RF modulators convert video to RF (radio frequency) so the video can be transmitted to a television via its RF input. QAM is the RF modulation format used for cable in the U.S. This modulation format is designated by the ITU organization. Our TVB598 QAM modulator PCIe card transmits real time video or stored video from the server hard drive and sends it to multiple HD monitors simultaneously, using RF as a carrier. The TVB598 QAM can connect via an antenna or coaxial cable and features RF output.