Are you sure your
Wireless Microphone and In Ear Monitor systems
will still work after the 1st of January 2015?

The Impact

• What is the Impact?

  The UHF spectrum available for Wireless Microphones and In Ear Monitor systems will be more congested and all users will have to share the range between 520 MHz and 694 MHz with the Digital TV stations. Because the frequencies of the TV transmitters will also change, even some existing wireless systems operating between 520 MHz and 694 MHz may no longer work without interference or be legal, depending where they are being used.

• What is the Impact?

  What are the uses of the UHF band today?

  The current primary use of the UHF band between 520 MHz and 820 MHz is for Free to Air Television broadcasting in analogue and digital (FreeTV). Wireless Microphones and In Ear Monitor systems also use this band, sharing it with the TV broadcasters. The TV broadcasters have priority use of these frequencies. Users of Wireless Microphones and In Ear Monitor systems are secondary users, conditional on them not interfering with the reception of Free to Air TV broadcasts.

  Will frequency changes continue in the UHF band?

  Yes, until the end of 2014. Digital Free to Air TV broadcasts began in Australia in 2009. Since 2010, analogue TV transmitters are being switched off gradually in different regions, the aim being to have all analogue TV transmitters turned off by the end of 2013. The ultimate goal is to deploy 6 Digital TV channels in each TV service area across Australia by the end of 2014. These 6 channels will all be on adjacent frequencies in a TV service area. Each channel will occupy 7 MHz of bandwidth, so these 6 channels will occupy a block of frequencies 42 MHz wide. (6 channels of 7 MHz each).

  What are the new uses of the UHF band after the 1st of January, 2015?

  The end of analogue Free to Air TV broadcasting, the introduction of Digital Free to Air TV and the re-stack of the TV frequencies has freed a frequency range between 694 MHz and 820 MHz. This range of frequencies is known as the Digital Dividend. From the 1st of January 2015, across Australia, this band will be assigned for the deployment of mobile voice and data services. Two frequency bands are used: 703 MHz to 748 MHz and 758 MHz to 803 MHz. The 10 MHz space between these two blocks is called "The Mid-Band Gap".

• What is the Impact?

  What are the legal requirements for the use of wireless microphones in the UHF band?

  In Australia Wireless Microphones and In Ear Monitor systems currently operate under what is called a Class Licence as a Low Interference Potential Device (LIPD). Within this Class Licence, Wireless Microphones and In Ear Monitor systems operate under Item 22A. There are some conditions that apply under Item 22A, including maximum power of 100mW, maximum bandwidth of 330KHz, you cannot transmit on the same frequency as a TV transmitter licenced for that area and if you transmit on a frequency adjacent to a TV transmitter licenced in that area you must be at least 400 KHz away from the upper and lower edges of that TV transmitter frequency range.

  As at July 2012 the law had not changed in relation to the Class Licence for LIPDs. It is expected though, that Item 22A will change to reflect the narrower frequency band available (520 MHz to 694 MHz) and make operation in the frequencies of the Digital Dividend (694 MHz to 820 MHz) illegal. It is also likely to reflect some technology changes as digital techniques start to be deployed more widely in Wireless Microphones and In Ear Monitor systems. It is possible that operation within the Mid-Band Gap (748 MHz to 758 MHz) may be allowed, however it is likely that this area will be less reliable than the frequencies between 520 MHz and 694 MHz.

• What should we use?

  So how do you choose a wireless microphone in the range from 520 to 694 MHz?

  You must select a system which can operate on frequencies that are not used for Free to Air TV broadcasts in the location where the Wireless Microphones and In Ear Monitor systems will operate. Wireless Microphones and In Ear Monitor systems transmit very low power which can be interfered with by a television transmitter which is much more powerful. Also, because Wireless Microphones and In Ear Monitor systems are secondary users they should not in any way interfere with television reception.

  The range of Sennheiser products includes models that are compatible with the frequencies that will be available in different areas across Australia.

  The following range will be used for Wireless Microphones and In Ear Monitor systems:

  • The UHF range from 520 MHz to 694 MHz shared with Free to Air TV broadcasting.