Understanding Wifi signals

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



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 )


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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