Sennheiser has announced Spectera, the world’s first bidirectional wideband wireless solution, using WMAS (Wireless Multichannel Audio Systems) technology, to greatly reduce system complexity while considerably increasing capability. This system promises time-saving workflows and 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. It is remarkably resistant to RF fading and allows flexible use of the wideband RF channel, for example for digital IEMs with a latency down to 0.7ms.
Bidirectional digital wideband transmission addresses many of the typical challenges that users, operators and owners of wireless audio systems presently face. These 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 set-up.
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.
‘Instead of many individual 200kHz 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,’ they say. ‘In Sennheiser’s approach, the wideband RF channel is a TV channel of 6Mz or 8MHz, 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 8MHz RF channel and 30-fold diversity for a 6MHz 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.’
One of the innovations in the Spectera ecosystem is the Base Station that, in a single rack unit with 32 inputs and 32 outputs, replaces a rack-full of wireless mic receivers and IEM transmitters. An entire production could be accommodated in a single wideband RF channel (6MHz or 8MHz). The lower footprint continues to the bodypacks, which handle mic/line and IEM/IFB requirements simultaneously. ‘Having just one pack is not only a great asset for performers,’ says Bernd Neubauer, Spectera Product Management. ‘It also makes the work of the sound engineer easier, who has just one type of pack and can, if required, quickly add an IEM to a mic. Warehousing also becomes less complex, with just one Base Station and two frequency variants – UHF and 1G4 – for bodypacks and antennas.’
Via the permanent control data stream, audio settings can be adjusted, IEM and mic levels adapted, and RF health and battery status monitored. AES 256 encryption (AES 256 CTR Mode with >10kYears expiry) for both audio and control data ensures the necessary data privacy.
Also, all units help in continuously sensing the spectrum, meaning they scan for potential interference from other RF sources. With Spectera, it is possible for the first time to see ‘behind’ the RF channel that is actually being used and detect interference.
Eleven Audio Link Modes allow selectable control of audio quality, latency, channel count and operating range for each and every audio link, flexibly throughout a production. The operator can always use the RF channel to the maximum, either by giving fewer audio links a high quality or by allowing more links and reducing the quality accordingly. No matter which Audio Link Mode gets selected, Spectera offers incredibly clear sound, which ‘will be a revelation for IEM users especially’, says Neubauer. ‘With Spectera, you get stunning digital IEM clarity and accuracy with ultra-low latency. Dual Mono transmission ensures a clean separation of the in-ear channels, enhancing the sound stage for optimal performance.’
The rackmount Base Station at heart of the Spectera ecosystem handles up to 64 audio links, meaning 32 inputs and 32 outputs, in 1U-high case. One Base Station accommodates up to two RF wideband channels. The Base Station is frequency-agnostic; activation of the respective local license for the Base Station will automatically load the authorised frequency ranges.
Redundancy is key in the design of the Base Station. It features two PSUs, primary and secondary Dante connections, two slots for optional redundant Madi connections (optical or BNC) and four antenna ports, which not only allow for redundancy, but also for extended, synchronised antenna zone coverage or higher system capacity by using additional frequency ranges. The cascade ports on the unit will be activated with a future firmware release. Worth noting: There are no RF components in the Base Station, so there is no interference with other wireless equipment in the rack.
The SEKs, too, are space-savers because the very same bodypack can handle both IEM and microphone or instrument requirements, and this can be flexibly determined and changed during a show.
The bodypack features a 3-pin connector for a lavalier or headset microphone (select from a wide range of acclaimed Sennheiser models) or an instrument cable (such as the CI 1-4). The 3.5mm headphone jack connects to Sennheiser’s professional in-ear phones and features an impedance-matching high-power headphone amplifier. The SEK is fitted with a persistent display, where device information is retained on the display even when a unit has been powered down.
The bodypack is available in a UHF (470 – 608MHz and 630 – 698MHz) and a 1G4 (1350–1400MHz and 1435–1525MHz) frequency variant. It is powered by a BA 70 rechargeable battery (the same as for as Evolution Wireless Digital) and can deliver up to seven hours of operating time depending on the selected configuration.
The IP 54 protected DAD antenna is a transceiving antenna that manages mic/line signals, IEM signals, and control data at the same time. The antenna carries the RF components of the system, eliminating the need for boosters, splitters and combiners. The RF is digitized here, therefore the DAD antenna does not use a BNC connector and co-axial cable for connection to the Base Station, but a ruggedized RJ 45 connector and Cat5e cable instead, which are much easier to handle, more cost-effective, and not prone to cable losses like co-axial cables. The antenna is powered by the Base Station via PoE.
Sennheiser offers high-quality Cat5e cables with lengths of 10m, 25m and 50m. It is also possible to use Layer 1 media conversion to fibre to cover larger venues.
The new LinkDesk software desktop application runs on Mac or PC and turns it into a remote control and monitoring centre. Here, the operator can choose between the Audio Link Modes with their varying levels of audio quality, latency, possible audio links and range, as well as fully remote control, and monitor the entire system, with visibility of all audio settings and RF statuses. ‘Setting up a multichannel wireless system can be a true challenge on the software side, too. Therefore, we introduced assistive behaviours to make system management as fast and intuitive as possible,’ Benedikt Euen, Spectera Product Management, explains. ‘LinkDesk also stores productions, so operators can quickly recall their system configurations and save time at the event.’ Smart notifications offer additional assistance.
The LinkDesk software also handles the activation of the Base Station via single node-based licenses. By entering the specific local license code, the software ensures that the system operates within the local regulatory requirements for frequencies, RF channel bandwidth, and transmission power, putting operators on the safe side regarding compliance.
Spectera will evolve over time with continuous hardware, software, feature and service enhancements. On the hardware side, the next addition will be the SKM handheld transmitter. Regarding features, the implementation of the SMPTE ST 2110 family of standards for the transmission of professional media signals is planned which, in the meantime, can be achieved with Merging Technologies’ Hapi.
‘The Spectera ecosystem is a tool for the industry that will help combat the issues that have made the use of wireless so complicated until now,’ says Neubauer. ‘We will be collaborating closely with the industry on the new technology, and get valued customer input on system performance, usage scenarios and future updates.’
‘We are thrilled to see years of technological development and spectrum policy work turn into a digital wireless ecosystem that will solve many of the issues that users of wireless multichannel systems are faced with today,’ say co-CEOs Dr Andreas Sennheiser and Daniel Sennheiser. ‘Our wideband solution will be ideal for large productions, whether in the touring, broadcasting, or theatre fields, or in any other area that requires multichannel audio setups. Spectera satisfies our customers’ chief desires and needs regarding ease of use, operational reliability and flexibility. It offers less hardware, drastically reduced frequency coordination, redundancy, and the flexibility of an ecosystem that grows with your needs.’
More: www.sennheiser.com
