Dear Mike,

You are 100% correct in defining my problem in your first paragraph. In fact better than I managed to put it across.

In your second paragraph you said :
"I would exapand the 2nd column by turning the table inside out so that the an upper portion of the sensor reading can be a direct index into the lookup table"

I am not clear - particularly the stuff about inside out. Could you please eloborate on it ?

Thanks

Raghu