RF Spectrum Reallocation Information Bulletin

From SennheiserUSA:
Wireless microphones primarily operate on frequencies in the UHF TV spectrum. 

Changes in technology and national policy will affect wireless microphone operation in the future. Click here for a summary of the current status. 

The United States is in the midst of a transition from traditional analogue television broadcast to digital TV (DTV). Currently, networks are broadcasting both analogue and digital signals on separate channels simultaneously. It is planned that by February 17, 2009 the analogue channels will be turned off freeing up the channels they are currently occupying. At that time, the Federal Communications Commission (FCC) will reallocate channels 52-69 (698 – 806 MHz) for new services such as public safety communications and auction to the private sector. This is termed the "digital dividend". 

In addition, the FCC is considering proposals to allow unlicensed wireless devices to operate in channels 2-51 that are not occupied by local TV stations. These include broadband services, PDA's, cell phones, home networking devices and other consumer electronics. These unoccupied local TV channels are being called "white spaces". If such legislation is enacted, these devices will be new potential sources of interference for wireless microphones, intercoms, and monitoring systems. 

The proposed date to allow unlicensed devices to use the spectrum is also February 17, 2009. However, in an effort to bring broadband to underserved areas quicker, Massachusetts Senator John Kerry has introduced the Wireless Innovation Act of 2007 (S. 234) that would shorten the timeline to within 180 days of enactment. A version of this bill has also been introduced in the House of Representatives (H.R. 1597) by Representative Jay Inslee of Washington. 

Separately, New Hampshire Senator John Sununu has introduced the White Spaces Act of 2007 (S. 337). It would open white spaces within 90 days of passage, or by October 1, whichever comes first. This bill also considers the option of auctioning licenses for the spectrum. 

Conversely, Congressman Bobby Rush of Illinois has introduced The Interference Protection for Existing Television Band Devices Act of 2007 (H.R. 1320). It would require manufacturers of unlicensed devices to demonstrate that their product will not interfere with existing devices, such as wireless mics and monitoring systems. It also calls to cease deployment of fixed wireless devices, such as broadband services to rural areas, until after the digital television changeover is complete. The bill suggests that new portable devices would be allowed to use white spaces after fixed devices have been operating for three years without causing interference. 

The FCC and industry leaders have stated that adequate time must be allowed to develop solutions that will permit unlicensed devices to operate without causing harmful interference to current users of the TV spectrum, including wireless microphones. 
  • There are some proposed solutions and compromises to allow co-existence. These include:Listen Before Talk
  • This proposed technique relies on the unlicensed devices to check for existing RF-traffic before transmitting.
  • Geolocation/Database
  • Location sensing and consultation with a database of broadcast license assignments (use of GPS receiver). It would require entering requests for frequency/spectrum reservation into the 'consulted' database by any potential user.
  • Local Beacon
  • Reception of a locally transmitted signal that identifies which TV channels may be used in the local area for unlicensed use. It would require entry of used frequencies/spectrum to be entered into (and removed from) the data stream to be transmitted by the beacon.
Each of these solutions has merit. White space legislation and these proposed solutions are likely to be subjected to long debate and go through several revisions before any bill is enacted. We will continue to keep you posted on any major developments. 

In the meantime, feel free to contact us or visit our web site for the latest guidance on frequency selection in your area. Thank you. 

For more information, contact:
Joe Ciaudelli
Sennheiser Electronic Corporation
1 Enterprise Drive
Old Lyme, CT 06371
Phone: (860) 434-9190