A standard for digital television (DTV) that supports display formats that are relatively consistent with legacy analog TV formats with respect to resolution and other specifics. SDTV also is distinguished from high definition television (HDTV). Specifically, SDTV specifies two formats, as detailed in Table S-1. * fps = frames per second ** i = interlaced, p= progressive DTV in 4:3 aspect ratio has the same appearance as analog TV based on National Television Standards Committee (NTSC), Phase Alternate Line (PAL), and Séquential Couleur Avec Mémoire (SECAM) standards, but without the ghosting, snowy images, and generally poor audio quality. Issues of signal quality in DTV transmission manifest in artifacts such as blocking, or tiling, and stuttering. The ATSC standard specifies MPEG-2 compression, and the transport subsystem as ISO/IEC 13818. Packet transport involves a serial data stream of packets of 188 octets, 1 octet of which is a synchronization byte and 187 octets of which are payload.This packet approach is suitable for ATM switching, as each 188-octet MPEG-2 packet maps into the payload of 4 ATM cells, with only 4 octets of padding required. SDTV employs ReedSolomon forward error correction (FEC) and 8-level vestigial sideband (8 VSB) RF modulation to support a bit rate of 19.28 Mbps over a 6 MHz terrestrial broadcast channel. Audio compression is based on the AC-3 specification from Dolby Digital and the ATSC. SDTV standards were developed by the Grand Alliance and reviewed, tested, and documented by the Advanced Television Systems Committee (ATSC) at the request of the United States Federal Communications Commission (FCC). See also 8-VSB, AC-3, analog, artifact, aspect ratio, ATM, ATSC, broadcast, byte, channel, compression, digital, DTV, FCC, FEC, fps, ghosting, Grand Alliance, HDTV, interlaced scanning, modulation, MPEG-2, NTSC, octet, packet, padding, PAL, payload, pixel, progressive scanning, Reed-Solomon, refresh rate, resolution, RF, scanning, SECAM, and synchronize.