FCC Selling Frequency Space

February 4, 2009 by Matthew Josey 

Not too long ago the FCC sold off what is known as the 700MHz band to the highest bidder.  Technically this bandwidth is from 698MHz to 806MHz.  This will take effect on February 18 of 2009, along with the digital Television (DTV) transition.  Update: on February 5, 2009 congress passed an amendment to this pushing the DTV transition deadline back to June 12, 2009. The FCC has ruled that wireless microphones may continue to use all presently unoccupied TV channels until the end of the DTV transition.

Who bought the space and how are they planning on using it?

Commercial companies like Google, Microsoft and Dell, along with wireless cell phone carriers have purchased portions of the frequency spectrum.  These companies are primarily planning on using the space (700MHz Band) for wireless internet services.  The 700MHz band also has had large portions of it designated to Emergency Services (Police, Fire, Medical) and Homeland Security.

So what is white space?

A white space is the space between the broadcasting frequencies of TV stations.  In other words the FCC had granted analogue TV stations a range of frequencies to operate in.  After doing so, they discovered that Analogue TV stations can not operate next to each other (which is why we (in the Seattle, WA area) have channels 5, 7, 9, 11 but no 6, 8, and 10).  The white spaces are these unused TV channels (6, 8, 10 etc.)

With the changes from analogue to digital broadcasting this will also free up frequencies in the 500MHz to 700MHz ranges as well.  Digital Television has several advantages: up to six stations can broadcast in the same frequency spectrum that one analogue station can broadcast in; and DTV stations can broadcast on consecutive frequency ranges, unlike analogue TV stations; DTV Stations can be more tightly packed on the RF frequency spectrum then Analogue TV Stations.

What are white space devices?

A device intended to use the available TV channels is a white-space device (WSD) and are also now called TV Band Devices (TVBDs). (Wireless microphone systems are technically a white space device, but are not the subject of the current FCC ruling about TVBD’s (Nov. 4, 2009).)  These TVBD’s are designed to detect the presence of existing signals, such as TV stations and other wireless users, and to then avoid the use of these channels. Early ideas proposed including GPS receivers and programming each WSD with a database of all TV stations in an area, however this would not have avoided other non-stationary or unlicensed users in the area, or any stations licensed or altered after the device was made.  In a report released by the FCC on October 15, 2008 noted that these devices had met the burden of “proof of concept” in their ability to detect and avoid legacy transmissions (TV stations, wireless mics, etc.), although none of the tested devices adequately detected wireless microphone signals in the presence of a digital TV transmitter on an adjacent channel.  In November of 2008 the FCC mandated Devices must both consult an FCC-mandated database to determine which channels are available for use at a given location, and must also monitor the spectrum locally once every minute to confirm that no legacy wireless microphones, video assist devices or other emitters are present. If a single transmission is detected, the device may not transmit anywhere within the entire 6 MHz channel in which the transmission was received.

A TV Band Device (TVBD) could be a cell phone, laptop computer, or fixed point to point machinery for delivering wireless internet to homes or businesses.  In November of 2008 the FCC gave conditional support to companies to start manufacturing white space devices.  According to the FCC Nov. 4, 2008 ruling TVBD’s can not be sold prior to the DTV transition date.  So this whole process just may repeat in those frequency ranges as well.

The above information was partially sourced from Wikipedia, and from the FCC Nov. 4 2008 ruling.

Rules for TV Band Devices (TVBD’s):

  • Fixed units (for home or business install use) are allowed to operate with effective radiating power up to 4W on channels 2-51 (54MHz – 88MHz and 174MHz – 216MHz and 470MHz – 698MHz), with the exceptions of channels 3, 4, and 37.
  • Personal/Portable units (cell phones, laptops, etc.) are restricted to channels 21–51, and are also not allowed in channel 37 (reserved channel for radio astronomy and medical telemetry). They are limited to 100mW operating power or 40 mW if operating in a channel adjacent to an active TV station. This moderate power will reduce their range and therefore the possibility to cause interference.
  • Portable white space devices could include mobile phones and wireless laptop computers that are carried or worn by the user, while fixed devices could deliver wireless broadband internet service to homes and businesses.
  • Licensed operation of wireless mics takes precedence over TVBD. TVBD must coordinate around active licensed wireless mic systems.
  • TVBDs must include the ability to listen to the airwaves to sense wireless microphones (in addition to TV stations)
  • TVBDs must use location sensing in conjunction with a database of registered broadcast license assignments. The database will also include a list of protected areas for wireless microphones such as entertainment venues and sporting events. TVBDs must first access the database to obtain a list of permitted channels in the area before operating. A TVBD that lacks this capability can operate only under the direct control of a TVBD that has it.
  • TVBD’s must access the database at least once a day, and every time it changes location.
  • If the TVBD is within one Kilometer of a known wireless microphone it must change TV channels (the full 6 MHz), or stop transmitting.
  • In 13 major markets two channels between 21 and 51 will be reserved and available for wireless microphones. These will be the first open (non-TV) channels above and below channel 37. (Those 13 markets include Boston, Cleveland, Chicago, Dallas, Detroit, Huston, Los Angeles, Miami, New York, Philadelphia, Pittsburgh, San Francisco/Oakland, and Washington D.C.)

How does this effect us (wireless microphone users)?

Many wireless microphones operate in this frequency space (the in and below the 700MHz band).  As of the moment many of the microphones used in churches across the country operate in these frequencies and may run into problems.  The exact ruling on how this is going to work, still has not been rolled out by the FCC.  On Nov. 4 2008 the FCC voted to allow companies to manufacture devices that will operate in the same frequency spectrum as our microphones.  The FCC is wanting the devices to have geolocation services in them, so that they do not operate on known used frequencies in the area of the device.   This means that all area devices (wireless microphones) will need to be registered with the FCC.

  • The November 14, 2008 FCC ruling (a 130 page document) does not address the issue of wireless microphone operations in the 700 MHz band.  The FCC had proposed earlier that wireless microphone operations in the 700 MHz band should cease in February 2009, but a final transition date has not been announced.
  • Wireless microphones and personal monitors may continue to operate in the UHF television band between TV channels 14-51 (470-698 MHz), and in the VHF television band between TV channels 7-13 (174-216 MHz).
  • Even though wireless microphones would retain their licensed, secondary use status (secondary only to digital television), the white spaces proposal creates a potential for interference to wireless microphones from unlicensed devices.
  • Until the DTV transition date public safety agencies will begin to use TV channels 63 – 64 (764 – 776 MHz) and 68 – 69 (794 – 806 MHz) for two-way radio communications. As these frequencies gradually become busier, wireless microphones operating on these TV channels may encounter occasional interference.
  • After the DTV transition date, TV channels 60 – 62 (746 – 764 MHz) and 65 – 67 (776 – 794 MHz) will be opened up for use by new commercial wireless services.

Wireless microphones may continue to operate on all of these frequencies, just as they do now. However, wireless microphones that operate on frequencies above 698 MHz should not be used after DTV transition date of February 19, 2009 (Now June 12, 2009). That said, I have yet to find any rulings by the FCC saying this is an illegal frequency band to be in.  With the 700MHz band now being largely given to Emergency Services and Homeland Security, these frequencies will most likely be mobile radios.  Meaning that a frequency that works right now, just may be overridden with radio chatter when you need it most, as a cop drives by.

Users who experience interference from DTV will notice some of the following symptom’s: increased dropouts, decreased operating range, and undesired noises.  System’s which are indoors and have line of sight between transmitter and the antenna will experience better performance.

To see what DTV stations and Analog stations are operation in your area check out Shure’s Frequency finder Website.  Type in your city and state and search – Note: you do not need to select a “Wireless Series.”   Clicking the channel number will revel the frequencies of that TV channel.  Or you can check out the FCC page.

Check out this FCC Proposal saying Wireless Microphone users need to vacate the 700MHz band.  As of this time I am unaware of any ruling that brings this into law.  Therefore, wireless microphones can still be operated in the 700MHz band

How does one get on the FCC Database?

As of Nov. 2008 the FCC is still looking for someone to create and manage this database.  So since there isn’t a database yet, no one can get on it.

What are the two TV Channels set aside for my area?

That still needs to be figured out, and note that the 2 TV channels are not set aside for every market/city, just 13 major markets/city’s.

What Does the Future Hold?

  • While the current debate rotates around the 700MHz band (TV channels 52-69), the debate will surely move to the 50MHz to 700MHz ranges (TV channels 2-51).  So get ready for round 2 sometime in the future, probably right after the dust settles.
  • Google is planning on a release date of 2010 for their first full scale TVBD, based on an interview with Richard Whitt, Google’s Washington Telecom and Media Counsel on January 29, 2009.
  • White space devices are allowed to go on sale on February 18, 2009, but in reality, it will probably be much later – at least a year.  Before new devices can be marketed, they will have to pass FCC certification tests, the results of which will be open for public review and comment.  Based on this scenario, we do not expect devices to go on sale until the end of 2009.
  • In short no one seams to know.  The wireless microphone industry has stopped manufacturing wireless systems in the 700MHz band, but there isn’t actually a must stop using those currently owned units date set forth by the FCC.  Chances are, units that are currently owned can continued to be used, however expect to need to replace them soon – probably within a year or two.

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One Response to “FCC Selling Frequency Space”

  1. 700 MHz Wireless Transition : Production on November 6th, 2009 9:07 am

    [...] For a detailed explanation of that decision by the FCC please take a moment and read the “FCC Selling Frequency Space” post about it we did back in February.  This action has caused many churches and other [...]

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