A measurement based on properties of time, like minutes of a radio conversation, is identified as

A measurement based on properties of time, such as minutes of a radio conversation, is a temporal unit.

In content analysis such time based units record how much airtime or duration a theme occupies.

Timeframe names a span within which something happens, not a unit of measurement of content.

Timeline unit is not a recognised term in content analysis.

Durational unit sounds similar but is not the accepted label for a time based recording unit.

Space and time units together let content analysts quantify coverage in print and broadcast media.