Yea, I wondered about where exactly and low long to hold the TX pins high. I'm gonna play with it a little more tonight when I get home from work. Also about the mode filter, you're right that it doesn't improve the accuracy of the sensors at all, but it does do a pretty good job of getting rid of the random readings that I get that are way off. I'm also adding more code to this for my robot. For me, I add one sensor at a time. It's easier to debug. I'm adding a couple PIR sensors and a push button to turn the robot on and to turn it in standby mode.