Two important events took place during last week’s meetings of the ITU Radiocommunication Sector (ITU-R) Working Parties 6A and 6C, which respectively focus on transmission-related aspects of Terrestrial Broadcasting Delivery and on programme production and quality assessment of radio and television broadcasting.
ITU and the EBU (European Broadcasting Union) held a joint workshop to raise awareness among ITU Member States and sector members of the risk of interference into the reception of the Digital Audio Broadcasting system (DAB).
In addition, the BBC and NHK demonstrated how current standard dynamic range (SDR) images can be converted to high dynamic range (HDR) and how to use HDR images for SDR HD distribution without degrading the quality.
The joint ITU-EBU workshop focused on the risk of interference into the reception of the DAB system from non-radiocommunication devices, like light-emitting diode (LED) lighting systems and other apparatuses using switch-mode power supplies.
Participants discussed the results of measurements and tests in multiple countries as well as the role of administrations in limiting interference and information about ITU’s related activities.
Several countries in Europe have either decided or are considering switching over from analogue FM Radio to DAB. This is accompanied by an increased number of DAB receivers in use. At the same time, the use of LED lighting systems is massively growing – and there is an increasing number of low-cost, poorly designed gadgets, domestic appliances, multi-media equipment, personal computers, and tools using switch-mode power supplies. This has led to more cases of interference to DAB reception reported to administrations and broadcasters.
Two EBU member organizations – NRK from Norway and TSR from Switzerland – and one European Broadcast Network Operator, Arqiva from UK, presented their respective results of field investigations and measurements and explained their findings and analyses of the factors causing the interference cases.
In the second part of the workshop, presentations from the Norwegian spectrum regulator and interventions from other administrations present in the audience showed the possible role of administrations to solve the interference cases.
The EBU representative to the International Special Committee on Radio Interference (CISPR) gave a remote presentation on the important role of CISPR in setting the limits of emissions that the non-radiocommunication devices should not exceed.
Finally, speakers from ITU, BBC and EBU presented the ITU-R role in specifying the system parameters, planning parameters and protection requirements of the broadcasting systems.
It was noted that the problems experienced with LED lighting systems should be seen as more of an illustration of the deeper underlying problems involved. A common factor is the near universal use now of switch-mode techniques in power supplies and AC-to-DC and DC-to-DC power converters. These tend to produce high levels of radio-frequency (RF) energy, which appears as radiated emissions across wide ranges of frequency and leakage of RF energy onto electrical mains wiring. Increasing levels of RF energy on mains wiring then causes thermal stress and rapid ageing of filter components in other connected equipment, thus creating a vicious circle of degradation and increasing RF noise. These factors are particularly evident with LED lighting systems on account of their ubiquitous use these days.
Looking to the future, action is necessary to improve equipment design and standards to reflect the proliferation of electrical and electronic equipment and minimize levels of RF noise in the environment. This is essential for ensuring that the planning criteria for radiocommunication services and resulting service availability are not compromised by a rising noise floor.
The obvious problems presented by interference to DAB by LED lighting have had the benefit of exposing the underlying problems, leading to better collaboration between ITU and CISPR in finding solutions.
“This workshop has emphasized how important our collaboration with CISPR is in order to continue to fulfill ITU’s role in developing a sustainable ecosystem of radiocommunications throughout the world,” says François Rancy, Director of ITU’s Radiocommunication Bureau.
All presentations and information about the programme and the speakers can be found on the ITU website using the following link: Workshop on ‘Interference to DAB reception.’
It will be many years until all television production and distribution use the new HDR TV formats specified in ITU-R Recommendation BT.2100.
Until then, broadcasters and programme makers will rely on high quality format conversion between the standard and high dynamic range production formats, to allow SDR content to be included in HDR programmes, and to allow HDR programmes to be distributed on existing SDR television networks.
The BBC and NHK joined forces to demonstrate two of the complementary SDR to HDR and HDR to SDR format conversion methods developed by the ITU-R, operating at UHD 4K resolution in real-time.
Using a wide range of SDR test material, delegates could see how effectively these techniques can be used to enhance the contrast of SDR content, to better match the appearance of natively produced HDR content.
In a second demonstration, clips from BBC and NHK HDR programmes were used to show how good conversion can be used to compress highlights, and automatically convert HDR programmes to SDR. The BBC used this process to automatically convert the HDR images from the recent Royal wedding in England to standard HD for an estimated 1.9 billion viewers worldwide.
“Television is the most consumed and most influential media across the world. We are proud of the leadership shown by the ITU-R in the continued enhancement of television.” — François Rancy, Director, ITU Radiocommunication Bureau
What was clear from the demonstrations was the thought that the ITU-R put into creating practical end-to-end solutions that work for broadcasters and programme makers. These conversion processes will allow programme makers to freely mix HDR and SDR sources in HDR production, and to automatically create SDR versions of a programme from the completed HDR programme master; thereby avoiding the need to separately produce both HDR and SDR programme variants.
“The media experience continues to evolve thanks to the constant efforts of ITU-R Study Group 6 to produce global standards for programme production and distribution using the most advanced technologies,” says Mr. Rancy. “Television is the most consumed and most influential media across the world. We are proud of the leadership shown by the ITU-R in the continued enhancement of television.”
View the photos from the workshop on ITU’s Flickr here.
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