 Since the camera's scan rate was much lower than the approximately 30 fps for NTSC video, the television standard used in North America at the time, a real-time scan conversion was needed to be able to show its images on a regular TV set.NASA selected a scan converter manufactured by RCA to convert the black-and-white SSTV signals from the Apollo 7, 8, 9 and 11 missions.When the Apollo TV camera radioed its images, the ground stations received its raw unconverted SSTV signal and split it into two branches.