View Full Version : [all variants] Realtime Wi-Fi strength/noise-meter

November 18th, 2008, 12:08 AM
Hi there,

I'm setting up a network between an apartment on the second floor, and an apartment on the ground floor. I didn't think this would cause any problems - but it does!

Unfortunately I'm not able to use cables in this setup! And I can't mount the antennas outside, since I'm not allowed to mount anything on the outside of the building.

I have set up 2 directional antennas pointing at each other (not perfectly, yet) - But the signal is horrible.

Is there a tool in linux to measure the strength of a not yet connected network, in order to align the antennas?

Thank you in advance!

November 18th, 2008, 12:47 AM
Not sure if this is the best solution, but this is what I used when I was hunting for open networks in my flat.

# general:
sudo watch -n <delay between updates> iwlist <wireless interface> scan
# on my system:
sudo watch -n 1 iwlist wlan0 scan

EDIT: Just found out: you can filter the result by essid like this:

iwlist scan wlan0 essid <essid>

November 18th, 2008, 01:26 AM
Wow, iwlist seems effective! :)

It seems that iwlist doesn't respect the essid setting, though:

watch -n 1 'sudo iwlist wlan0 scan essid jazzen'

Note that I had to write the device before 'scan' for some odd reason.

That command outputs this: (among other)

Cell 02 - Address: 00:17:9A:58:DC:2F
Frequency:2.437 GHz (Channel 6)
Quality=55/100 Signal level:-75 dBm Noise level=-127 dBm
Encryption key:on
IE: WPA Version 1
Group Cipher : TKIP
Pairwise Ciphers (1) : TKIP
Authentication Suites (1) : PSK
Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s
9 Mb/s; 12 Mb/s; 18 Mb/s; 24 Mb/s; 36 Mb/s
48 Mb/s; 54 Mb/s
Extra: Last beacon: 1420ms ago

And that essid has nothing to do with 'jazzen' - which is the essid I'm interested in.

Any ideas?


I fixed it ad-hoc, though it's not that nice:

watch -n 1 'sudo iwlist wlan1 scan | grep -B 1 -A 15 "jazzen"'

But the response is not that good:

Quality=45/100 Signal level:-86 dBm

I've moved the antenna 20 meters - still on the ground-floor, so that it's directly below the apartment, and it increased the quality dramatically, but I still can't connect:

Quality=88/100 Signal level:-45 dBm Noise level=-127 dBm

What is the Signal level and Noise level readings? - and what should I be aiming at?