1segの概要と日本のモバイルTV

1seg is a digital TV broadcasting system in Japan that allows viewers to watch TV on their mobile devices.

It's a one-segment system, meaning it uses a single frequency to broadcast a single channel.

This system was developed by NHK, Japan's public broadcasting organization, and was first introduced in 2006.

1seg uses a special antenna and a mobile phone or digital camera to receive the broadcast signal.

The signal is then decoded and displayed on the device's screen in real-time.

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The ISDB-T system uses the UHF band at frequencies between 470 and 770 MHz, giving a total bandwidth of 300 MHz. This bandwidth is divided into fifty channels, named channels 13 through 62, each 6 MHz wide.

Each channel consists of a 5.57 MHz wide signalling band and a 430 kHz guard band to limit cross-channel interference. The signalling band is further divided into 13 segments, each with 428 kHz of bandwidth.

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The 1seg system uses QPSK for modulation, with 2/3 forward error correction and 1/4 guard ratio. The total datarate is 416 kbit/s.

The television system uses an H.264/MPEG-4 AVC video stream and an HE-AAC audio stream multiplexed into an MPEG transport stream. The maximum video resolution is 320x240 pixels, with a video bitrate of between 220 and 320 kbit/s.

The system uses a Broadcast Flag-like structure contained in the "Copy Control Descriptor" within the broadcast for conditional access and copy control. This forces the device to encrypt stored recordings and disallows making a copy of the recording.

Here are the key technical specifications of the ISDB-T system:

The ISDB-T system uses the UHF band at frequencies between 470 and 770 MHz, giving a total bandwidth of 300 MHz.

Each channel is 6 MHz wide, consisting of a 5.57 MHz wide signalling band and a 430 kHz guard band to limit cross-channel interference.

In 1seg broadcasting, modulation is done using QPSK, with 2/3 forward error correction and 1/4 guard ratio. The total datarate is 416 kbit/s.

The television system uses a H.264/MPEG-4 AVC video stream and a HE-AAC audio stream, multiplexed into a MPEG transport stream.

The maximum video resolution is 320x240 pixels, with a video bitrate of between 220 and 320 kbit/s.

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The One Seg receiver circuit is made up of several key components. It includes an antenna and a filter, along with a tuner circuit.

The tuner circuit is made up of a LSI (Large Scale Integration) chip that handles the tuning, as well as other components like a crystal oscillator and passive components.

In the past, a One Seg tuner module was commonly used, which integrated all these components into one module. However, nowadays, it's more common to see a single LSI chip that combines the tuner and OFDM demodulation functions, along with peripheral components, directly integrated onto the main circuit board.

This shift towards a more integrated design has made the circuit board more compact and efficient.

Intermittent operation is a smart way to reduce electric power consumption in standby mode. By controlling activation and termination of tuners, you can significantly decrease power usage.

In one method, reception with intermittent operation of 27 symbols from the initial symbol of the OFDM frame to the emergency warning activation flag is used. This is known as symbol decimation.

Through experiments on circuit adjustment, it was found that seven symbols are needed from the time the tuner power is turned on to the time when AGC operation is stabilized. This is a crucial factor in achieving stable AGC operation.

The tuner activation time is the total time for 34 symbols, which is a result of combining the seven symbol stabilization time with the 27 symbol decimation time. This allows for a significant reduction in power consumption per frame.

With symbol decimation, power consumption per frame can be reduced to 34/204 = 1/6, which is approximately 17%. This is a substantial decrease in power usage.

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To further reduce power consumption, frame decimation can be applied. In this case, the tuner is not activated for seven subsequent frames after conducting symbol decimation on the leading frame. This enables the number of tuner activations to be reduced further, to 1/8.

By applying both thinning methods, symbol decimation and frame decimation, the power consumption of the tuner can be reduced to 1/48. This is a remarkable achievement in reducing power usage.

The 1seg service is a game-changer for mobile and hand-held terminals, offering interactivity and the ability to enjoy broadcasts anywhere, anytime.

One-Seg has become popular in Japan since its launch in April 2006, and it's easy to see why - with its ability to combine multiple One-Seg signals on one frequency without interfering with received waves, it achieves high frequency utilization efficiency.

The connected One-Seg re-transmission system is a key feature of the service, allowing for efficient re-transmission of One-Seg signals with low power consumption.

This system is particularly useful for emergency warning broadcasting, as it can be remotely activated and has a low standby power consumption.

Here are some of the key features of the connected One-Seg re-transmission system:

The service expansion of One-Seg is also noteworthy, with the ability to easily add original content and expand the service area by simultaneously transmitting localized content.

The connected system is a key feature of 1seg technology, allowing for the re-transmission of One-Seg signals on a single broadcast channel. This is achieved through the extraction of segments from multiple broadcast waves, repositioning them in a single broadcast channel, and re-transmitting the channel.

A maximum of 13 waves can be connected together within a single broadcast channel, making it possible to use the remaining unused segments to transmit localized content, such as municipality information or shopping center information. The system eliminates the need for guard bands, ensuring stable re-transmission without signal degradation.

The connected system also allows for efficient power consumption, as only One-Seg signals are transmitted. This is a significant advantage, especially in areas with limited power resources.

The connected method of One-Seg re-transmission is a clever way to re-transmit broadcast signals. It extracts segments from multiple broadcast waves, repositions them in a single broadcast channel, and re-transmits the channel.

This method allows for a maximum of 13 waves to be connected together within a single broadcast channel. If there are less than 13 waves, the remaining unused segments can be used to transmit localized content.

The connected method is efficient, as it uses only one channel for re-transmission, and can transmit 13 One-Seg services per channel. This is a significant improvement over traditional methods.

Here are the key features of the connected One-Seg re-transmission system, summarized in a table:

The connected method has been evaluated in a laboratory experiment, which confirmed that there is no degradation of reception characteristics due to connected transmission.

Connected systems are often associated with IoT devices, which can be controlled and monitored remotely.

These devices can range from simple sensors to complex machines, all connected through the internet.

The benefits of connected systems include increased efficiency and productivity, as well as improved data collection and analysis.

For example, a smart thermostat can learn and adapt to a household's temperature preferences.

Real-time monitoring and control are also key features of connected systems, allowing users to stay on top of their devices and systems from anywhere.

This can be especially useful for remote workers or those who manage multiple locations.

Security is a major concern for connected systems, with many devices vulnerable to hacking and cyber attacks.

This highlights the importance of proper security measures, such as strong passwords and regular software updates.

In some cases, connected systems can also improve user experience, such as with voice-controlled assistants that can perform tasks with just a voice command.

This can be especially convenient for those with mobility or dexterity issues.

We constructed a prototype re-transmission device to verify our idea, which consists of three basic components – an RF tuner, a TS re-multiplexer, and a re-transmitter.

The RF tuner receives eight channels of One-Seg signals and demodulates these into an MPEG-2 transport stream (TS).

It then multiplexes the TS of each channel and outputs the result, with the TMCC and auxiliary channel (AC) information of each channel TS packetized and multiplexed together.

The TS re-multiplexer separates the multiplexed TS output from the RF tuner and combines the TS streams of localized content, input externally, and re-multiplexes and outputs the streams.

Each TS is re-multiplexed by a single clock at re-multiplexer.

The re-transmitter performs OFDM modulation by means of IFFT processing all at once.

The position and initial phase of the pilot carrier of each segment is set to the same values as that of segment No. 0, and the TMCC is modulated and re-transmitted based on the received data.

The TS re-multiplexer handles segment allocation of the received One-Seg TSs and the independent content TSs and setting of the transmission parameters of the re-transmitted signals.

The Emergency Warning System (EWS) is a crucial feature of One-Seg, allowing remote activation of One-Seg-compatible video and audio receivers in the event of a disaster.

EWS was first operated in September 1985, and warnings have been issued on a total of 15 occasions.

One such occasion is the broadcast of emergency warnings to mobile One-Seg terminals, which makes especially good use of One-Seg's characteristics and is important for disaster prevention and relief.

In order for One-Seg terminals to receive EWS broadcasts, they must constantly monitor broadcasts for an EWS activation flag included in the TMCC protocol.

This operation requires continuous operation of the demodulation circuit of One-Seg devices, resulting in excessive battery depletion in mobile devices.

To address this issue, a proposed method for demodulating the TMCC carrier using a simple circuit design that does not utilize FFT has been developed.

The proposed method aims to minimize power consumption in standby mode, making it essential for including an automatic emergency warning activation function in mobile devices.

A prototype experiment device based on this proposed method was created using a field programmable gate array (FPGA), as shown in Fig. 5.

In standby mode, the signal received from an antenna is frequency-converted in the tuner.

The activation flag detector monitors the emergency warning activation flag in the TMCC signal.

A sufficiently high accuracy is needed for the activation flag detector to detect an activation flag, so TMCC reception characteristics must be as good or better than One-Seg reception characteristics.

Increasing the number of frames used in the majority decision process improves TMCC reception characteristics.

We can calculate the error rate corresponding to 1 false positive activation flag decision per day using the equation 2.7 × 10.

Japan's mobile TV industry, valued at around $40 billion, is projected to develop into a $4 billion sector.

The high penetration of mobile TV-enabled devices is driving this growth, making it a significant market to watch.

1seg, Japan's mobile digital TV, officially began on April 1, 2006, combining traditional TV broadcasting with digital services.

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Independent programming is a unique aspect of One Seg broadcasting in Japan.

In some cases, One Seg broadcasts are not simulcast with 12 segment broadcasts, resulting in different programming.

For example, Japan's NTV broadcasts a highlight version of a professional baseball game at 21:00, unavailable on analog or digital broadcasts.

This is an example of independent programming on One Seg.

NHK also allows independent programming, with its own channel, NHK One Seg 2, launched in 2010.

The channel features unique programs like "Waon Segu Ranchi Boxu" and "Mori Ko-sama no Ori Kō-sama!".

However, NHK's independent programming was scaled back in 2012 and ended in 2015 due to declining viewership and technological advancements.

Today, NHK broadcasts the same content on both One Seg and full segment broadcasts.

TBS TV has also started displaying the same QR code on One Seg as on full segment broadcasts, starting in 2022.

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Digital TV is a broadcast technology that allows for high-quality video and audio transmission over the airwaves. It's a significant improvement over traditional analog TV.

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Digital TV uses a variety of broadcasting standards, including DVB-T and ATSC, which are used in different regions of the world. The choice of standard depends on the local infrastructure and regulations.

One of the key features of Digital TV is its ability to transmit multiple channels and programs simultaneously, making it possible to receive a wide range of content with a single antenna. This is especially useful for viewers who want to access multiple channels without having to switch between different antennas.

Digital TV also supports features like HDTV and 3D TV, which provide a more immersive viewing experience. However, these features require a compatible TV and a high-speed internet connection.

In Japan, Digital TV is known as "One Seg", a term that refers to the ability to receive a single segment of a broadcast program. One Seg is particularly useful for viewers who want to receive breaking news or sports updates without having to wait for the full program to air.

In Japan, the mobile TV industry has a significant presence, with the Japanese mobile TV industry valued at around $40 billion.

The 1-seg mobile TV service was launched on April 1, 2006, and it combines traditional TV broadcasting with digital services.

This service has a high growth potential, with the industry projected to develop into a $4 billion sector.

The high penetration of mobile TV-enabled devices in Japan is driving this growth, making it an attractive market for mobile TV service providers.

Mobile TV delivery methods, such as the 1-seg service, are becoming increasingly popular in Japan, and this is expected to continue in the future.

いくつかの端末がワンセグ受信に対応している。AQUOSケータイはドコモ向けの端末の一つである。Mobile Hi-Vision CAM Woooはau向けの端末で、HIY01モデルが存在する。

911TはSoftBank向けの端末で、ワンセグ受信が可能である。WS020SHはウィルコム向けの端末で、ワンセグ受信に対応している。

ワンセグに対応したスマートフォンとして、IS03が存在する。PSP用チューナーとしてPSP-S310が存在し、ワンセグ受信アダプタとしてDSテレビが存在する。

PC用チューナーとして、バッファロー製のDH-ONE/U2Pとアイ・オー・データ機器製のGV-SC200が存在する。ワンセグに対応したメディアプレーヤーとしてWALKMAN NW-X1050、WALKMAN NW-A900、gigabeat V30Tが存在する。

シャープのPW-TC920はワンセグ受信に対応した電子辞書である。

Broadcast Markup Language (BML) is a data-transmission service that allows text to be displayed on a 1seg TV screen.

This text contains news, sports, weather forecasts, and emergency warnings like Earthquake Early Warning, all for free.

Further information can be found through links to content on websites, often belonging to the television station itself.

EPG (program guides) is not included, but is transmitted in a separate stream called EIT.

The technology behind broadcasting is quite impressive, and compression plays a huge role in making it all work.

MPEG-2 is the old standard, but H.264/MPEG-4 AVC Baseline Profile 1.2 has taken over with its superior compression quality, achieving a 2-fold or even better compression ratio.

To give you an idea of the resolution, the maximum resolution is 320×240 pixels.

Here are the key specs:

Broadcast Markup Language is a data-transmission service that allows text to be displayed on a 1seg TV screen. This text can include news, sports, weather forecasts, and emergency warnings like Earthquake Early Warning.

The information displayed through BML is free of charge, making it a convenient service for viewers.

You can access more information through links to content on websites, often belonging to the television station itself.

Mobile TV in Japan has been a rapidly growing market since the launch of 1seg in 2006. The industry is valued at around $40 billion and is expected to develop into a $4 billion sector.

The high penetration of mobile TV-enabled devices in Japan is driving this growth, making it a prime example of how mobile TV can be successful in a specific market.

Mobile TV in Japan offers a unique service that allows users to enjoy broadcasts anywhere, anytime. One of the key features of this service is the 1seg system, which allows for re-transmission of signals to improve reception.

The 1seg system uses a H.264/MPEG-4 AVC video stream and an HE-AAC audio stream, multiplexed into an MPEG transport stream, to deliver high-quality video and audio to mobile devices. The maximum video resolution is 320x240 pixels, with a video bitrate of between 220 and 320 kbit/s.

The 1seg system has a number of features that make it well-suited for mobile TV. It uses QPSK modulation with 2/3 forward error correction and 1/4 guard ratio, which helps to ensure reliable transmission. The system also uses a Broadcast Flag-like structure to implement conditional access and copy control.

One of the most innovative features of the 1seg system is its ability to re-transmit signals to improve reception. This is achieved through a process called connected One-Seg re-transmission, which extracts and re-transmits segments of the signal to improve coverage.

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Table 1 summarizes the features of the connected One-Seg re-transmission system:

The connected One-Seg re-transmission system has been tested and proven to be effective in improving reception and reducing signal degradation. The system has also been used to deliver emergency warning broadcasting services to mobile devices.

TMCC reception characteristics are crucial for detecting an activation flag with high accuracy.

The activation flag detector needs to be as good or better than One-Seg reception characteristics, which is achievable with a diversity combining of 4 and a majority decision process.

Increasing the number of frames used in the majority decision process improves the characteristics, allowing for more accurate detection.

The error rate corresponding to 1 false positive activation flag decision per day can be calculated using the equation 2.7 × 10.

This means that with the right setup, TMCC reception characteristics can be reliable and efficient, minimizing errors and ensuring timely emergency warnings.

In fact, with a diversity combining of 4 and a majority decision process, the characteristics can be improved significantly, making TMCC a reliable option for emergency warning systems.

Mobile TV in Japan has taken a unique approach to broadcasting with the concept of "Multi Formation". This format allows for multiple channels to be broadcast simultaneously, making it possible for viewers to watch different programs at the same time.

One of the key features of Multi Formation is the use of "1seg" technology, which enables viewers to receive digital broadcasts even without a cable or satellite connection.

Mobile TV in Japan is a thriving industry, with the Japanese mobile TV market valued at around $40 billion. This impressive figure is a testament to the widespread adoption of mobile TV-enabled devices.

The launch of 1seg, Japan's mobile digital TV, on April 1, 2006, marked the beginning of this exciting development. This innovative service combines traditional TV broadcasting with digital services.

The high penetration of mobile TV-enabled devices in Japan has driven the growth of the mobile TV industry. This has created a lucrative market for service providers.

Mobile TV delivery methods in Japan include various options, but the competitive landscape for future service providers is still evolving.

1seg is a digital television broadcasting standard in Japan, and it's worth noting that it uses a single-carrier modulation scheme called OFDM.

This scheme allows for more efficient use of bandwidth and better resistance to interference.

1seg broadcasts are typically received on portable devices such as mobile phones and personal computers.

These devices are equipped with a tuner that can receive the 1seg signal.

The 1seg standard is designed to provide a low-power, low-cost alternative to traditional digital TV broadcasting.

This makes it ideal for mobile reception and other applications where power consumption is a concern.

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