X Net Strength is a small utility for monitoring the wireless signal strength of 802.11b cards under Linux. It is written in C and only requires xlib.
You can download it from the following link: https://packetstormsecurity.com/files/download/26383/xnetworkstrength-0.4.1.tar.gz
Source: https://packetstormsecurity.com/files/26383/xnetworkstrength-0.4.1.tar.gz.html