From 31 December 2014, wireless microphones will no longer be able to operate in the 694-820 MHz frequency range. The restack of television services will also change channel availability below 694 MHz. Check with your wireless microphone manufacturer or supplier to find out if your mic will be effected. See below for more information from the ACMA.
Currently, a large number of wireless audio systems and devices operate within the frequency range 520-820 MHz. This frequency range is the same as that used by television broadcasting. The wireless audio systems are low power, and are allowed to operate under a Low Interference Potential Device (LIPD) class licence in the unused television channels on the basis of no interference, and no protection from interference.
Television services are currently in the process of changing over from analog to digital. This switch-over will change the ranges of frequencies that television services use, and will therefore affect the spectrum available for wireless audio equipment.
This web page provides users of wireless audio equipment with information on the analog-to-digital television changeover process and how it might affect the use of their equipment. The planning process for the digital dividend band and the replanning of digital television services are at an early stage. This page will be updated periodically as planning progresses.
Television in the UHF bands is currently broadcast on frequencies between 520MHz and 820 MHz. On 24 June 2010, the Minister for Broadband, Communications and the Digital Economy announced that by switching from analog to digital television, 126 MHz of this spectrum would be cleared in Australia. This means that after the changeover from analog to digital television, only the range 520-694 MHz will still be used for UHF television broadcasting, while the 694-820 MHz range will be made available for other services.
The block of spectrum which will be cleared through the switchover to digital television is often referred to as the “digital dividend”.
The digital dividend spectrum is able to be cleared because digital television broadcasting makes more efficient use of the spectrum than the corresponding analog services. Currently both analog and digital television services are being broadcast, with the analog services being progressively switched off on a region-by-region basis across Australia.
The diagram above shows the use of the affected part of the spectrum before and after the digital switch-over.
There are two phases to the digital television switchover that need to be completed before the digital dividend spectrum will be clear and available for other uses. The first phase is the switch-off of analog television services. This is being done on an area-by-area basis, with the final regions to be switched off by 31 December 2013.
After the switch-off is complete in each area, there will still be digital television services operating in the digital dividend frequency range. The second phase is known as the “restacking”, where the digital services will be moved so they all operate below 694 MHz. This process will also take place over a period of time on an area-by-area basis with the current target date for completion being the end of 2014.
It should be noted that due to the area-by-area switchover, it is possible that some of the areas that are ‘restacked’ earlier may be made available before the process is completed everywhere else.
The diagram below gives an example, illustrating how the use of the spectrum will change step-by-step through the switch-over process. The diagram is to illustrate the general concept only, and is not supposed to accurately represent any actual existing, or future, channel arrangement or rearrangement.
There will be two major blocks of spectrum which wireless audio equipment may be allowed and able to operate in:
The frequencies from 520-694 MHz will continue to be used for terrestrial broadcasting, and the ACMA expects that the unused TV channels or ‘white spaces’ in this range with still be available for use by wireless audio equipment, in the same way as they are at the moment.
Note that the specific arrangements of channels which will be used by digital television after the restack is still under consideration. The specific frequencies (channels) that are available in any given area at the moment may not be the same as those that will be available following the switchover.
Much of the 126 MHz of the digital dividend spectrum will be used for next generation mobile broadband services such as LTE and 4G.
Current plans provide for 2 x 45 MHz blocks of spectrum to support next new mobile broadband services. These will be separated by a 10 MHz mid-band gap and guard bands at either end.
The mid-band gap and guard bands potentially could be used for wireless audio equipment however this is subject to further studies and the outcomes of a review of the 800/900 MHz band. The guard bands and mid-band gap are currently under consideration for use to provide public safety mobile broadband capability or to accommodate services displaced as a consequence of the review.
Availability of this spectrum for wireless microphone use depends on the outcome of that review. An early indication of the possible availability of this spectrum is expected to become available in the third quarter 2013. The diagram below illustrates the spectrum arrangements in the band.
The LIPD class licence will be updated to indicate that the band 694 MHz to 820 MHz will not be available for use after 1 January 2015. However, once the results of the reviews are known the LIPD class licence will be further updated to reflect spectrum or bands that will be available for use by wireless audio equipment.
This depends mainly on what range of frequencies your equipment is able to operate over. Equipment which operates below 694 MHz should be able to operate just as it does at the moment, unless it happens to fall within a range that the digital channels get ‘restacked’ to. For devices which operate only above 694 MHz, it will depend on the final arrangements decided on for the digital dividend spectrum.
The ACMA began technical discussions with interested and affected stakeholders regarding the use of the digital dividend in 2011. The channel arrangements for digital television services in the remaining broadcasting spectrum became available at the end of 2012. Outcomes of the review of the 800/900 MHz band should be available towards the end of 2013.
The ACMA will also continue to engage with the wireless microphone industry, on an ongoing basis, throughout the planning process, particularly through industry representative groups, such as the Australian Wireless Audio Group (AWAG).
If possible, it would be advantageous to users to delay the purchase of new wireless audio equipment until the new television channel plans are finalised.
If your circumstances prevent this, the ACMA recommends the purchase of equipment that operates in the remaining broadcast spectrum 520-694 MHz with the widest possible tuning range.
The larger the range of frequencies over which a piece of equipment can operate, the more likely it will be able to find an available portion of spectrum among the parts in use.
An ‘Indicative Channel Chart’ for the restack of digital television services (‘the chart’) was issued on 21 December 2012. The chart consolidates into a single spreadsheet the detailed channel planning work that the ACMA has performed for each of the television licence areas. Although the chart is now fairly stable, definitive channel allotments will not be finalised until the relevant television licence areas plans (TLAPs) have been made; minor revisions could therefore potentially be made as a result of feedback received during consultation on the TLAPs. However the chart should, at this stage, assist in providing greater clarity to wireless audio device users on what frequencies may be available for use within the post-restack broadcasting services bands below 694 MHz.
The Indicative Channel Chart is available for download from the ACMA’s restack webpage, which can be accessed on the ACMA website.
The Minister announced on the 19 June 2012, that Broadcast Australia had been appointed to develop an indicative nationwide restack timetable, in consultation with industry and ACMA. The latest restack channel change timetable is available from the Department of Broadband Communications and Digital Economy website.
The indicative channel chart and the restack timetable should provide enough information for users to determine the availability of spectrum for use in an area.
Questions or comments for the ACMA regarding the information on wireless audio devices on this page may be sent to the ACMA’s frequency planning inbox (email@example.com).
The Australian Wireless Audio Group (AWAG) are an industry representative group for users and suppliers of wireless audio equipment in Australia. AWAG have actively provided input to the digital dividend planning process already through responses to government discussion papers and direct discussions with the ACMA. These discussions will no doubt continue throughout the planning process.
More information is available from the AWAG website.
Your equipment supplier and/or manufacturer should also be able to assist you with details of specific equipment you may own or need.
Last updated: 07 August 2013
Article from the ACMA website – http://www.acma.gov.au/theACMA/acma—wireless-microphones-and-the-digital-dividend