Sennheiser introduced Spectera at IBC 2024 in Amsterdam, which the manufacturer is calling the world’s first bidirectional wideband system.
Using WMAS (Wireless Multichannel Audio Systems) technology, Spectera reduces wireless system complexity, while at the same time considerably increasing capability, enabling time-saving workflows and offering full remote control and monitoring, including permanent spectrum sensing.
Spectera features bidirectional bodypacks that manage both digital IEM/IFB and mic/line signals at the same time. The solution is remarkably resistant to RF fading and allows for flexible use of the wideband RF channel, for example for digital IEMs with a latency down to 0.7 milliseconds.
Bidirectional digital wideband transmission addresses many of the typical challenges that users, operators and owners of wireless audio systems experience today. These challenges include overly complex frequency coordination and complicated rack cabling for high channel counts, and the large footprint that a multichannel wireless system still has – in the warehouse, on tour and backstage, both for space and the amount of time required for load-in, load-out and setup.
Sebastian Georgi and Jan Watermann are the inventors of the specific Sennheiser approach to WMAS. The technology they developed is a proprietary variant of OFDM-TDMA, specifically tailored to reliable multichannel, bidirectional, low-latency communication. They succinctly compare this wideband approach to standard narrowband technology: “Instead of many individual 200 kHz narrowband RF carrier frequencies, we use a single wideband RF channel for audio transmission – bidirectional transmission of audio and control data, to be more exact. In Sennheiser’s approach, the wideband RF channel is a TV channel of 6 or 8 MHz, depending on local regulations. The WMAS system organises its audio links within this channel. Every audio link, be it a mic or an IEM, is assigned specific time slots for transmitting its audio information – for the first time, it is possible to have IEMs and mics in the very same TV channel instead of two channels separated by a guard band. Thanks to the fact that all audio links use the full width of the RF channel when it’s ‘their turn’, RF fading is greatly reduced. It corresponds to 40-fold diversity for an 8 MHz RF channel and 30-fold diversity for a 6 MHz TV channel. Also, the spectral density is low, which makes it easier to reuse frequencies, for example on a larger festival ground, between neighbouring theatres, or in a broadcasting complex.”