyday life) to -100 being no signal. Realistic values are:

-50: good

-60: reasonable

-75: poor

-100: no signal

So, if your WiFi is between -50 to -60 then your signal is OK.

If between -75 and -100 then you’re going to have problems. This article suggests RSSI > -60 for good WiFi (greater in the standard math sense – i.e. more positive rather than larger – e.g. -55 or -50 or -45). https://9to5mac.com/2016/07/14/how-to-understand-wireless-diagnostics-app-on-mac-to-analyze-improve-wi-fi-network/

and I personally see WiFi problems if <-70.

The same article suggests your Quality (Signal to Noise ratio – drawn in red in the middle) should be above 25.

If those aren’t good then decrease the distance between your wifi hub and your computer. Or get a mesh or extender.

 

Testing an Orbi Extender

Set up a different SSID.

WiFi Analyzer proved very useful.

Gives distance to Access Point in metres and dBM.

 

 

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