DIGITAL TERRESTRIAL TELEVISION

BROADCASTING

This process produces much clearer picture and sound

quality than analog systems, similar to the difference between a compact disc recording (using digital

technology) and an audiotape or long-playing record.

A device that receives, decodes, and displays

digital video broadcasts (in both high-definition and standard-definition formats) for consumer

viewing.

Digital television uses technology that records, transmits, and decodes a

signal in digital form—that is, as a series of ones and

zeros.

It also permits additional features to be embedded

in signals including program and consumer information as well as

interactivities.

Digital Television

Primary Advantages consistent service

quality with improved immunity from noise and near-error-free, perfect picture and sound propagation within the range of performance

Primary Advantageslower operating costs through the use of

compression technology and improved system reliability

Primary Advantagesincreased

programme diversity, the ability to provide multiple services in an existing single broadcasting service channel

The main problem is resolution. The resolution of the TV controls the

crispness and detail in the picture you see. The resolution is determined by the number

of pixels on the screen.

Main Problem with Analog TV

Analog Digital

An analog TV has a 4:3 aspect ratio, meaning that the screen is 4 units wide and 3 units high. For example, a "25-inch diagonal" analog TV is 15 inches high and 20 inches wide.

The HD format for digital TV has a 16:9 aspect ratio, as shown below:

Aspect Ratio

Each broadcaster has one digital TV channel, but one channel can carry multiple sub-channels if the broadcaster chooses that option

On its digital channel, each broadcaster sends a 19.39-megabit-per-second (Mbps) stream of digital data. Broadcasters have the ability to use this stream in several different ways.

A broadcaster can send a single program at 19.39 Mbps.

A broadcaster can divide the channel into several different streams (perhaps four streams of 4.85 Mbps each). These streams are called sub-channels, and this type of broadcasting is called multicasting.

Multicasting

There are three types of broadcast digital television (DTV), each with progressively better

picture and sound quality:

Digital technology is being developed

that will offer sharper pictures on wider screens, and HDTV with cinema-

quality images. High-Definition TV

(HDTV)

Standard-Definition TV (SDTV)

Enhanced-Definition TV (EDTV)

Types of Digital Television

480i 480 lines by 704 pixels

wide, displayed in interlaced format.

Committee established by the FCC to define new standards for publicly regulated broadcast television in

the United States

Advanced Television Systems Committee (ATSC)

It has a 4:3 or 16:9 aspect ratio, 29.97-Hz frame rate, as defined by the ATSC standard.

Standard Definition Television

High-definition television (HDTV) image that is 480

vertical lines by 704 horizontal pixels displayed in

progressive format

480p

It has a 4:3 or 16:9 aspect ratio, 59.94 Hz, 29.97 Hz, and

23.98 Hz frame rates, as defined by the ATSC standard

Enhanced Definition Television

High-definition video formats that have 16:9 aspect ratio. Generally refers to 1080i or 720p images.

1,080 vertical lines by 1,920

horizontal pixels wide, displayed in

an interlaced format.

It has a 16:9 aspect ratio,

29.97 Hz frame rate,

1080i 720 vertical lines by 1,280 horizontal

pixels wide, displayed in

progressive format.

It has a 16:9 aspect ratio, 59.94 Hz, 29.97 Hz, and

23.98 Hz frame rates,

720p

High Definition Television

To compress the image for transmission, broadcasters use MPEG-2 compression

MPEG-2 allows you to pick both the screen size and bit rate when encoding the show. A broadcaster can choose a variety of bit rates within any of the suggested resolutions.

If a station wants to broadcast a sporting event (where there is lots of movement in the scene) at 1080i, the entire 19.39 megabits per second is needed to get a high-quality image.

On the other hand, a newscast showing a newscaster's head can use a much lower bit rate. A broadcaster might transmit the newscast at 480p resolution and a 3-Mbps bit rate, leaving 16.39 Mbps of space for other sub-channels.

Digital Compression

ATSC – Advanced Television Systems Committee

DVB-T – Digital Video Broadcasting - Terrestrial

ISDB-T - Integrated Services Digital Broadcasting - Terrestrial

DTV Systems

ATSC is a set of standards developed by the Advanced Television Systems Committee for digital television transmission that replaced much of the analog NTSC television system

on June 12, 2009 in the United States and will replace NTSC by August 31, 2011 in Canada

and December 31, 2021 in Mexico.

The ATSC System

The ATSC System

Featureswide screen 16:9 images up to 1920×1080

pixels in size supports a number of different display

resolutions, aspect ratios, and frame rates different resolutions can operate in progressive

scan or interlaced mode "theater quality" audio depends on numerous interwoven standards

Audio5.1 Audio Format

DVB-T is an abbreviation for Digital Video Broadcasting — Terrestrial; it is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first broadcast in the UK in 1997.

This system transmits compressed digital audio, video and other data in an MPEG transport stream.

DVB-T

The DVB-TFeatures

designed with built-in flexibility permits service flexibility robust against interference from delayed

signals DVB-T compliant signals can also be carried

over cables it can accommodate a large range of carrier to

noise ratio and channel behavior

Audio3/2 Stereo Format

Integrated Services Digital Broadcasting (ISDB) is a Japanese standard for digital television (DTV) and digital radio used by the country's radio and television stations. ISDB replaced the previously used MUSE "Hi-vision" analogue HDTV system.

ISDB-T(terrestrial) has adopted the MPEG-2 video and audio compression system.

ISDB-T

ISDB-T uses UHF 470 MHz-770 MHz, bandwidth of 300 MHz, allocate 50 channels, namely ch.13-ch.62, each channel is 6 MHz width 　 (actually 5.572 MHz effective bandwidth and 430 kHz guard band between channels).

ISDB-T allows to switch to two or three SDTV channels instead of one HDTV channel (multiplexing SDTV channels). Each channel is further divided into 13 segments. 1seg uses only single segment, and the remainder can be allocated as (1) one 12-segments HDTV program, (2) three 4-segments SDTV programs, or (3) one 8-segments (Medium Definition) program and one 4-segments SDTV program, broadcasted from a single TV station as the multiple-program arrangement

ISDB-T

Digital-ready sets - They should be identified as standard definition (SDTV) sets. These TVs are normally 480p displays with a digital tuner built in. The problem with these sets is that their maximum resolution is the low 480p SD resolution, so if you want to watch high-definition TV, you won't be able to use these sets.

HDTV-ready sets - These sets are essentially monitors able to display 1080i/p resolution in the 16:9 aspect ratio. They may or may not have tuners built in.

Integrated HDTV sets - These sets have a digital tuner for broadcast DTV signals integrated into an HDTV display. With the standards changing so much, you may end up paying for an integrated tuner that becomes obsolete.

Buying A Digital TV Set

The preferred way to handle HDTV is to purchase the components separately: A 16:9 HDTV display capable of 720p and 1080i/p

resolution A digital receiver An antenna

Since the HDTV display will be the most expensive piece and will likely last 10 years or more, buying the components in this way allows you to change the receiver if you need to. There are currently three types of receivers: You can purchase a set-top box and a Yagi antenna to receive broadcast HDTV signals.

Buying A Digital TV Set

You can purchase a set-top box and a small satellite dish to receive HDTV signals from a satellite. 

You can purchase a board for your computer that lets you use your hard disk as an HDTV storage device, along with a Yagi antenna, and use it to receive signals on both your computer monitor and your HDTV display.

Buying A Digital TV Set

A set-top box (STB) or set-top unit (STU) is a device that connects to a television and an external source of signal, turning the signal into content which is then displayed on the television screen.

Special digital set-top boxes are available for receiving digital television broadcasts on TV sets that do not have a built in digital tuner

Set-top Box

Many flat panel TVs use liquid-crystal display (LCD) screens that make use of a special substance that changes properties when a

small electric current is applied to it.

LCD technology has already been used extensively in laptop

computers.

LCD television screens are flat, use very little electricity, and work well for small, portable television sets.

Flat Panel Television

Flat panel TVs made from gas-plasma displays can be much

larger.

In gas-plasma displays, a small electric current stimulates an inert gas sandwiched between

glass panels, including one coated with phosphors that emit

light in various colors.

While just 8 cm (3 in) thick, plasma screens can be more

than 150 cm (60 in) diagonally.

Flat Panel Television

Digital television transition in the Philippines started its planning stage in 2006 after the National Telecommunications Commission (NTC) have released a memorandum on what DTV broadcast standard to be used for the country

The commission has decided to have UHF TV channels 14-51 at frequency spectrum 470-698 megahertz (Mhz) given over to digital broadcast.

DTV in the Philippines

DTV switchoverDigital Pay-TVHigh Definition Broadcast

DTV in the Philippines

ABS-CBN has applied for the digital television-terrestrial service (DTT) license to NTC , that will switch off its analog broadcast channel (Channel 2 Manila) as early as 2010. ABS-CBN is currently experimenting the transmission of digital signals on Channel 51.

ABC 5 expressed their intention of switching their current analog television broadcast set-up . They are set to test digital TV broadcast DVB-H on Channel 47.

DTV switchover

GMA Network also plans to test DVB-H in Manila as demand for content on mobile phones increases. Their application to convert their UHF station for digital broadcast service is still pending for approval from NTC.

The NTC initially decided the Philippines will use and adopt European standard DVB-T for terrestrial transmissions.

After the shutdown of analog television (which is scheduled in December 31, 2015), the European standard for digital will replace the current standard for analog television, NTSC.

DTV switchover

In November 2007, the NTC announced that it will consider other standards for replacing DVB-T.

ISDB-T was already testing by government owned TV stations and GEM-TV 49 of Iglesia ni Cristo.

Networks and organizations in favor of the DVB-T standard are ABS-CBN, GMA Network, TV5 and the Kapisanan ng mga Broadkaster ng Pilipinas. On the other hand, networks run by the government (NBN, RPN and IBC) and owned by the Iglesia ni Cristo (Gem TV) are in favor of the Japanese-based ISDB-T.

DTV switchover

Currently, several cable and satellite operators already operate on a digital platform. Digital TV is received via the use of a set-top box which is plugged into an existing analog television set and a viewing card is inserted into the box.

Advantages include an electronic program guide, parental controls that will allow parents to block inappropriate programs for kids and games.

SkyCable already offers digital cable with the use of its DigiBox.

A PLDT subsidiary has launched Cignal Digital TV which currently has 20 channels in standard definition with the use of a satellite dish.

Digital Pay-TV

Currently, high definition (HD) sets sold in the Philippine market do not have a built-in digital TV tuner to receive full HD programs via terrestrial.

Hence, connection to external equipment via an HDMI lead as well as an appropriate cable/satellite subscription package is required to receive HD programs as they are being broadcast.

High Definition Broadcast

The first locally produced television program in high definition was the opening ceremonies of the 72nd season of the UAAP.

Studio 23, a sister television network of ABS-CBN and the broadcast partner of the collegiate league, however aired the ceremonies on standard definition since the NTC has yet to decide on what DTV standard to be used for over-the-air broadcasts.

The HD broadcast of the opening ceremonies became available only cable via SkyCable.

High Definition Broadcast