Referring to television in digital, rather than analog, form. As is the case with digital communications, in general, DTV offers the advantages of enhanced bandwidth efficiency through compression, improved signal quality due to reduced noise, and enhanced overall management and control. DTV does not suffer from the ghosting, snowy images, and generally poor audio quality associated with analog TV. Issues of signal quality in DTV transmission manifest in artifacts such as blocking, or tiling, and stuttering. Digital video content benefits from enhanced processing, storage, and manipulation. 1 2 3 A 4 5 6 B 7 8 9 C * 0 # D Hz 1209 1336 1477 1633 697 770 852 941 More specifically, digital content advantages include editing, alteration (e.g., morphing), reproduction, compression, and store-and-forward capability. DTV standards include high definition television (HDTV) and standard definition television (SDTV). The ATSC standards specify MPEG-2 compression, and the transport subsystem as ISO/IEC 13818. Packet transport involves a serial data stream of packets of 188 octets, one 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 four ATM cells, with only 4 octets of padding required. SDTV employs Reed-Solomon 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, ATM, ATSC, bandwidth, broadcast, byte, channel, compression, digital, DTV, FCC, FEC, ghosting, Grand Alliance, HDTV, modulation, MPEG-2, NTSC, octet, packet, padding, PAL, payload, Reed-Solomon, RF, SDTV, SECAM, signal, store and forward, synchronize, TV, and video.