Hi I am looking to write a calculation that will find the minimum 15 minute average concentration over a specified 12-hour period (every 06:00:00 -12 hours)

Hi I am looking to write a calculation that will find the lowest/minimum 15-minute average concentration over a 12-hour period (back from 06:00:00). I only have PI ProcessBook, not PI Vision.

I know how to find the minimum single data point over 12 hours: tagmin('tag','*','*-12h*), set to 12h interval refreshing at 06:00:00, but I want to find the lowest 15 minute average within that period.

Is there a calculation that can segment the last 12 hours from a specified time into 15 minute average intervals, then an added calculation to that to find the lowest one? Thank you!