Sennheiser tests wireless multichannel audio WMAS system

WMAS technology Sennheiser, which takes advantage of the advantages of wireless multichannel audio systems, was tested with a pilot led by independent professional Marco Völzke and Sennheiser engineer Jonas Naesby.

The multi-channel audio wireless technology, explored by Sennheiser through WMAS, It is presented as a future alternative for highly demanding environments such as broadcast studios, theatrical productions or large musical events. To address the resilience of this system, see how it works in combination with narrowband systems and discover how it handles indirect interference, Völkze and Naesby joined forces to design a prototype that would accommodate this technology.

To carry it out, the engineers installed a system WMAS in a 8 MHz TV channel that had a system analog IEM operating at high transmit power on the lower adjacent channel frequencies, and an eight-channel EW-DX digital wireless microphone system on the upper adjacent channel. Typically, the spectrum between IEMs and microphones is not used, but is kept as a guard band. The team deliberately placed WMAS on this "no-go" channel to see if it would still work without audio interruptions.

To strain the system even further, Völzke and Naesby began to add interference in-band on the television channel used by WMAS, simulating real-life "accidents" such as an ENG crew arriving at a show with uncoordinated equipment, or a user mistakenly turning on a narrowband microphone on an old preset frequency.

Lessons and opportunities from the WMAS system

After subjecting this configuration to all types of external pressures, both engineers concluded that the WMAS system passed the coexistence check with great success. According to their findings, it worked “perfectly” when placed between a narrowband analog IEM system and a narrowband digital wireless microphone system. Furthermore, the fact that WMAS was placed in what is usually a security or guard band shows that “it can contribute to greater spectrum efficiency, allowing for much denser deployments at festivals and installations in general in various settings,” says Sennheiser.

On the other hand, when WMAS faced multiple interference sources within the band, simulating the use of frequencies not approved by third parties, the system worked “extremely well” where narrowband systems would have failed if interference occurred on their frequency. “The WMAS prototype reliably indicated the presence of these narrowband interference sources and suppressed them,” the brand notes.

Only when a fourth jammer was added directly to the WMAS channel, with the four in-band jammers placed in close proximity to each other, did a single WMAS belt fail, although the rest of the system remained stable. In cases like these, the ability of WMAS to detect interference within the band helps the frequency coordinator quickly locate and eliminate the source of interference.

More conclusions from this study can be consulted through the following white paper (English): https://en-de.sennheiser.com/newsroom/insights-into-frequency-coordination-of-broadband-wireless-multi-channel-audio-systems-wmas-and-narrowband-wireless-equipment