So whilst looking at the webpage for OWL Sector I realised the 3D pie chart represents the number of people with a given transmission (brilliance, glory, etc.) and how many have two or more of them (where the segments 'bleed' into each other).
What's more, I noticed that brilliance, splendour and magnificence have the most amount of guardians infected, and correspondingly have the most logs (the dialogue) unlocked (brilliance having the most infected guardians and logs unlocked).
So based on this correlation, I hypothesis that as more guardians get infected with a given Transmission, the more of the logs for that transmission are unlocked.
Link to the webpage:
https://owlsector.bungie.net/#en
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I think you're close on this, but the number of transmissions is no longer increasing in sync with the number of infected guardians. More likely it's just updated randomly over time. They'll probably drag it out through monday before Rise of Iron launches.