SVG Tech Insight: 5 GHz Elevates Intercom Capabilities
This fall SVG will be presenting a series of White Papers covering the latest advancements and trends in sports-production technology. The full series of SVG’s Tech Insight White Papers can be found in the SVG Fall SportsTech Journal HERE.
With enhanced freedom and range, and more efficient use of the spectrum provided by digital solutions, shows are becoming more dynamic and more adventurous with deployments in increasingly complex environments such as stadiums, crowded urban areas, and in venues with architectural oddities like domed ceilings. With the number of artistic, technical, and logistics cues that are required for these action-packed endeavors, the use of digital wireless intercom has become even more essential.
As the range of uses for untethered, full-duplex communications continues to expand through more departments and production roles every day, much has been learned about the capabilities and limitations of existing digital wireless intercom technologies operating in the 1.9GHz and 2.4GHz bands. These areas of the spectrum have become packed with DECT and WiFi -based devices used for broadcast production communications, distribution, and capture — all while consumer devices continue to push for more bandwidth of their own.
Even as 1.9GHz and 2.4GHz technologies solve a multitude of problems and fulfill mission-critical roles in increasingly complex environments, the saturation of available bandwidth, constraints of legacy transmission protocols, and issues with environmental multipathing and other interference challenges have led to exploration of the possible use of the 5 GHz spectrum.
The higher frequency 5 GHz landscape opens up a multitude of possibilities for improvement. The increased radio bandwidth across its more than 25 MHz channels expands data capacity, which allows for finer control, higher capacity, more robustness, flexible transmission protocols, lower latency, and improved audio quality.
The benefits of 5 GHZ were heavily researched and tested, and input was gathered from all ends of the production field, including architecturally challenging stadium and convention center environments, indoor and outdoor live event venues, video-wall-laden conference centers, and more. Field tests at the Canadian Broadcasting Corporation (CBC), the Montreal Bell Arena, and even Times Square on New Year’s Eve are showing that 5 GHz is expanding the possibilities for digital wireless intercom technologies in particularly challenging radio environments.
Interference and Multipathing
In challenging environments like stadiums, crowded urban spaces. and in the presence of architectural oddities like domed ceilings, digital wireless intercom can suffer from interference caused by reflections. With 5 GHz, those challenges can become opportunities. Reflections, or more specifically, the multipathing they create, can be harnessed in favor of better transmission.
Through precise engineering of Orthogonal Frequency Division Multiplexing (OFDM) radio technology, the multipathing that easily propagates among 5 GHz wavelengths can be transformed into “constructive interference.” As reflections help the signal propagate, the OFDM makes the transmission more robust, helping it to survive all the extra bouncing around and deliver clear audio signal.
OFDM is also used in WiFi, but whereas WiFi’s priority is to maximize raw data throughput, the design priority for intercom is improved audio performance and the robustness of the radio link. The radio technology is application-specific, and therefore highly optimized for transmission of real time audio, where WiFi’s purpose is generic.
Multipathing can also cause limitations in propagation. So, in the field tests, engineers closely evaluated the transmission distances achieved by transceivers. In a standalone test in a large domed stadium, one transceiver covered the field and stands. In the empty stadium with no body blocking of RF, the signal went half-way up the tunnels.
In further testing during a game, four transceivers covered the stands and field for 40 beltpacks, while two transceivers were used for locker room and tunnel coverage.
Roaming / Scalability
Compared to 2.4GHz technologies, 5 GHz devices typically do have a shorter range compared to 2.4GHz. But that fact does allow for easier reuse of frequencies, which is ideal for high-density applications. In the relatively few cases where this might be an issue, intercom solutions that use the lower-frequency bands can be run simultaneously to form a single, unified communications system. Users have a lot of flexibility as they “engineer for range,” relying on a device architecture that allows for enhanced roaming across multiple transceivers, combined with deployments that maximize capabilities across spectrums.
Broadcast productions and live events have become more sophisticated, and hence more complex. This represents both technical and creative progress, and it often offers a more compelling experience for the audience, too. But it creates a challenge.
A decade ago, only the personnel who were absolutely key to a production would have access to a wireless intercom. But wireless systems have proven to be so incredibly useful that everyone, understandably, wants to have one. The issue is that it is not just production teams that use wireless; there’s a multitude of other users from security to medical staff, all of which can lead to a fog of active radio channels.
Another 5 GHz benefit for large-scale communications is that it can be managed with frequency coordination for reduced interference. Unlike DECT technologies, the 5 GHz band allow users to allocate frequencies. This Static Frequency Allocation, which is coordinated with the same methodologies as in WiFi, enables technicians to dedicate channels for intercom, camera remotes, scoreboards, and other devices, improving cooperability. The remainder of channels may then be used for WiFi. This guarantees the bandwidth required for intercom.
Field trials are showing that even in situations where there are no free 5 GHz channels, systems can still coexist with WiFi on channels without hurting its performance.
There are three additional controls and opportunities for fine-tuning made possible by the embodiment of 5 GHz technology: Coordination, power, and directionality.
Users can put their RF energy where they need it. Increased focusing capabilities allow digital wireless intercom users to narrow the likelihood they will interfere with other users operating in the same spectrum.
They can also tailor their system further through the reuse of channels when clean channels are hard to find, or to maximize capacity in scenarios where maximum range is not needed.
This means that at a major awards event, for example, where multiple 5 GHz intercoms might be used alongside various DECT-based solutions relied upon by countless outlets, it’s possible to dial back the amount of radiated power and reduce interference on neighboring systems.
Additionally, in cases where transceivers cannot be located near enough to the operators to use lower-power, and instead high power is needed, the antennas can be swapped out for directional antennas.
The enhanced audio quality that comes along with 5 GHz is due to its broad channel bandwidth, which leaves more room for audio. The result is that an intercom solution in this bandwidth can provide up to 12kHz audio bandwidth with a lower noise floor. This enhanced audio quality and lower latency is opening up new opportunities in live broadcast where, for example, mobile announcers can use pop-up voiceover booths and a wireless beltpack for clear, full speech-band audio commentary.
The characteristics of 5 GHz can only be seen as a positive for the marketplace, providing an opportunity to capitalize on new levels of performance, audio quality, and customization.
5 GHz is an excellent and future-proof choice for production environment communications.
The 5 GHz wireless spectrum is full of opportunity. It is a highly manageable resource, backed by mass market development and readily available deployment tools, that represents enormous potential for today and tomorrow.