Roomba Charging

"Mark" wrote in news:0jX4d.219$ snipped-for-privacy@newsread2.news.atl.earthlink.net:

Hello There - I've only had my Roomba Discovery for about 10 days but so far I am pleased. It's managed to charge itself and I really haven't had any problems. I don't know how it finds its charger, I'm afraid, but am happy it does. I do know that it finds dirt through sound. It listens to the particles hitting it while it vacuums. Lots of noise means keep vacuuming, little to no noise means that area is clean. I thought that was pretty ingenious.