In most telecommunications organizations, the virtual channel is the method of reprinting the program number as used in the Program Association H.222 Table and the Program Mapping Table to the channel number that can be entered via digits on remote control receiver.
A "virtual channel" was first used for DigiCipher 2 in North America and then used and referred to as the logical channel number (LCN) for the European Private Digital Video Broadcast extension widely used by the NDS and NorDig Groups in the market other.
Pay TV operators are the first to use either of these systems as a channel reassignment or rearrangement method that suits their need to group multiple channels based on their content or origin and to a lesser extent to localize ads to specific markets.
The free-to-air ATSC uses the DigiCipher 2 method to maintain the same frequency channel television allocation that the NTSC channel uses when both are simulcasting so that the same number can bring up the service.
Free-to-air DVB network operators like DTV Services Ltd. (d.b.a. Freeview) and Freeview New Zealand Ltd. using the NorDig method and following the same practice as a paid TV operator. The exception is Freeview Australia Ltd., which also uses the NorDig method and partially follows ATSC practices using the same allocation of VHF radio frequency channels that the PAL channel simulcasts from the metropolitan station's main transmission points (i2,7,9 and 10) in large and small formats imitated by multiplying by ten.
Video Virtual channel
Implementation
The DigiCipher 2 method uses a privately defined virtual channel (VCT) table to set the main and minor numbers of channels that appear on the screen separated by decimal points. The primary number for ATSC represents the original analog or non-simulcast channel frequency while the minor is the number assigned sequentially for the selected channel with zero provided for the analog channel. Channels can also be marked as hidden from viewers.
The DVB extension uses a personally defined descriptor within the Table Bouquet Association for DVB-S or Network Information Table for DVB-T. The NorDig version allows to mark channels as hidden, while the NDS Group version simply ignores channel entries.
The DVB system does not promote or mention the system either because of the simple fact that it has been defined H.222 Program Number and Transport Stream ID can achieve the same goal and also hide the channel just by removing it from table Program Association.
All of these methods have the same principle of not allowing the rearrangement of any viewer as can be achieved under analog and generic digital systems. This locked booking is one of the main criticisms using one of the methods.
Maps Virtual channel
Channel of some digital television
Because DTV can carry multiple streams called multiplexing, program numbers can be used to group them into more than one channel which can then be reassigned by virtual or logical channel numbers.
North America
Examples of major and minor ATSC numbers used for stations in the United States or Canada are typically the main program aired on channel 8 ("main channel") with analogue on 8.0 and digital in 8.1 (the first two "minor channels") with channels other entertainment is under 8.99 on channels 8.2, 8.3, and higher and each additional data channel from 8,100 to 8,999. Channels can also be displayed using hyphens (like 8-1) or spaces; however, in the general seven segment view, the decimal point will not waste the entire character. Decimal points are more familiar to FM radio listeners who listen to frequencies than channels, and avoid confusion with value ranges (for example, 2-4 can be misconstrued as ranges 2 to 4 instead of channel four sub-channels 2).
Most stations in the United States follow the ATSC numbering guidelines; however, there are some exceptions to low-power stations such as WNYZ-LP New York City, which are broadcasted on VHF 6 channels in digital, but use virtual channels 1.1 instead of 6. This operation lasted for approximately one year early in November 2008, after which WNYZ-LP returns to a low-power analog.
The assignment of virtual channels in the United States is determined in streams via a terrestrial or cable version of the Virtual Channel Table as outlined by the ATSC document "A/65", Appendix B. The rules for assigning main channel numbers are as follows:
- Existing analog stations are assigned a main channel number matching their existing analogue number
- A new digital station assigned to a channel whose main channel number is not used must use that number
- A new digital station assigned to a channel whose main channel number is suitable for use (by a former analog station) must reply, using the main channel number matching the actual channel of the station in question.
These rules generally ensure that no overlap will occur, although in the case of stations where a large number of stations in adjacent markets are close to each other, it is likely that such overlap can sometimes occur (see, eg , WJLP case). Additionally, stations may apply for licenses to broadcast some of their subchannels under secondary secondary channels in the 70-99 range; these numbers are definitely not used, because 69 is the highest assigned channel before conversion to digital broadcasting. This document does not discuss the use of other main channel numbers:
- A number under 70 that was never used in NTSC (0, 1 and 37)
- The real number of stations that use virtual channels from 52 to 69 (these stations are not covered by reciprocal rules, since station numbers are not actually set above 51)
- The numbers in the range 52-69 are not used by the former analog station
Additionally, broadcasters with more than one overlapping station within the coverage area can manage all channels to use the main channel from only one station, provided different small channel numbers are used to avoid overlapping.
When the United States begins to buy back licenses in broadcast spectrum auctions by 2017, it also allows companies that have a duopoly in the market to sell one license but continue to use channel virtual channels sold on sub-channels from others.. For example, Sunbeam Television sells WLVI in an auction, but in turn is permitted to use its virtual channel 56 on WHDH, which uses 7 virtual channels for its main channel; thus, the WHDH license uses both virtual channels, 7 and 56, on the same license.
Reach for free local TV stations from 2 to 29. All other channels are based on provider's preference.
Usage examples
Order for Time Warner cable providers:
- Backed up for on-demand customer service
- The base customer channel is from 30 to 120
- Additional subscriber channels are from 121 to 199
- Informational customer channels are from 200 to 244
- The sports subscriber channel is from 245 to 279
- Movie subscriber channels are from 280 to 299
- Targeted subscribers of Latin America from 300 to 399 and 800 to 899
- Extra HD subscriber channels are from 400 to 499
- Additional movie customer channels are from 500 to 599
- Additional overseas customer channels are from 600 to 699
- Extra season via NBA/NHL/MLB customer channel from 700 to 769
- Premium adult customer channels from 770 to 799
- Additional audio customers audio channels from 900 to 999
Sequence for Comcast cable provider:
- Reserved for on-demand customer service
- The basic customer channel is from 30 to 99 and 170 to 200
- Additional customer channels are from 100 to 170 and 201 to 299
- Additional external customer channels are from 300 to 399
- Extra sports subscriber channels are from 400 to 469
- Extra Christian customer channels are from 470 to 499
- Additional movie subscriber channels are from 500 to 599
- Targeted customer channel in Latin America from 600 to 699
- Extra HD customer channels are 700 to 899
- An extra audio music subscriber only from 800 to 999
The sequence for DirecTV satellite providers:
- Reserved for DirecTV (and 201) customer information
- The local free-to-air station is from 2 to 69
- The shopping customer's channel is from 70 to 99
- Additional movie customer channels are from 100 to 200
- The basic customer channel (and extra HD) is from 202 to 389
- east NY and CA west coast FTA network subscriber channel from 390 to 400
- Targeted customer channels in Latin America from 401 to 499
- Premium customer channels from 500 to 549
- Premium adult customer channels from 550 to 599
- Extra regional sports subscriber channel from 600 to 699
- An extra NFL/NBA/NHL subscription season from 700 to 799
- Additional audio customer audio channels from 800 to 999
- Extra non-North/Latin Latin customer channels from 2000 to 2199
- The DirecTV system/interactive channels are hidden from 9000 to 9539 and 9950
- DirecTV system/hidden HD channels from 9540 to 9559
- DirecTV system/hidden instrumental channels from 9560 to 9599
Mexico
After the introduction of digital television in Mexico, most stations use virtual channels that match the position of previous analog channels, with selected radio stations as their physical channels (such as XHMNU-TDT in Monterrey, which keeps the virtual channel 53 to 35). However, Mexican television is much more centralized than in other ATSC countries, with three of the four national commercial network brands with their Mexico City channel numbers. There is also the potential that new entrants, almost universally located at UHF, will be harmed by a higher virtual channel than existing stations starting at VHF - special attention given the recent appreciation of the national television network for Grupo Imagen.
In December 2015, the Federal Telecommunications Institute opened a period of public commentary on public guidelines for virtual channel assignments, and on June 17, 2016, IFT officially released the final version of the guidelines. The plan calls for the standardization of virtual channels based on networks, not previous analog positions, with automatic assignments based on programming information on files with IFT; it also sets October 27 for a coordinated switch of all virtual channels. In early September, a full list of virtual channel tasks was released.
The plan eliminates many local variants for national and regional networks. Before standardization, Canal 5, the national network, seen on 25 different virtual channel numbers in different Mexican cities; the plan is standardized as a national 5 channel.
Overall, IFT accredits nine national television networks and grants them national rights to virtual channels. Five commercial ads: Azteca Trece (channel 1, changed from the top 13 at the request of Azteca TV); Las Estrellas (channel 2), Imagin (channel 3), Canal 5 (channel 5), and Azteca 7 (channel 7)). In addition, national public broadcasters receive channels: Canal Once (channel 11), Una Voz con Todos (channel 14, later renamed Canal Catorce), UNAM TV (channel 20), and Canal 22 (channel 22). The IFT also provides general numbers to 14 regional networks (mainly operated by state governments) and virtual channels to nearly 100 local stations across the country. Local stations are mostly assigned to channels 4, 8, 10, 12, and less common 9, as well as other numbers. Some retain existing channel numbers, especially if broadcasted on UHF in analog. Initially, channel 6 is reserved, in the event that a 2017 auction from a local TV station produces a national network (which is not the case).
The biggest exception to standardization is on the US-Mexico border, where due to a US station on the desired virtual channel and the objections of the Federal Communications Commission of the US, 11 Mexican stations are operating on a virtual channel other than expected. In Tijuana, only one Mexican station can change its virtual channel.
Australia
In Australia, the allocation of logical channel numbers is governed by the guidelines set by the commercial broadcaster association, Australian Free TV.
This is defined in terrestrial broadcast streams using the NorDig descriptor format in the DVB "Network Information Table."
LCNs in Australia may have one, two or three digits. Each LCN allocated network starts with a certain prefix - for example, all Nine metropolitan services using LCN begin with the number '9'. Generally, but not always, single digit LCNs are allocated to the primary SD service (One Network sub-channel is the main exception). LCN does not need to be adjacent, and channels can be identified by more than one LCN. For example, ABC Television's main ABC service allocates LCN 2 and 21; the latter allows to be easily accessed among other ABC services located in the 21-24 range.
Regional affiliations of three metropolitan networks are provided with different LCN prefixes. For example, channels owned by affiliates of the Nine Networks (in this case NBN Television) begin with an '8' digit rather than '9'. This allows areas that are part of the metropolitan market and regional markets, such as the Gold Coast, Sunshine Coast, and Central Coast, to receive all local commercial services. ABC and SBS use the same prefix in all areas.
Prefixes for remote-area services are intended to be overlaid on this model. When digital transmission is initiated in these areas, services licensed for Remote Central and Eastern Australia (Imparja and Southern Cross Central) licensed regions have provided "metropolitan" prefixes to their affiliates; they are in Remote Western Australia (GWN and WIN WA) prefix "regional".
A number of LCNs are provided for a variety of reasons:
- LCN 4 was originally intended for free-to-air video program guide. In practice, the LCN 4 prefix for most of its life is largely unused, except in Sydney (where used by Forty Four trial digital data service 2004-2010). Since 2010, the capital's community television stations (or "Channel 31" stations, after their distinctive analog channel positions) use LCN 44.
- The LCN range of 350-399 is intended to be allocated by the receiver to channels that duplicate stronger LCN signals, or transmitted without LCN. For example, if two LCN 2 broadcasts are found, one signal (generally stronger) will be allocated to LCN 2, and a weaker one should be allocated to, say, LCN 350.
- The LCN 450-499 range is intended for use by non-announcer test services.
Usage examples
The Freeview sequence (aka FreeTV) is determined by the broadcaster's transport:
- Ten networks of metropolitan HD channels are on channel 1
- The primary SD channel of ABC is on channel 2
- The primary SDS SDS channel is on channel 3
- VAST regional news guides
- The 9 primary regional SD channels are on channel 5
- The 7 primary regional SD channels are on channel 6
- 7 SD metropolitan SD networks are on channel 7
- Ten regional networks and 9 Northern NSW primary SD networks are on channel 8
- 9 primary primary SD metropolitan SD networks are on channel 9
- Ten primary metropolitan SD network channels exist in channel 10
- The ten other metropolitan networks of TV channels are from 11 to 19
- The ABC HD channel is on channel 20
- ABC other TV channels from 21 to 29
- The SBS HD channel is on channel 30
- The other SBS channels are from 31 to 39
- local public service is 44
- The various Government/Government channels are from 40 to 43 and 45 to 49
- 9 Network HD Channels are on channel 50
- 9 other regional TV channels are from 51 to 59
- 7 Networked regional HD channels are on channel 60
- The other 7 regional TV channels are from 61 to 69
- 7 network of metropolitan HD channels are on channel 70
- 7 other metropolitan TV channel networks are from 71 to 79
- Ten regional networks and 9 Northern NSW Networks HD are on channel 80
- Ten regional and 9 Northern NSW networks of other TV channels are from 81 to 89
- 9 network of metropolitan HD channels is on channel 90
- 9 other metropolitan TV channel networks are from 91 to 99
- Ten Networks extends other TV channels from 100 to 199
- The ABC Audio Only channel is from 200 to 219
- ABC outside the extended area/channel is from 220 to 299
- SBS outside the extended area/channel is from 300 to 349
- Each channel outside the region is from 350 to 399
- The Regional VAST news channel is from 400 to 499
- The VAST community channel is from 600 to 699
- 7 networks extend other TV channels from 700 to 799
- The VAST information channel is 800 to 899
- 9 extended network of other TV channels is 900-999
Orders for Foxtel (which are wholesalers to Austar and Optus) are mostly based on channel content:
- System Services from 1 to 99 and above 989
- Public Entertainment from 100 to 149
- Changed time from 150 to 169
- Specialists from 170 to 179
- Communities from 180 to 199
- High Definitions from 200 to 299
- Interactive/Miscellaneous from 300 to 399
- Films from 400 to 499
- Sports from 500 to 599
- News/Information from 600 to 699
- Youngsters from 700 to 799
- Music from 800 to 829
- Audio Music Only from 830 to 849
- Free to Air Audio Only from 850 to 899
- Pay Per View from 900 to 939
- Europe from 940 to 959
- Adult Pay Per View from 960 to 989
- Help on 999
Europe, Africa and Middle East
In Europe, Africa and the Middle East, there is no specific numbering system for sub-channels; two related "channels" (ie, program flow) may have completely unrelated numbers (for example, in the UK, ITV is channel 3 and its digital channel, ITV2 is channel 6 in Freeview).
In the UK and Ireland, Freeview channel numbers are defined in terrestrial broadcasting streams using the NorDig descriptor format in the DVB "Network Information Table".
Usage examples
Orders for Freeview/Sky hybrid bundling are largely based on channel content:
- Public Entertainment from 1 to 99
- High Definition from 100 to 119
- Young Children from 201 to 219
- News/Public Service from 230 to 239
- The MHEG-5 non-broadcast Internet broadcast is from 260 to 299
- Recommended for YouView from 300 - 599
- Interactive MHEG-5 from 600 to 609
- Adult Pay Per View from 670 to 695
- Only Audio from 700 to 777
- ITV3 HD at 778
- Old test and channel from 790 to 799
- D RATED Channels (on the first day) (Samsung only) 800-850
Orders for the Republic of Ireland Saorview are based on channel priority to state-owned television channels:
- Country's main TV channel
- Secondary secondary secondary RT TV channel
- other TV channels from 3 to 5
- TV channels RT â € ° a state property other than 6 to 8
- channel RTÃÆ' â € ° Audio Only state property from 200 to 209
In continental and eastern Europe, virtual channels are not used, as television sets and receivers allow users to freely assign arbitrary "program numbers" or "program letters".
The station still markets itself as a "first", "second", or "third" channel (and so on), or "channel A", "channel B" or "channel C" etc. But this reflects the number of programs on which channel which should be stored instead of the RF channel used to transmit the signal.
Virtual channels are also used on live broadcast satellites, such as Dish Network, DirecTV, and Astra. Instead of several dozen channels with several sub-channels each, this service maps up to hundreds of individual numbered channels. This also applies to digital cable and satellite radio services.
Japanese
In Japan, digital terrestrial TV broadcasters in each region are allocated "remote control ID" (or, "Remocon lock ID"), which currently amounts from 1 to 12. Remote control ID allocations for broadcasters outside Kanto generally follow Tokyo they are network-based flagships; However, stations in some areas deviate from this. Current technical standards allow for expansion to a maximum of 16 broadcasters per region.
Each underlying channel is then assigned a three-digit number, which is based on a specified remote control ID, followed by a sub-channel number. For example, NHK Educational TV is designated as remote control ID 2 (national). Their main channel is therefore assigned virtual channel 021. If multichannels broadcaster (which ISDB-T standard allows up to three standard definition streams), additional streams will be assigned virtual channels 022 and 023, respectively. The current standard allows a maximum of eight virtual channels per broadcaster (in this example 021-028).
Additional data services use virtual channels within the range of 200-799 - in this example, the network can use the 22x, 42x, and 62x ranges.
New Zealand
The allocation of logical channel numbers is regulated by Freeview and incorporated into the transport flow with most Kordia maintaining equipment coded by TVNZ which also codes for all other non-critical DVB metadata such as EPG and channel naming.
SKY Network Television also determines the numbering of their own channels that use similar NDS encoding formats. They distribute their channels to the only other NZ pay-TV operators, Vodafone, and to short-lived Telecom First Media.
The Freeview LCNs are encoded in a terrestrial broadcast stream using the NorDig descriptor format in the DVB "Network Information Table." And in two streams of satellite broadcasts also use the format Descriptor NorDig, but instead in the DVB "Table Association Bouquet." BAT is used on satellites so that the region-orientation channel can be performed on the receiver certified (that is, the ordering channel is locked).
Usage examples
The Freeview order is based on how the channel pays for broadcast services:
- high national audience TV channels under 20
- lower national TV viewer channels are from 20 to 29
- TV channels entered locally are from 30 to 40
- Local non-Kordian operators are from 41 to 49
- priority national audio only channels from 50 to 69
- priority national priority audio channel from 70 to 79
- TVNZ Provided MHEG-5 Interactive (not currently in use) is 80 to 99
- The Broadcast Test Channel (no longer used) is from 100 to 199
- TVNZ Provides non-broadcast MHEG-5 Internet streams from 200 to 299
- System Services provided by TVNZ (not currently in use) from 300 to 399
- TVNZ Providing the MHEG-5 interactive information channel is from 500 to 599
- TVNZ Provides Interactive MHEG-5 testing channels from 600 to 699
- TVNZ Rendered by Receiver Download is 700 to 799
The order for Sky is mostly based on channel content:
- Public Entertainment is under thirty (before April 2013 under twenty)
- Movies from 30 to 39 (before April 2013 are 20 to 29)
- Sports from 50 to 69 and 333 (before April 2013 are 30 to 39 and 333)
- Pre-Teen from 100 to 109 (before April 2013 is 40 to 49)
- Information from 70 to 79
- Public Services from 80 to 84 (before April 2013 is from 85 to 89)
- News from 85 to 99 (before April 2013 is from 90 to 99)
- Music from 110 to 119 (before April 2013 is 60 to 69)
- Pay-Per View Movies from 120 to 139 (before April 2013 are 200 to 219)
- Adult Pay-Per View from 140 to 139 (before April 2013 is 200 to 219)
- Religious/Country Funding from 200 to 299 (before April 2013 is 110 to 119)
- Asian language from 300 to 309
- Asian Audio Only from 311 to 314
- Eastern Non-Asian languages ​​from 315 to 319
- Music Audio Only from 400 to 419
- Free to Air Audio Only from 420 to 429 (before April 2013 is 500 to 599)
- Capture time from 500 to 599 (before April 2013 is 80 to 84)
- System Services from 800 to 999
- Interactive/Miscellaneous (before April 2013 is 50 to 59)
- Europe (before April 2013 is 100 to 109)
The sequence for Skyview/TVNZ/Kordia Freeview bundling called Igloo is as follows:
- The national Freeview Primary channel from 1 to 5
- Sky Pay TV Channels start from 6 to 19
- National Freeview secondary channels from 30 to 39
- Freeview-related sports channels from 40 to 44
- Infomercial Freeview Channel from 45 to 49
- News related to Freeview channels from 50 to 54
- Religious Freeview Channel from 55 to 59
- Freeview channel of secondary languages ​​from 60 to 64
- non-English Freeview channel from 65 to 69
- a localized English Freeview channel from 80 to 89
- Local non-Freeview channel from 100 to 109
- Freeview's custom audio channel from 110 to 119
Philippines
When the Philippines began its transition to digital terrestrial television in 2008, virtual channels have been temporarily assigned to the currently operating TV networks. In June 2010, the National Telecommunications Commission finally adopted ISDB-T as the only terrestrial digital television standard in the country.
LCNs used in ISDB-T in the Philippines have been previously assigned to networks currently operating on digital TV. HD GEM Small-player on DZCE-TV is the first Philippine TV network to use ISDB-T, assigned to LCN 2.11 using an analog channel 49. The Government-owned People's Television Network or PTV is assigned to 1.1 using its analog channel 48 because of its government-owned status. High definition channels are given decimal with "11", while multi-SD channels use decimal with "1, 2, 3... and so on" as their sub-channels.
In the first quarter of 2011, NTC assembled to form a TWG-IRR that will draft implementing regulations and regulations on digital TV. In addition, it will include frequency planning for upcoming digital TV networks.
Digital radio
Digital radio also uses channels and sub-channels in DAB format. iBiquity's HD Radio uses HD1, HD2,..., HD7 channels. HD1-3 is available in FM hybrid mode, while seven HD channels are available in pure digital mode.
The IBOC (Digital Radio Mondiale) station currently does not use virtual channels due to the limited bandwidth available in analog sidebands.
References
External links
- Technical specification of Logical Channel Number
Source of the article : Wikipedia
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