This hint basically does the same job as AP Grapher, but can be run from the command line or over SSH — so I was able to have someone else carry my MacBook Pro around the shed while I stayed near the wireless router and fiddled with its antennas. I ssh’d into my MacBook Pro from a computer at the router, and ran the following command in Terminal:
while x=1; do /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -I | grep CtlRSSI; sleep 0.5; done
This periodically displays the received signal strength indicator (RSSI), basically the power of the microwave radio signal from your router.
The value is in dBm, which is a logarithmic scale so that an increase of 10 units means a factor of 10 increase in power; an increase of 20 means a factor of 100 increase in power; etc. Watching this reading, I was able to position the router and antenna for maximum signal strength at various places in the shed.
The airport -I command alone displays other useful information about your airport connection, like the network name, channel, authorization mode, and the noise on the microwave signal.