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PMSE upheaval flies forward as Ofcom accelerates 700MHz clearance

UK broadcasters and wireless equipment users have been prepared for changes to spectrum allocation but the situation is now moving faster than expected

UK broadcast and frequency regulator Ofcom is to speed up the clearance of the 700MHz band to make frequencies available for mobile data operators by the second quarter of 2020. This is 18 months earlier than originally proposed and could have serious implications for digital terrestrial television (DTT) broadcasters and wireless microphone users in the PMSE (Programme Making and Special Events) sector.

Ofcom says, “The benefits of accelerating the programme… outweigh the costs of doing so and… can be achieved whilst minimising disruption to viewers and without compromising our objective of safeguarding the benefits that PMSE provide.” The government is to support a grant scheme for PMSE users who have to leave the 700MHz sooner than anticipated.

Earlier this year Ofcom decided on 960-1164MHz as the new home for PMSE. Also known at the Air Band this is currently used by DME (distance measuring equipment) transponders on commercial aircraft in UK airspace. Ofcom says this arrangement will be implemented “in accordance with spectrum management rules agreed with the Civil Aviation Authority”.

During September the APWPT (Association of Professional Wireless Production Technologies) raised concerns over the allocation of 960-1164. Specific questions are: if there was an air traffic accident caused by interference, what would be the liability of any PMSE operators involved; will PMSE users receive compensation or support for having to re-equip to operate in the ‘new’ band; and who would ultimately pay if PMSE operators were penalised by clients for poor quality audio?

The latest organisation to join the argument is the DTG (Digital Television Group), which formed a PMSE Group earlier this year. This is supported by the Department of Culture, Media and Sport (DCMS) and Ofcom with the aim of delivering “timely enhancements both to PMSE audio equipment available in the market and to the operational arrangements that enable its use to be maintained while safeguarding spectrum users”.

The DTG held an inaugural meeting of the PMSE Group in July (pictured), inviting wireless equipment users and manufacturers as well as its own members. A number of leading figures in the PMSE/spectrum debate did not attend. These included Alan March, senior manager for spectrum affairs at Sennheiser and a key spokesman with BEIRG (British Entertainment Radio Industry Group), who objected because the DTG was asking non-members to pay £3,500 to join the organisation if they wanted to be at subsequent events.

Alex Buchan, head of Wireless Technologies at the DTG, acknowledged that the DTG had mainly been involved in the development of DTT rather than PMSE but explains its role now is as an “UK collaboration centre for digital media innovation”. He adds, “Many of our members, such as Sony, are involved in broadcast PMSE. There isn’t an existing forum for people to share their experiences of the 700MHz situation, which is why we wanted to set this up and involve non-members who may be worried by what is happening. We offered a heavily discounted rate but that was still too much for smaller organisations.”

A full DTG PMSE meeting was held in September, with an another scheduled for 23 November. Buchan said the second event was well attended, with contributions from APWPT, Ofcom and the BBC. Mark Waddell, a lead BBC R&D engineer, was elected chair of the PMSE Group.

A major concern voiced by the DTG and other interested parties is the loss of spectrum for PMSE and possible inference in the Air Band. “We’re going to lose 96MHz and 960-1164 is not full mitigation for the loss of the 700MHz band,” says Alan March. “Manufacturers are developing new equipment but the real problems could be in the mid to long term.”

Tuomo George-Tolonen, manager of the Pro Audio Group at Shure Distribution, adds that not all the Air Band would be available as the requirements of the existing user need to be protected. But he says the lower portion has “some fairly usable spectrum available”. To address this Shure has produced prototype equipment that is being tested at various locations in the UK.

“So far these have proven to be positive from an operational standpoint,” George-Tolonen says. “The concerns that remain and need to be answered are if further DME transponders are to be introduced into this band over the coming years it would noticeably reduce the available spectrum for PMSE, which would be a concern for the longevity of the band. Secondly, 960-1164MHz is currently a UK solution only, which would severely impact the appetite manufacturers have for producing equipment.”

As George-Tolonen observes, it is still too soon to say how viable the Air Band will be for PMSE. If it is successful that could lead to clearing frequencies below 694MHz, which might deliver the “killer blow” to PMSE.