Prof. Dr. Jörg Sennheiser, Chairman of the Supervisory Board of Sennheiser electronic GmbH & Co. KG, and Gerrit Buhe, Head of Professional RF Systems Development, have been nominated for the German Future Award, the German President’s prestigious award for technology and innovation. The nominees aim to revolutionise the stage and live performance sector with their digital handheld RF wireless transmitter. This new microphone means that the benefits of digital technology are now also available to the field of wireless microphones. Fifteen years of development in cooperation with institutes, companies and universities as well as an investment of more than 20 million euros have gone into this technology, which also allows considerably more microphones to be accommodated within a given frequency range.
 

Prof. Dr. Jörg Sennheiser, Chairman of the Supervisory Board, and Gerrit Buhe, Head of Professional RF Systems Development

Microphones are one of the last bastions of analogue audio technology. Whereas mixing consoles, effect equipment and audio processing have long since become digital, the microphone has stubbornly resisted the advance of digital technology. Digital models of wired studio microphones have been available for some years now, but a high-quality digital wireless microphone has yet to make its breakthrough. The few prototypes presented at trade fairs and exhibitions rely on data compression and

therefore do not transmit the complete signal, or they require a wide frequency spectrum, making them unsuitable for use in professional production conditions, especially when a large number of microphones are being used in parallel. “Our new product is the result of a long learning curve,” explained Prof. Dr. Jörg Sennheiser. “A lot of approaches had to be rejected during the development period because the audio quality was too low. But from every approach that we rejected, we gained valuable ideas for a new solution.” 
 

Digital without data compression

Digital RF wireless microphone from Sennheiser

Scrupulously monitored by the ever-critical ears — and eyes — of master sound engineers, digital microphones have to prove that they are at least as good as their analogue counterparts. That is possible only if data compression is avoided, as compression is not only audible, it also truncates the original sound — and any recording quality that is lost at the beginning of the production chain can never be recovered later on. In other words, the audio signal must remain available without any alteration.

As if that wasn’t a great enough challenge …
… a further problem area arose during the development: the frequencies at which wireless microphones transmit. In 2004, the European Telecommunication Standard Institute (ETSI) announced that digital wireless microphones would also have to manage with the narrow transmission band allocated to analogue wireless microphones — in spite of the much higher data stream involved. That — and the fact that the transmission frequencies were not protected for microphones — meant the end of the line for a digital system that Sennheiser sold on the US market together with a partner.
 

“The requirements constantly increased during the development period, so it was a good thing that we had set our own demands very, very high right from the start,” said Gerrit Buhe, Head of Professional RF Systems Development at Sennheiser. “The ETSI requirements meant that we were faced with the challenge of developing a special process to squeeze the “broad” digital through the “narrow” prescribed transmission channel of 200 kHz.”
 

“At the same time, we were actively involved in committee work to ensure the availability of microphone frequencies,” Buhe continued. “Several colleagues work on this aspect alone. With the introduction of digital television, people thought that frequency resources would be released and could be sold to other services. But they ignored the fact that wireless microphones use these very frequencies for musicals, theatre, sports and news reporting and TV productions. As a result, the development had to be accompanied by considerable committee work.”
 

The breakthrough
On the development level, the major breakthrough has already taken place. “With the very latest knowledge already in our briefcase, supported by refined simulation techniques and our wide experience of digital transmission technology, we signed a cooperation agreement with the Technical University of Hamburg-Harburg in 2002,” said Prof. Dr. Sennheiser. “The joint design work finally allowed us to develop a system that passed the initial tests in the presence of even the most critical sound engineers with flying colours.”
 

No signal distortions whatsoever could be heard, and the system fully exploited the benefits of digital technology: clear, noise-free sound even with a low radio signal and a high range. One of the most important criteria in digital transmission was judged as being excellent: the latency of the signal, in other words the time delay caused by electronic and numerical processing, is very low.
 

Prof. Dr. Jörg Sennheiser points out a further advantage: “Because high-quality digital transmission processes react very sensitively to so-called non-linearities, our transmitters and receivers are designed to be so linear that they almost completely avoid the usual intermodulation products. In conventional systems, these occupy valuable transmission space, which we can use in our new system for even more wireless microphones. We can therefore speak of sustainable frequency usage.” “We will be able to operate twice as many wireless channels within the given television channels,” said Gerrit Buhe.
 

Receiver for the digital RF wireless microphone

In contrast to conventional wireless technology, the receiver in the new Sennheiser system will work over the entire UHF frequency range. Several analogue systems would be required for this purpose. This high degree of flexibility means that the system can be used worldwide in the different frequency ranges that are permitted in the different countries.

 

Outlook
The digital microphone system is protected by international patents. The pre-series models are currently undergoing intensive testing at key customers and master sound engineers. And as soon as they give the go-ahead, the system will go into series production.
 

The Sennheiser Group, with its headquarters in Wedemark near Hanover, Germany, is one of the world’s leading manufacturers of microphones, headphones and wireless transmission systems. The family-owned company, which was established in 1945, recorded sales of over €395 million in 2007, 83% of which were generated abroad. Sennheiser employs almost 2,000 people worldwide, around 55% of whom are in Germany. Sennheiser has manufacturing plants in Germany, Ireland and the USA, and is represented worldwide by subsidiaries in France, Great Britain, Belgium, the Netherlands, Germany, Denmark (Nordic), Russia, Hong Kong, India, Singapore, Japan, China, Canada, Mexico and the USA, as well as by long-term trading partners in many other countries. Also part of the Sennheiser Group are Georg Neumann GmbH, Berlin (studio microphones), K + H Vertriebs- und Entwicklungsgesellschaft mbH (Klein + Hummel studio monitors, installed sound) and the joint venture Sennheiser Communications A/S (headsets for PCs, offices and call centres).

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You can find more information on the German Future Award at

http://www.deutscher-zukunftspreis.de/?q=de/content/deutscher-zukunftspreis-2008
 
You can find all the latest information on Sennheiser by visiting our website at http://www.sennheiser.com/, or by contacting:

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Tel.: +49 (0)5130 600 329
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E-mail: edelgard.marquardt@sennheiser.com