“The world is moving towards High Definition Television [HDTV]” “Don’t buy a regular TV now, they are going to be better in every way when HDTV comes into market”. Some of the many phrases dropped by people who are loosely following the HDTV effort. When asked, “How do you know?”, these people confidently responded with, “Because technology is just going to get better and better.” Though HDTV is revolutionizing the world, and the technology is getting better, very little thought is put into the effort done by engineers in the leading companies. People expect television to constantly improve, but these improvements do not occur on their own. Rather, they arise from many different factors, such as nationalistic politicians who push American companies to develop HDTV, the computer industry pushing for a digital television, or engineers inventing new ideas.
In Inventing Accuracy, Donald Mackenzie clearly describes a false perception people have regarding improvements in technology, a notion he refers to as a natural trajectory. Through a chronology of the history of nuclear missile guidance, he defines such a trajectory as "a direction of technical development that is simply natural, not created by social interests but corresponding to the inherent possibilities of the technology (pg 167). However, in the context of military guidance, he comes to the conclusion that these things can't really exist. All trajectories need to be helped along by technical, social, and political pressures. Nothing happens by itself.
Even so, people still believe technologies advance because it is natural phenomenon. Moore’s Law is a prediction that the pace of microchip technology change is such that the amount of data storage that a microchip can hold doubles every year or at least every 18 months. Intel’s 8080 in 1975 had 4500 transistors. In 1995, when Intel introduced the Pentium Pro, it had 5.5 million transistors. However it did not occur because it was on a predestined plan to do so, but rather engineers in Santa Clara working hard to compete with other companies. If no other company that creating chips existed, Intel would most likely be just as happy to fire all its engineers and sell their chips at high prices.
HDTV is no different. This paper strives to analyze HDTV as the product of technological trajectories similar to the way Mackenzie did for nuclear missile guidance. To look under the mask of the natural trajectory and present HDTV as a true product of its surroundings, a manifestation of corporate interests, technical desires, and government goals. This paper also will show that HDTV is not really the natural way of the world, but one method that has been contrived through the involvement of lots of different parties, and done so successfully enough to convince the nation that it's a natural thing that should be expected and accepted by society as a great technological advancement.
Download pdf HDTV: The Engineering History
Friday, February 27, 2009
Thursday, February 26, 2009
Digital Terrestrial Broadcasting in HDTV
The core of the digital terrestrial broadcasting, as well as satellite digital which started in December, 2000, is Hi-Vision. An HDTV image has five times more visual information than a conventional television picture, and 1,125 scanning lines in HDTV system give pictures their detailed realism. Also, a wide-screen format with a 16:9 aspect ratio provides a powerful viewing experience. HDTV also provides CD-quality sound and 5.1 surround sound broadcasting, which is capable of reproducing sounds with a realistic feeling of depth that gives listeners a heightened sense of involvement by using six-channel speaker system. NHK has delivered spectacular images from the Space Shuttle, the depth of the ocean, and the Antarctica. Almost 90% of NHK’s main channel (Digital General TV) is broadcast in HDTV.
Data broadcasting
Data broadcasting gives viewers access to information whenever they need it by simply pressing a remote control button. Viewers can request and withdraw detailed information in such emergency situations as earthquakes and severe storms, as well as program related data, local weather forecasts, and sports results. This function will enhance detailed information services.
Interactive services
Interactive functions allow viewers to actively participate in TV programs from their living room. One can join a quiz show as a competitor and join a contest as a juror by submitting the answers and opinions through the television screen. NHK’s most popular music program, “Red & White Year-end Song Festival” (to be aired on 31 December) will invite audience to screen the songs as the jurors.
Multi-channel services
Digital broadcasting has the bandwidth capacity to broadcast up to three different standard-definition programs on one single channel. For example, it is possible to air a children’s animation program, a language learning program, and a cooking program all at the same time on NHK Educational TV channel.
Download pdf Digital Terrestrial Broadcasting in HDTV
Data broadcasting
Data broadcasting gives viewers access to information whenever they need it by simply pressing a remote control button. Viewers can request and withdraw detailed information in such emergency situations as earthquakes and severe storms, as well as program related data, local weather forecasts, and sports results. This function will enhance detailed information services.
Interactive services
Interactive functions allow viewers to actively participate in TV programs from their living room. One can join a quiz show as a competitor and join a contest as a juror by submitting the answers and opinions through the television screen. NHK’s most popular music program, “Red & White Year-end Song Festival” (to be aired on 31 December) will invite audience to screen the songs as the jurors.
Multi-channel services
Digital broadcasting has the bandwidth capacity to broadcast up to three different standard-definition programs on one single channel. For example, it is possible to air a children’s animation program, a language learning program, and a cooking program all at the same time on NHK Educational TV channel.
Download pdf Digital Terrestrial Broadcasting in HDTV
Wednesday, February 25, 2009
Using FPGA-Based Channel Bonding for HDTV Over DSL
On an almost daily basis, new video or voice applications push the bandwidth requirements for DSL networks, while telecom carriers in the U.S. and worldwide are targeting delivery of digital and high-definition television (HDTV) to consumers. To achieve delivery of such services without deploying new fiber everywhere, carriers must leverage existing copper deployments already in the ground.
Most DSL lines offer enough capacity for delivering standard-definition television (SDTV). Most programs are available from streaming servers at bitrates of about 750 kbps, with some programs providing a 1.5 Mbps bitrate. However, to allow high-quality HDTV streaming and multiple channels simultaneously, a home must have a bandwidth of at least 16 Mbps. Although newer DSL generations of ADSL2 and VDSL can offer these speeds, they cannot offer high speed over a sufficiently longer distance on a typical DSL line. Therefore, HDTV programs can be delivered only to households close to the DSLAM. Those located further away can only receive lower quality SDTV programming.
To ensure that DSL remains the preferred choice for end users, service providers are looking for new ways to improve the performance of DSL networks. While VDSL and ADSL2 provide better performance, the distance limitations are difficult to overcome. Another scenario is to bring the DSLAMs closer to the end users, but the costs involved with installing new equipment in the network are often prohibitive.
Channel Bonding in DSLAMs and DSL Modems
DSL channel bonding provides the ideal mix of features: higher bandwidth to all users and the ability to extend the distance that can be reached at a certain bandwidth. Instead of using a single copper pair, DSL bonding distributes traffic over a bundle of copper pairs. To achieve an effective bandwidth of 12 Mbps, three DSL lines of 4 Mbps are bundled, with a channel bonding processor at each end of the lines. In most copper networks, subscribers are already connected via several wires, so no new cables need be installed to provide channel bonding service, as shown in Figure 1.
Download pdf Using FPGA-Based Channel Bonding for HDTV Over DSL
Most DSL lines offer enough capacity for delivering standard-definition television (SDTV). Most programs are available from streaming servers at bitrates of about 750 kbps, with some programs providing a 1.5 Mbps bitrate. However, to allow high-quality HDTV streaming and multiple channels simultaneously, a home must have a bandwidth of at least 16 Mbps. Although newer DSL generations of ADSL2 and VDSL can offer these speeds, they cannot offer high speed over a sufficiently longer distance on a typical DSL line. Therefore, HDTV programs can be delivered only to households close to the DSLAM. Those located further away can only receive lower quality SDTV programming.
To ensure that DSL remains the preferred choice for end users, service providers are looking for new ways to improve the performance of DSL networks. While VDSL and ADSL2 provide better performance, the distance limitations are difficult to overcome. Another scenario is to bring the DSLAMs closer to the end users, but the costs involved with installing new equipment in the network are often prohibitive.
Channel Bonding in DSLAMs and DSL Modems
DSL channel bonding provides the ideal mix of features: higher bandwidth to all users and the ability to extend the distance that can be reached at a certain bandwidth. Instead of using a single copper pair, DSL bonding distributes traffic over a bundle of copper pairs. To achieve an effective bandwidth of 12 Mbps, three DSL lines of 4 Mbps are bundled, with a channel bonding processor at each end of the lines. In most copper networks, subscribers are already connected via several wires, so no new cables need be installed to provide channel bonding service, as shown in Figure 1.
Download pdf Using FPGA-Based Channel Bonding for HDTV Over DSL
Tuesday, February 24, 2009
One Transistor Enables Clean HDTV and NTSC Video Sync Separation
The growing popularity and availability of HDTV is creating a small revolution in the video industry. New video systems must be capable of handling the standard NTSC (National Television System Committee) composite signal as well as high definition signals. Since low cost and low power concerns drive system designers to find the simplest solutions, this article describes a one transistor network that enables a single video sync separator to operate for both HDTV and NTSC systems.
In the sample NTSC signal shown in Figure 1, the color burst and color subcarriers are identified. A “slice level” is drawn half-way down the drop for horizontal synchronization. Variations in color burst or dark blues within the subcarrier can dip below the slice level, causing false sync pulses in addition to the 15kHz horizontal sync signal. With HD (High Definition) signals (Figure 2), the color information is carried separately, so there is no color burst or subcarrier to cause false sync pulses. However, note that the horizontal sync pulse is shorter and higher frequency (20kHz).
It is advantageous if a single sync separator will operate with both HD and NTSC signals. Since false triggers can occur with NTSC signals, a filter can be added in the sync separator path to reduce the height of the color burst and subcarrier signals. This filter cannot be included during HD detection, though, since its shorter sync pulse would also be attenuated, causing missed triggers.
The ISL59885 is a sync separator which features both HD and NTSC detection. An output, labeled HD, is provided which responds to the type of input - high for NTSC and low for HD. This external pin can be used to insert a low-pass filter into the sync separator path preventing false sync pulses in composite video. The circuit is shown in Figure 3. When composite signal (NTSC/PAL) is detected, the filter is enabled by applying a logic high to the base of the transistor. When component signal (HD) is detected, the filter is disabled by having the HD pin at a logic low state. Although the transistor is disabled during HD, a low pass filter is still present to filter out any noise present at the input.
Download pdf One Transistor Enables Clean HDTV and NTSC Video Sync Separation
In the sample NTSC signal shown in Figure 1, the color burst and color subcarriers are identified. A “slice level” is drawn half-way down the drop for horizontal synchronization. Variations in color burst or dark blues within the subcarrier can dip below the slice level, causing false sync pulses in addition to the 15kHz horizontal sync signal. With HD (High Definition) signals (Figure 2), the color information is carried separately, so there is no color burst or subcarrier to cause false sync pulses. However, note that the horizontal sync pulse is shorter and higher frequency (20kHz).
It is advantageous if a single sync separator will operate with both HD and NTSC signals. Since false triggers can occur with NTSC signals, a filter can be added in the sync separator path to reduce the height of the color burst and subcarrier signals. This filter cannot be included during HD detection, though, since its shorter sync pulse would also be attenuated, causing missed triggers.
The ISL59885 is a sync separator which features both HD and NTSC detection. An output, labeled HD, is provided which responds to the type of input - high for NTSC and low for HD. This external pin can be used to insert a low-pass filter into the sync separator path preventing false sync pulses in composite video. The circuit is shown in Figure 3. When composite signal (NTSC/PAL) is detected, the filter is enabled by applying a logic high to the base of the transistor. When component signal (HD) is detected, the filter is disabled by having the HD pin at a logic low state. Although the transistor is disabled during HD, a low pass filter is still present to filter out any noise present at the input.
Download pdf One Transistor Enables Clean HDTV and NTSC Video Sync Separation
Monday, February 23, 2009
SDTV Lens on HDTV Camera: To Be or Not to Be?
The essential distinction between SDTV and HDTV is bound up in the core issue of the term “high definition”. It implies that HDTV is distinguished from traditional video primarily by more “definition” – thus producing much higher picture sharpness. Thus, any discourse on mixing SDTV products with HDTV products needs to be closely examined from the viewpoint of its impact on the “high definition” aspect of the final imagery. Unlike the digital cameras and recorders that make up contemporary digital imaging systems, the lens is a totally analog technology. It is a very physical technology, in the fullest sense of the word. The lens is also dynamic— in terms of the substantial degree of control it can exercise over the object image that it presents to the camera image sensors.
Those variations in light level, focus, and focal range offered by the lens come with some technical penalties. As this paper is intended to examine “definition” the focus will be on the behavior of lens resolution. It is useful to establish some metrics in optical terms, for picture “definition”. Audio and video systems (such as a television camera) are described by considerations of bandwidth and the specific system responses over the frequency ranges encompassed within their respective bandwidths. A similar approach can describe the resolution performance of a lens.
OPTICAL BANDWIDTH
Lens Contrast and Resolution are inextricably intertwined. A series of closely spaced alternating black and white lines are visually distinguished by their relative contrast to each other. As their thickness and spacing are progressively reduced our human visual system is tasked to distinguish between these alternating lines. At some point we fail to do so and they blur into a gray patch. The same thing occurs as the test chart object scene passes through a lens. As the alternating lines increase in spatial frequency their optical representation by the lens will exhibit a progressive roll-off as simplistically illustrated in
Figure 1. In other words, the contrast reproduction capability of the lens is modulated as a function of the fineness of detail of the alternating black and white lines. This particular representation of the lens output is technically termed the Modulation Transfer Function – or MTF. The horizontal axis represents the spatial frequency (increasingly fine detail from left to right) in Line-pairs per millimeter (Lp/mm). The vertical axis is the contrast (amplitude of black to white) of the optical image output of the lens.
Download pdf SDTV Lens on HDTV Camera: To Be or Not to Be?
Those variations in light level, focus, and focal range offered by the lens come with some technical penalties. As this paper is intended to examine “definition” the focus will be on the behavior of lens resolution. It is useful to establish some metrics in optical terms, for picture “definition”. Audio and video systems (such as a television camera) are described by considerations of bandwidth and the specific system responses over the frequency ranges encompassed within their respective bandwidths. A similar approach can describe the resolution performance of a lens.
OPTICAL BANDWIDTH
Lens Contrast and Resolution are inextricably intertwined. A series of closely spaced alternating black and white lines are visually distinguished by their relative contrast to each other. As their thickness and spacing are progressively reduced our human visual system is tasked to distinguish between these alternating lines. At some point we fail to do so and they blur into a gray patch. The same thing occurs as the test chart object scene passes through a lens. As the alternating lines increase in spatial frequency their optical representation by the lens will exhibit a progressive roll-off as simplistically illustrated in
Figure 1. In other words, the contrast reproduction capability of the lens is modulated as a function of the fineness of detail of the alternating black and white lines. This particular representation of the lens output is technically termed the Modulation Transfer Function – or MTF. The horizontal axis represents the spatial frequency (increasingly fine detail from left to right) in Line-pairs per millimeter (Lp/mm). The vertical axis is the contrast (amplitude of black to white) of the optical image output of the lens.
Download pdf SDTV Lens on HDTV Camera: To Be or Not to Be?
Sunday, February 22, 2009
HDTV Standards and Practices for Digital Broadcasting
This eduGuide is intended for the video professional that is starting to become involved with designing, specifying, operating or maintaining digital video broadcast and distribution systems for HDTV. For over 50 years our industry has used television technology of a primarily analog nature. True, some digital technology has been used in broadcast facilities for standard definition or NTSC and PAL systems, but its deployment has been limited and ultimately converted back to an analog signal for distribution and broadcast.
Today, HDTV is the first broadcast technology designed to be exclusively digital from image capture to display on the consumer’s TV set. Many different technologies are used where the video, and audio, undergoes many transformations from start to finish. This eduGuide will help you to understand the chain of technologies used, the industry standards behind them, for both copper and fiber optic distribution, and the practices video professionals are developing for the new world of HDTV.
The Role of Technical Standards
The broadcast industry, unlike the A/V and computer industries, has historically been a proponent and practitioner of technical standards for video and audio processing and distribution. The reason is simple: interoperability. The broadcaster, and those in related professional video industries, need to be able to select the best equipment for the task at hand. Since all the equipment in a distribution or edit suite will need to process the same video and audio, there is a need to define and adhere to interface standards between the various pieces of equipment.
There are several technical standards organizations in the world that develop and promote these standards but perhaps the most noted is SMPTE. The Society of Motion Picture and Television Engineers (SMPTE) has membership and participation from individuals, broadcasters and equipment manufacturers from around the world. The expertise and experience brought to bear by this group creates a forum for developing very powerful and lasting standards.
The buyer and user of broadcast equipment is the ultimate beneficiary of this process. He can be assured that products compliant with a particular set of standards will allow video and audio signals to be communicated between them in a recognizable way without requiring additional processing or interfacing. The benefit to the user is lower design and operational costs and a wider selection of equipment to choose from for a particular application without being locked in to any one equipment manufacturer employing proprietary interfaces and protocols.
Download pdf HDTV Standards and Practices for Digital Broadcasting
Today, HDTV is the first broadcast technology designed to be exclusively digital from image capture to display on the consumer’s TV set. Many different technologies are used where the video, and audio, undergoes many transformations from start to finish. This eduGuide will help you to understand the chain of technologies used, the industry standards behind them, for both copper and fiber optic distribution, and the practices video professionals are developing for the new world of HDTV.
The Role of Technical Standards
The broadcast industry, unlike the A/V and computer industries, has historically been a proponent and practitioner of technical standards for video and audio processing and distribution. The reason is simple: interoperability. The broadcaster, and those in related professional video industries, need to be able to select the best equipment for the task at hand. Since all the equipment in a distribution or edit suite will need to process the same video and audio, there is a need to define and adhere to interface standards between the various pieces of equipment.
There are several technical standards organizations in the world that develop and promote these standards but perhaps the most noted is SMPTE. The Society of Motion Picture and Television Engineers (SMPTE) has membership and participation from individuals, broadcasters and equipment manufacturers from around the world. The expertise and experience brought to bear by this group creates a forum for developing very powerful and lasting standards.
The buyer and user of broadcast equipment is the ultimate beneficiary of this process. He can be assured that products compliant with a particular set of standards will allow video and audio signals to be communicated between them in a recognizable way without requiring additional processing or interfacing. The benefit to the user is lower design and operational costs and a wider selection of equipment to choose from for a particular application without being locked in to any one equipment manufacturer employing proprietary interfaces and protocols.
Download pdf HDTV Standards and Practices for Digital Broadcasting
Saturday, February 21, 2009
HDTV and Mobile TV: post Digital Switchover
In May 2006, we produced a discussion paper examining the future market demand and technical opportunities for digital terrestrial broadcasting. We proposed the adoption of new technologies – the MPEG4 video coding standard and a new broadcasting standard, now called DVB-T2 – that would enable the existing UHF spectrum to be used much more efficiently to carry both HDTV and mobile broadcast services alongside existing Freeview services once UK analogue TV broadcasting ends in 2012.
That paper contributed to a UK and an international dialogue that has led to the recent publication of proposals from Ofcom and the public service broadcasters to introduce terrestrial HDTV services in the UK, based on the new DVB-T2 standard. Ofcom has also indicated that it plans to auction off 14 of the UHF channels currently used for analogue broadcasting, leaving 32 channels to carry 6 digital TV multiplexes (networks).
Last autumn the authors of the original paper came together again to build on the progress made over the previous 18 months and to develop their earlier proposals taking into account the full potential for digital terrestrial broadcasting in the UK. This paper makes a set of radical proposals that build on current plans. If adopted over the next several years, these would enable the UK to retain its world leadership in digital terrestrial broadcasting bringing significant incremental benefits to every stakeholder – consumers, manufacturers, broadcasters and media companies, network operators, regulators, and the Government.
Proposals – For Discussion
We take as a working assumption that digital switchover will be completed by 2012 and that Ofcom’s proposals for the sixth multiplex will eventually go ahead, offering HDTV services using MPEG4 and DVB-T2. We believe these steps are not sufficient to meet consumers’ or industry’s needs. (It should also be noted that a separate proposal to introduce terrestrial HDTV using DVB-T and MPEG4 has been made.)
Download pdf HDTV and Mobile TV: post Digital Switchover
That paper contributed to a UK and an international dialogue that has led to the recent publication of proposals from Ofcom and the public service broadcasters to introduce terrestrial HDTV services in the UK, based on the new DVB-T2 standard. Ofcom has also indicated that it plans to auction off 14 of the UHF channels currently used for analogue broadcasting, leaving 32 channels to carry 6 digital TV multiplexes (networks).
Last autumn the authors of the original paper came together again to build on the progress made over the previous 18 months and to develop their earlier proposals taking into account the full potential for digital terrestrial broadcasting in the UK. This paper makes a set of radical proposals that build on current plans. If adopted over the next several years, these would enable the UK to retain its world leadership in digital terrestrial broadcasting bringing significant incremental benefits to every stakeholder – consumers, manufacturers, broadcasters and media companies, network operators, regulators, and the Government.
Proposals – For Discussion
We take as a working assumption that digital switchover will be completed by 2012 and that Ofcom’s proposals for the sixth multiplex will eventually go ahead, offering HDTV services using MPEG4 and DVB-T2. We believe these steps are not sufficient to meet consumers’ or industry’s needs. (It should also be noted that a separate proposal to introduce terrestrial HDTV using DVB-T and MPEG4 has been made.)
Download pdf HDTV and Mobile TV: post Digital Switchover
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