Just as the European Commission throws its weight behind endorsing DVB-H as the one true European standard for mobile TV, one of the ‘near dead’ rivals in the form of T-DMB, has begun to make the kinds of noises you would expect from a standard that had already won the war, rather than finding itself defeated in almost every market in the world except Korea.
This week T-Systems said that it is launching a test broadcast for mobile TV in the Netherlands offering five TV stations on cell phones working with Mobiele Televisie Nederland (MTV NL) despite the fact that T-DMB, or its audio parent DAB, has yet to be offered a public multiplex in the Netherlands and the fact that KPN has been preparing its own DVB-H system since 2005 through the consortium Digitenne, which binds KPN, NOB, and Nozema, a Dutch TV transmission operator planning to offer DVB-T and DVB-H services simultaneously using Harris transmitters and Nokia handsets.
During 2006 T-DMB specialist RadioScape operated a trial for T-DMB TV in the Netherlands and we suspect this new trial has emerged out of that.
Elsewhere Sweden’s Factum Electronics, a specialist supplier of DAB based networks, has said this week that it has won contracts to supply the Czech network operator Teleko and the French network operator Towercast with digital broadcasting systems.
These are for systems offering the new, more efficient version DAB/DMB with Towercast planning to offer DMB video services as well as audio.
Factum says that it now has customers in Belgium, Denmark, Germany, Hungary, Iceland, Italy, Norway, Sweden, Switzerland and the UK.
And finally this week a new multi-year European project to co-operate with China over T-DMB was announced as MODIBEC, which brings together key players from Europe and China, including government, trade bodies and the private sector and a statement points out that DAB and its family of standards is the only European multimedia broadcasting standard accepted for digital broadcasting by SARFT, China’s state broadcasting regulator.
It is that last statement about China that perhaps offers some salvation for the T-DMB standard as a video delivery mechanism for mobile TV.
While in Germany and the UK, where respectively T-DMB and DAB IP have been used to offer mobile TV, and have been unmitigated disasters in terms of take up and the quality of video offered, in China DAB licenses have already been approved in four Chinese districts. These will be used to broadcast both audio and mobile TV in Beijing, Shanghai, Dalian and Guangdong Province, which have combined populations of around 50 million people.
Faultline pointed out in our report and forecast this year on mobile TV (email [email protected] for details), that although china is developing its own mobile TV standard, T-DMb services, with Samsung devices, were likely to be the back-up plan to getting mobile TV up and running in China by June 2008, in time for the Olympics.
Although 500 million people worldwide are said to be within range of a DAB radio system, across 40 countries including Canada, Australia, across Europe and in India, China and South Africa, and there are more than 1000 services actually live on air, as a video delivery system it is only successful in Korea and despite all the bragging on the T-DMB web site, it is only this temporary advantage in China that is keeping it alive.
World DMB even perversely boasts that it uses less power than DVB-H, but it is not a bursting technology, so that the radio has to be on permanently, whereas a DVB-H radio is only on around 7% of the time. DVB-H will likely use around 190 mW when active and an aggregate of perhaps 45 mW. DAB version 1 used around 250 mWs constantly and although there have been improvements in chips from companies like Frontier Silicon, they are nowhere near that overall average of 45mW, and so are not as suitable for mobile handsets as any of DVB-H, DVB-SH, MediaFLO or MBMS.
In fact using DAB IP it is possible to deliver multiple bursts of IP data packets and emulate a kind of time slice, which is how British Telecom runs its Movio service in the UK. DAB-IP is a way of sending pure IP signals using the enhanced packet mode that is built into the DAB standard, and has been adapted by some operators to carry video.
While it is true that DAB is widely used in national multiplexes throughout Europe, these multiplexes were design for audio services, and while there is substantial penetration of digital radios in the UK, where there are around 8 million devices, and also in Germany, Denmark, Norway and Switzerland, these may be totally unsuited for pure video. Off the back of some devices success in China, it is possible that World DMB may create a kind of second tier of services. We had Italy’s broadcaster RAI last week saying that it was forced into offering Mobile TV as T-DMB, because it had no spectrum for DVB-H, and so this sub-community of mobile TV offerings has to find a way forward to survive against the richer, higher quality services coming out of pure datacast systems such as DVB-H.
Having household devices such as microwaves and fridges fitted with T-DMB music and video devices, and offering radios which are GPS devices along with cheap portable music and video players, seems to suggest that T-DMB can survive as digital radio, with slow take up, showing a few videos every now and then, as a cheaper option for people that cannot really give their full attention to TV right now.
The main advantage of using DAB is that in many countries there are existing multiplexes and in many where there are not, there is existing spectrum allocated for building one. The system was designed in Europe and initially came from a funded European project, one of the most successful, named Eureka 147.
Much of the criticism that is leveled at DAB comes from the spectrum which has been allocated to it in various parts of the world. Band III VHF which runs from 174 MHz up to 230 MHz radio spectrum would seem ideal having very long distance propagation features, but part of the L-Band spectrum from 1452 to 1492 is also allocated to DAB, which makes it impossible for use in the US, which uses this as military spectrum. These networks are also expensive to build because the short propagation distances.
In the US this has meant that the transition from analog radio stations to digital radio stations needed another route which has led to the existence of both digital satellite radio, with two US companies operating with 12.5 MHz of spectrum each in the S-Band range sending digital audio radio signals from a remote satellite, with a full US footprint and also to a company called iBiquity Digital, coming up with a US digital audio system called HD Radio.
Another criticism is that T-DMB has just gone through a fundamental re-working. DAB was originally launched using MPEG 1 layer 2 for audio, but this is seen as not a suitable way of delivering audio for TV, so where T-DMB is used DAB has used the much improved HE-AAC codec also called AAC+. The video is encoded using H.264.
The choice of codec was originally designed for high quality stereo, using between 192 and 256 kbps, But since this is now enough to provide both sound and video this is seen as wasteful of the spectrum, and anyway, none of the radio stations use it either, as it is too expensive, with most opting for between 80 kbps and 128 kbps.
That has led to a recasting of the standard with DAB 2.0 in November 2006, with WorldDAB (now renamed WorldDMB) announcing the adoption of AAC+ and setting up the situation that where countries that have already embraced DAB, will have all their existing receivers incompatible with the new DAB standard, with new receivers just becoming available.
Another issue in the past has been that the power levels required for T-DMB chips (DAB chips) were designed for radios, which either have access to mains power or to larger batteries than mobile handsets or other portable players, and so the chipsets were never really built to offer long term battery life.
DAB spectrum has to be allocated in slices of 1.536 MHz which translates to 1536 OFDM sub-carriers with 1 kHz of sub-carrier spacing each. The gross data capacity for the entire DAB signal is close to 3 Mbps, but the main service channel offers just 2.3 Mbps which really only gives a net useful payload of between 1 and 1.7 Mbps.
In Korea each of these channels will offer 3 TV stations, plus more audio and data channels, so the quality CAN be pretty good (around 440 Kbps each) and this proves that contiguous side by side spectrum can be received at a handset with no problems using the same radio, and to customers this appears to be a TV service with 11 or 12 channels available, even though it comes from multiple multiplexes. This is not the case when a multiplex is shared with 20 or more radio channels, as existing multiplexes tend to be.
T-DMB will be around for a long time, but touting it as having ‘won’ the core standards war against DVB-H in Europe is so far from the truth that it makes the outpourings of World DMB look slightly untrustworthy. Instead it is a potentially dominant radio standard, outside of the US, which has a spattering of low class video capabilities, unless you completely ignore the international spectrum roadmap, as Korea has done.
And saying otherwise just confuses operators who have enough choices in front of them without one that just doesn’t have any of the technical advantages to be able to offer a full suite of 10 or 20 video channels.