A High Definition Advanced Television Systems Committee (HD ATSC) modulator is a device used to modulate digital signals for transmission in accordance with the ATSC standards. The ATSC standards are a set of standards for digital television transmission over terrestrial, cable, and satellite networks.

The HD ATSC modulator takes an uncompressed high-definition video and audio signal and modulates it into a digital format that is compatible with ATSC standards. This modulation process is necessary for the transmission of digital TV signals over the air.
ATSC modulators are commonly used in broadcasting and other applications where high-quality digital television signals need to be transmitted. They play a crucial role in the transition from analog to digital broadcasting, providing improved picture and sound quality.
