Exploring WMAS: The Future of RF Wireless Microphone Technology

You may have heard the term WMAS (Wireless Multichannel Audio Systems) and wondered what it means. WMAS represents the next generation of RF (Radio Frequency) wireless technology, offering advantages like more audio channels within the same RF spectrum compared to current narrowband devices, as well as easier deployment. This increased channel capacity also simplifies frequency coordination because there are fewer frequencies to manage. Professional users who routinely deploy wireless microphones and in-ear monitors (IEM) for live sound, theater, broadcast, houses of worship, and location sound will appreciate these advancements in wireless technology.

Recently, both the FCC (Federal Communications Commission) and CEPT (the European regulatory body) have adopted regulatory changes that permit wireless microphone systems to use spectrum blocks wider than 200 KHz, provided the equipment uses the spectrum efficiently. With these wider blocks, multiple audio channels can now share the same frequency, allowing a single frequency to operate multiple wireless channels. This capability is reflected in the terms "Multichannel Audio" in “WMAS.”

Narrowband UHF wireless microphones are regulated to operate within a spectral mask of no more than 200 KHz per RF carrier. While narrowband RF wireless devices can use less than 200 KHz, they cannot exceed this limit. Leveraging our technical expertise, Shure has delivered narrowband products that maximize the use of this 200 KHz limit, providing reliable, high-fidelity solutions.

The width of a WMAS block used depends on the design of the system, the number of audio channels needed, and regulations. WMAS systems will operate in blocks wider than 200 KHz. As WMAS products become available in the market, Shure is committed to providing responsible, reliable, and scalable WMAS RF solutions. Equipment that uses large amounts of spectrum when only a low channel count is needed makes it challenging for other RF users to coordinate their wireless microphones. To avoid this, WMAS regulatory rules require that these new systems be capable of efficient spectrum use.

WMAS is not a standardized method of transmitting audio wirelessly; it can vary significantly from one system to another and even within the same system if multiple transmission modes are available. Each mode of transmission has its own benefits and constraints. Differences include how interference is managed, the number of audio channels possible, and the overall range and reliability of each implementation. WMAS primarily reflects the new rules that permit the use of wider spectrum blocks. How these wider blocks are used depends on the manufacturer. One thing is for certain: these wider spectrum blocks offer new possibilities and features not available with traditional narrowband wireless devices.

WMAS rules introduce new and exciting features not seen before in wireless systems. While these features are highly anticipated, WMAS will not immediately replace current narrowband wireless systems. Introducing WMAS presents a new opportunity for efficient spectrum use. WMAS achieves this by minimizing the minimum channel spacing between adjacent audio channels and strategically locating the resulting intermodulation products (IMDs) within their own radio channel, situated on the left and right edges (as shown in Figure 1). This is made possible by employing a broadband multi-carrier transmission method that combines several audio channels into a broader radio channel.

As a trusted thought leader, Shure has advocated for higher output power in WMAS systems to ensure reliable operation. In the U.S., Shure's Spectrum & Regulatory Affairs team petitioned the FCC to allow higher output power for WMAS compared to narrowband systems, and we are pleased that the FCC accepted our recommendation. The higher power allows WMAS to provide equivalent link performance as narrowband systems. In particular, the FCC allowed unlicensed use of WMAS at a higher power of 100 mW EIRP compared to legacy devices. The FCC also allowed WMAS to operate on a licensed basis at the same power levels currently permitted for narrowband devices (for example, 250 milliwatts conducted power in the UHF band).

In summary, the future will bring new WMAS wireless systems that are set to fully leverage the recent changes in regulatory rules. These advancements will enable more efficient use of the RF spectrum, allowing for a higher density of audio channels within the same bandwidth. This increase in efficiency will not only enhance the quality and reliability of wireless audio but also simplify the coordination and management of multiple wireless devices. As these WMAS systems are rolled out, users can expect a host of benefits, including easier setup and improved overall performance. Shure is committed to staying at the forefront of this technological evolution, ensuring that our products meet the highest standards of innovation and reliability. With these new WMAS wireless systems, the future of wireless audio looks brighter than ever.