A tool to measure signal strength of wireless

On the command line you can use iwconfig and look for "Link Quality" and "Signal level" values.

When walking around with a netbook I often use this command which updates the output of iwconfig every second:

watch -n1 iwconfig

wavemon

A console app with color display and lots of easy to read information.

To install it enter the following commands:

 sudo apt-get update
 sudo apt-get install wavemon

To run it enter:

 wavemon

A prettier one:

watch -n1 "awk 'NR==3 {print \"WiFi Signal Strength = \" \$3 \"00 %\"}''' /proc/net/wireless"

Source: http://www.upubuntu.com/2012/06/display-wifi-signal-strength-in-real.html