Virtual channel

rdf:langString Virtual channel

rdf:langString In most telecommunications organizations, a virtual channel is a method of remapping the program number as used in H.222 Program Association Tables and Program Mapping Tables to a channel number that can be entered via digits on a receiver's remote control. Often, "virtual channels" are implemented in digital television, helping users to find a desired channel easily, or easing the transition from analogue to digital broadcasting in general. The practice of assigning virtual channels is most common in those parts of the world where TV stations were colloquially named after the RF channel they were transmitting on ("Channel 6 Springfield"), as it was common in North America during the analogue TV era. In other parts of the world, such as Europe, virtual channels are rarely used or needed, as TV stations there identify themselves by name, not by RF channel or callsign. A "virtual channel" was first used for DigiCipher 2 in North America. It was later used and referred to as a logical channel number (LCN) for private European Digital Video Broadcasting extensions widely used by the NDS Group and by in other markets. Pay television operators were the first to use either of these systems as a method of channel reassignment or rearrangement that suited their need to group multiple channels by their content or origin as well as to a lesser extent to localize advertising to a particular market. Free-to-air stations using Advanced Television Systems Committee standards (ATSC) used the same television frequency channel allocation that the NTSC channel was using when both were simulcasting. They achieved this using the DigiCipher 2 method. Viewers could then use the same number to bring up either service. Free-to-air DVB network operators such as DTV Services Ltd. (d.b.a. Freeview) and Freeview New Zealand Ltd. use the NorDig method and follow the same practice as pay TV operators. The exception is Freeview Australia Ltd., which also use the NorDig method and partially follow the ATSC practice of using the same VHF radio frequency channel allocation that the PAL channel is simulcasting on from the metropolitan station's main transmission point (i2, 7, 9 and 10) with the major and minor format emulated by multiplying by ten.