With the digital dividend spectrum auction finalised and spaces allocated to the major telcos, what does this mean for users of wireless microphones and in-ear monitor systems? Callum Fitzpatrick reports.

From 1 January 2015, frequencies between 694MHz and 820MHz (known as the digital dividend) will be reallocated to mobile voice and data applications. As such, this band will no longer be available for wireless microphones or in-ear monitor systems and it will be illegal for these devices to operate in this range.

Instead, any wireless audio transmitters have to function between 520MHz and 694MHz, and must share the space with TV broadcast stations. If equipment doesn’t operate within this range, it must be replaced, or if possible, retuned to transmit in the new band. It is estimated that around 150,000 wireless audio units will be required to vacate their current space to provide “clean and unhindered” access for the new users of the spectrum.

To complicate matters further, the frequencies available to users will vary depending on their location and proximity to TV transmitters.

Sennheiser manufatures a wide range of microphones, headphones, headsets and communication devices, so its customers have inevitably been heavily impacted by the changes. As a result, Sennheiser Australia recently introduced www.frequencyfinder.com.au, a website which allows users to input their location and find out which frequencies are available to them.

“This is important as it shows the industry what the landscape will be in 2015 and it enables professionals to be responsible in future-proofing any equipment they install,” says Sennheiser Australia manager professional division Chris Smith.

“We’re in an exciting time of technology where communications such as 4G, digital TV and wireless technologies are available to us nearly everywhere. The problem is, the more we demand this content, the more spectrum is required to broadcast it properly.”

With the changeover to digital TV still underway across Australia, a significant amount of spectrum is required to cater for both analogue and digital signals. When all analogue transmissions have been turned off, the digital information will fit into a much smaller space.

The Australian Communication and Media Authority (ACMA) is the body which oversees spectrum management and it will organise the restack of all TV channels when analogue ceases to operate. This will essentially pull everything out of the 694MHz to 820MHz band to make space for the telcos.

These changes can potentially cost customers thousands of dollars if they are required to replace their old equipment. Nevertheless, Chris says that this could still be a cheaper option than if all consumers were required to purchase a licence to use equipment.

“Radio frequency (RF) spectrum is a finite resource that is worth a lot of money to the government. The bottom line is, we’re a secondary user and we operate under a class licence,” Chris says.

“The restacking is an ongoing process, so some users may find that their gear works until the end of 2014, whereas others may find that theirs has already stopped working.”

Jeff MacKenzie, the technical resource group manager at Jands, a distributor of Shure wireless audio products, adds that users may also find that using their microphones may even cause them to interfere with local TV stations.

“It’s likely that people in high density city areas will be hit the hardest. That’s where a lot of these new communications will be launched first. People in rural areas might not notice any change for some time,” Jeff says.

“If a user is in close proximity to a TV station sharing the same frequency, they will most likely experience some serious interference.

“Likewise, you may even cause interference to the new services. Until the rollout happens, we won’t really know for sure.”

Chris adds that although many installers and broadcasting professionals are abreast of the implications of the digital dividend, awareness needs to be raised for the general public.

“The government should be implementing a better education campaign. We’re promoting our website to our end users and resellers, but there are a lot of schools, churches, gyms and venues that might’ve been using the same system for 10 years. They may find that their equipment simply stops working. It’s a matter of getting the word out to all those people so they can make an informed decision about their equipment,” Chris says.

The worry is that without the correct education, many of these ‘plug-and-play’ users will unknowingly become criminals if they carry on as normal.

That’s why the Australian Wireless Audio Group (AWAG) has created a petition to be presented to the president of the National Senate. It says that unless something is done urgently, the changeover will be a significant public policy failure as users become criminals under the 1992 Radiocommunications Act.

The petition asks that the Senate ensures that the government urgently develops a comprehensive, well-resourced transition plan that includes communication, education and compensation for those wireless audio users impacted by the spectrum change.

“We’ve been trying very hard to reach out to end users as much as we can,” Jeff says.

“The problem is, because wireless microphones come under a ‘class licence’, nobody has to fill out any documentation to own one, so there are no central records of who the users are.

“We are trying to communicate with them through various industry associations, as well as education associations and churches. However, we’ve had less success than we would have liked. Even if AWAG took out a billboard telling users they can no longer use certain frequencies, the average consumer isn’t going to know what that means.”

Chris adds that the government should also be cracking down on people selling out-of-frequency wireless microphone systems.

“At this point in time, you can be sold a system that will be illegal post 2014 and there will be no recompense to you. We see this as a major issue – it should be illegal to sell these,” he says.

Jeff notes that the wireless audio industry isn’t looking for any drastic changes, it just wants fair treatment from the government.

“The digital dividend is a worldwide trend – it’s not unique to Australia. The changeover from analogue to digital TV means they can deliver the same amount of content using less spectrum. It makes sense that regulators around the world have used this as an opportunity to free up space to sell elsewhere.

“But they seem to be forgetting that we’re losing around a third of the spectrum that we had and we’re having to bunch up with the remaining television transmitters. It’s not going to be easy.

“We’re not asking them not to go ahead with the restack – we realise that there are some massive benefits to the greater community. But if people have to throw their systems in the bin, they should be compensated in some way.”

To find out if this will be your fate, Jands has made the Shure Frequency Calculator available at www.readyfordigital.com.aul which calculates the signal strength of TV transmitters within a set radius of your location, using proximity and output power of local transmitters as its guide.

However, spectrum availability can vary vastly depending on your location.

“Gold Coast is probably one of the worst RF environments in Australia for wireless microphones at the moment,” Chris says.

“You have the local TV transmitters, as well as some which are operating inland to the west. You also have signals coming down from Brisbane and up from New South Wales. That takes up almost all the spectrum there is.

“It’s going to be tough for AV integrators, touring companies and professional hiring businesses to make sure they’re sending out systems they know will operate. It really is a fine line, but with a bit of forward-planning, it should be a breeze.”

Although most devices don’t currently operate in the range, the 1790-1800MHz frequency band has now been reserved exclusively for audio transmission across Australia. Sennheiser has launched a range of wireless microphone systems that transmit on 1800MHz, so users don’t have to plan their systems around primary users or search for gaps between TV channels.