With inSSIDer, you can inspect your Wi-Fi and surrounding networks, scan and filter hundreds of nearby access points, troubleshot the competing access points and clogged Wi-Fi channels, and more.

You can:

Inspect your Wi-Fi and surrounding networks

Scan and filter hundreds of nearby access points

Troubleshoot the competing access points and clogged Wi-Fi channels

Highlight access points for areas with high Wi-Fi concentration

Track the strength of received signals in dBm over time

Sort results by MAC Address, SSID, Channel, RSSI, Time Last Seen

Export Wi-Fi and GPS data to a KML file in Google Earth

Technical:

Uses your current wireless card and connection software

Works with Windows XP, Vista, and 7 (32 and 64 bit)

Compatible with most GPS devices (NMEA v2.3 +)

Similar:

How to Improve Your Wireless Network Performance

How to Check Wi-Fi Security Settings in Windows

How to Change Preferred Band (2.4 GHz or 5 GHz) for Wireless Network Adapters

5GHz Wi-Fi Not Showing up in Windows

Version History for inSSIDer:
https://support.metageek.com/hc/en-us/articles/204144320-inSSIDer-4-Release-Notes

Limitations:
Free MetaGeek account required.