This star, called Amat, is a G0V yellow star on the main sequence. Amat I is a small rocky body with no notable atmosphere, tidally locked to the star but still showing signs of a molten core. Amat-II bears life and a planetary civilization along with a large rocky moon, with many radio transmissions, as well as a few signs of space industry. Amat III is a rocky body that is very rich in metals and has three small moons. Amat IV is a large iceball. Amat V is a helium-rich gas giant. There are two asteroid belts, one between Amat II and Amat III, and a thinner one between Amat IV and Amat V. Planets VI-VIII are also largely iceballs without much to distinguish them. There are dozens of 20m-50m size craft in the system, mostly in angled and elliptical solar orbits, and Amat-II space is fairly busy with traffic.
As a brief summary of the radio traffic from Amat II, there is:
A standardized set of position and velocity transponders, with each artificial orbiting body loudly reporting its own status every once in a while.
Encoded sound transmissions representing orbital traffic control instructions, calls, and responses, mostly using standardized phrases and measurements and mostly agreeing with the automatic transponder codes.
A large quantity of encrypted digital traffic, and a much smaller quantity of plaintext digital traffic as the backbone infrastructure of the ExoNet ticks along, pushing out all manner of automatic updates and public news tickers.
Encoded sound transmissions representing public radio from the surface. A lot of weather reports, music, talk shows and poetry readings, news outlets, maritime and air traffic, and readings of daily level-3, level-4, level-5, and global economic reports and council minutes, transmitted in the clear and verifiable to anyone who asks as a matter of law.