Ah yes you're right. I didn't think that far ahead. I only have one PIR sensor and planning a location for it. But as you said, we also need to know the incoming speed. So this would require two PIR sensors, strategically placed at a known separation distance. And a few lines of BASIC script to calculate the speed and provide an estimated time of arrival, sent to the earphones in CW. Then we'll know how much time we have, to hide. BASIC scripting will be a great facilitator, for many things.?