During the JMP Day in Portland, OR on 12Sep2019 there were a number of questions about joining two data tables based on time values that are at different resolutions.
For example, one data table has rows on five minute intervals and the other has values at every 5 seconds.
Versions of this question have been asked a number of times in the Discussions forum.
Here are some of the threads to give you some ideas about how to approach this.
Merge data by time stamp
Join Question: timestamp range, kinda sorta?
Full Outer Join of Two Tables by Timestamp within 5 Minutes of Each Other
Joining tables with different levels of precision
