http://www.itweb.co.za/index.php?option=com_content&view=article&id=38945:sadiba-slams-isdbt-trials&catid=49
The Southern African Digital Broadcasting Association (Sadiba) has declared the field test of digital TV standard ISDB-T a failure, with just days to go before the region makes up its mind about what standard to use.
ISDB-T went on air in Gauteng for a few days earlier this month. The test of the Brazilian upgrade to the Japanese ISDB-T standard sought to prove claims that it can work in a local environment.
SA initially approved digital migration using the European DVB-T standard in a 2006 Cabinet meeting. Earlier this year, however, the Department of Communications (DOC) shocked the industry when it said it was looking into the possibility of using ISDB-T instead.
Proponents of DVB-T have heavily criticised the DOC's decision, arguing that switching now would delay migration by several years and add even more cost to the R700 million that has already been spent. SA aims to have digital TV on air commercially within a year. The international deadline for switching over from analogue to digital TV is mid-2015.
In addition, the ISDB-T standard has never been implemented on an 8MHz frequency ? which is in use in SA ? and developing equipment and standards for SA's channel spectrum will add more costs and complications to migration, argues the local industry.
Now the field tests, spearheaded by a contingent of Japanese engineers and diplomats, have been branded a failure. Sadiba yesterday released a report claiming the trial was ?highly problematic? and only achieved 8% of its objectives.
Sadiba's report slamming the trial was issued just days before Southern African Development Community (SADC) communication ministers are due to declare what standard the region will use. Communications minister Roy Padayachie has also indicated SA's decision will be announced by mid-December.
Failed
The signal, using the ISDB-T standard, went on air in Pretoria, Johannesburg and Helderkruin, on Johannesburg's West Rand, for a few days in the first week in November. All of the South African Broadcasting Corporation (SABC) channels, as well as 19 radio stations, were carried.
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The tests aimed to assess coverage through ISDB-T, whether ISDB-T was compatible with current analogue broadcast, and examine picture sound and quality, as well as reception modes.
In addition, mobile and fixed reception was set to be verified and the trial also wanted to confirm that a single frequency network (SFN) can work. A SFN is a network in which several transmitters send out the same signal over the same channel. It is vital as the broadcasts will overlap each other, but should not cause interference.
However, argues Sadiba, very few of these objectives were met. The body says the vital SFN was never established, picture quality was poor, and reception modes were never measured scientifically.
Sadiba, founded in 1997, is a voluntary industry forum that aims to promote a coordinated market-driven introduction of digital broadcasting technologies in the Southern African region.
It argues the trial can not be declared a success and was not ?conducted in an open and transparent manner?.
In addition, the association claims, key industry stakeholders, members of the academia and third-party engineering experts were unable to participate.
As a result, says Sadiba, no independent measurements were done to show the trial worked. ?Any claims made on any success or proof of performance achieved is solely made by proponents of the ISDB-T system, and has not been verified, studied or assessed in any substantial manner by any independent entity or stakeholder,? states the report.
Moreover, says Sadiba, because transmission was massively disruptive and resulted in interference with other broadcasts, the signal was switched on and off to reduce interference. This trimmed the amount of time the broadcast was on air, reducing the chance of actual statistical measurements, it argues.
?It is Sadiba's view that the ISDB-T trial has not provided South African stakeholders with any new insights, or reason to consider it as an alternative standard to the adopted national standard DVB-T. Considering the number of objectives achieved against those not achieved, it is not possible to claim that the trial was a resounding success,? the report concludes.
Hitting back
However, the Japanese have hailed the trial as a success. Speaking through a translator after the test was wrapped up, Tetsuo Yamakawa, vice-minister of internal affairs and communications, told ITWeb the local trials were ?very successful?.
Masa Sugano, first secretary in the SA Japanese Embassy's economic and commercial unit, has hit back at the Sadiba report. ?The choice and weighting of the objectives by Sadiba is highly arbitrary and amateurish, and does not deserve a comment.?
Sugano argues the limited time ISDB-T was on air and the fact that there have not been any comparisons between the different standards is a problem of Sadiba's own making.
?DVB-T proponents have fiddled around, choosing to spend their time debating on an unneeded and unusual standard that would close off the market from competition in favour of a few established original equipment manufacturers,? she says.
Sugano argues that several Latin American countries, which adopted ISDB-T, got commercial broadcast on air within 18 months, while SA has yet to move beyond the trial phase. Sentech has been testing DVB-T, and etv and M-Net have been testing its upgrade, DVB-T2, which Sadiba says is successful.
Moreover, argues Sugano, the field test was limited by constraints in licensing conditions and could not ever be a comparison with DVB-T or DVB-T2. ?Much of Sadiba's criticism relies on notions such as lack of published data or the lack of use of a SFN.?
She argues it would be misleading to compare any data without equal parameters and the licence conditions did not allow for a single frequency network test. ?A formally sanctioned comparison test would be the most reasonable way for this to take place,? says Sugano.
Courtesy of ITWEB..
