Radio mic challenges past, present…and future (part 2)

It is a fact that digital wireless microphones operate in bands coincident or very close to those of the DVB-T transmitters. To understand the problems that can arise – some of which have already occurred, primarily in areas of high population/RF density – we must consider how DVB-T involves the use of all the television channel, leaving no room for radio microphone frequencies. In recent times, it has become essential to deploy only wireless microphones with a high value of squelch, at least up to 50/60 dBuV, and flexibility in bandwidth > 200/300 MHz.

As of 1 January 2013, spectrum allocation changes mean that it is no longer possible to deploy radio equipment operating in the range between 790 and 870 MHz after this band was assigned to mobile applications. With mobile broadband services on the rise, it’s a situation that will only intensify, obliging radio mic users to convert existing equipment or purchase new systems operating in different bands.

Sennheiser is among the companies to have readied an extensive range of wireless systems able to cope with the new spectrum regime. We therefore invited Paul Corchia from Italian pro audio importer Exhibo Spa – whose brand portfolio includes Sennheiser – to describe ‘from the inside’ the current landscape for radio mics and the response of the Sennheiser organisation.

Corchia told SVG Europe: “In short, we could say that if in certain geographical areas characterised by the presence of few television carriers (including DAB which is coming …!) the symbiosis between wireless microphones and DVB-T transmitters is problematic but overall still acceptable; on the [other hand], in other, densely populated areas the search for a free channel on which to operate with one or more wireless microphone may easily become a nice stroke of lottery.

“Besides, with the arrival of [the] 4G or LTE threat, there will be a new problem of further [occupation] of the channels used by TV broadcasting, resulting in an increased anxiety for those who must operate in the same radio bands.

“To protect its customers, Exhibo has therefore decided to solve proposing two major steps: the first comes from the laboratory and internal technical assistance which provides a wireless microphone recanalisation of those devices already in possession of the customers [now operating] above the fateful threshold of 790 MHz UHF.

“The second important initiative provides a ‘discount scrapping’ [scheme for] the apparatus of this type which guarantees the customer a big discount on the purchase of equipment adapted to the new regulations.

“For this purpose are proposed the Evolution G3 Series, 2000 Series, and of course the top of the range Series 3000/5000, which are differentiated by the large amount of available bandwidth (MHz respectively 42-75-180).

“For those customers who may want to follow other paths at the time of purchase in favour of a radio microphone system, we recommend keeping in mind that today it is crucial to verify that the new equipment meets precise requirements in order to avoid running into very serious problems. In a very short time, with the increasing spread of LTE these issues will become more and more evident and frequent.”

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