RCA was given the contract to manufacture such a camera. It was understood at the time that motion fidelity from such a slow-scan television system (SSTV) would be less than standard commercial television systems, but deemed sufficient considering that astronauts would not be moving quickly in orbit, or even on the Lunar surface. Video signal processing 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. One signal branch was sent unprocessed to a fourteen-track analog data tape recorder where it was recorded onto fourteen-inch diameter reels of one-inch-wide analog magnetic data tapes at per second. The other raw SSTV signal branch was sent to the RCA scan converter where it would be processed into an NTSC broadcast television signal. The conversion process started when the signal was sent to the RCA converter's high-quality 10-inch video monitor where a conventional RCA TK-22 television camera – using the NTSC broadcast standard of 525 scanned lines interlaced at 30 fps – merely re-photographed its screen. The monitor had persistent phosphors, that acted as a primitive framebuffer. An analog disk recorder, based on the Ampex HS-100 model, was used to record the first field from the camera. It then fed that field, and an appropriately time-delayed copy of the first field, to the NTSC field interlace switch (encoder). The combined original and copied fields created the first full 525-line interlaced frame and the signal was then sent to Houston. It repeated this sequence five more times, until the system imaged the next SSTV frame. It then repeated the whole process with each new frame downloaded from space in real time. In this way, the chain produced the extra 20 frames per second needed to produce flicker-free images to the world's television broadcasters. This live conversion was crude compared to early 21st-century electronic digital conversion techniques. Image degradation was unavoidable with this system as the monitor and camera's optical limitations significantly lowered the original