A remote pickup unit or RPU is a radio system using special radio frequencies set aside for electronic news-gathering (ENG) and remote broadcasting.
An RPU is used to send program material from a remote location to the broadcast station or network.
Usually these systems use specialized high audio fidelity radio equipment.
[1] Today much of the remote broadcast use digital audio system fed over ISDN telephone lines.
This method is favored because of reliability of telephone lines versus a radio link back to the station.