WMAS vs Narrowband: What's the difference - and why narrowband is still the safest choice for critical audio jobs

What are Wireless Multi-Channel Audio Systems (WMAS)?

WMAS is a system that allows many devices to share a wide range of frequencies, often simultaneously. Think of it as a huge, open highway with many lanes. Vehicles (data or voice transmissions) can spread out and use any available lane. This often involves the use of broadband technology, which consumes a larger portion of the radio frequency spectrum for each transmission.

Key features of WMAS (and broadband):

• Higher bandwidth: Each transmission uses a wider part of the frequency spectrum. This can allow for more data to be transmitted simultaneously, or for higher sound quality in some cases. Sennheiser uses 7MHz for Spectera and Shure 2Mhz for AD PSM.
• Capacity through parallelism: The idea is that with enough 'lanes' you can handle a large volume of traffic by allowing many transmissions to occur simultaneously.
• Potential for interference: With so much activity across a wide spectrum, there is a greater risk that transmissions will interfere with each other, especially in congested areas or if they are not managed efficiently.
• Spectrum efficiency: Because each transmission is 'wider', it may be less efficient in its use of the limited radio spectrum. It is like using an entire highway lane for a single cycle.
• Low transmit power per channel: WMAS is allowed to use up to 50mW of transmit power per MHz license-free which means lower transmit power per channel than narrowband.

What is Narrowband?

Narrowband, as the name suggests, focuses on using a much smaller, more concentrated portion of the radio frequency spectrum for each transmission. To return to our analogy, it's like using a precise, dedicated road - perhaps a bike lane - that is specifically designed for efficient, focused movement.

Key characteristics of Narrowband:

• Lower bandwidth: Each transmission occupies a very narrow frequency band.
• Spectrum efficiency: This is the superpower of narrowband. By being incredibly frugal with spectrum usage, it can fit many more communication channels into a given spectrum compared to broadband.
• Improved range and penetration: Because the signal is concentrated, it can often travel further and penetrate obstacles (such as buildings) more effectively. This is because the energy of the signal is focused rather than scattered.
• Robustness to interference: A narrower, more focused signal is generally less susceptible to interference from other signals, as it is less likely to overlap with them.
• Optimized for voice and critical data: Although not designed to stream high-definition video, narrowband is exceptionally well suited for clear voice communications and important data transmissions where reliability and range are of the utmost importance.

WMAS vs. Narrowband:

Let's pit them against each other:

Why narrowband often wins in critical productions

While WMAS and broadband technologies have their place, especially in consumer-oriented applications that require high data rates, it is in scenarios where reliability, range, and efficient spectrum use are imperative that narrowband consistently emerges as the superior choice.

Here's why:

1. The spectrum shortage is real: Radio spectrum is a finite and incredibly valuable resource. Governments and regulators are constantly challenged to allocate it efficiently. The ability of narrowbanding to maximize the number of channels within a given band and using only the spectrum you actually need. This means that more users can communicate without needing more spectrum. This is crucial for those productions where simultaneous, reliable transmission is vital, e.g. festivals, large events, broadcasts and the like.
2. Unrivaled reliability in difficult environments: Narrowband's range and penetration capabilities provide crucial reliability. A focused signal is simply better at penetrating obstacles and reaching distant receivers.
3. Resistance to interference: In today's increasingly wireless world, the air is crowded. Broadband signals, because they are wider, are more susceptible to picking up noise and interference from other devices. The precise nature of narrowband makes it significantly more resilient, ensuring clear and uninterrupted communications when it matters most.
4. Cost-effectiveness for critical infrastructure: Narrowband's efficiency often means less complex infrastructure to achieve reliable coverage, leading to significant cost savings.