Congress directed the FCC to create a National Broadband Plan that increases the bandwidth available for broadband Internet access. The Plan is very broad, covering both wired broadband and the spectrum from 225 MHz-3.7 GHz (though only some of those frequencies are subject to reallocation). The primary focus of this page is the UHF TV bands (channels 14-51, corresponding to 470 MHz-698 MHz as defined under 47 C.F.R. §73.603(a)). The UHF TV bands are arguably the most valuable part of the spectrum and the ongoing changes made possible by the DTV transition are also probably the most visible changes to the spectrum.
Readers who attended the "Changing Channels: How New FCC Regulations for Wireless Microphones and Wireless Broadband Affect (Almost) Everyone" program sponsored by the Micrographics/AudioVisual Special Interest Section at the 2010 American Association of Law Libraries Annual Meeting can find those materials immediately below. Readers who did not attend can skip that section and proceed to the sections containing the most recent information unless they have a specific interest in the spectrum management policy issues discussed by Professor Bernthal.
Readers new to the issues should start with the overview section and read each section in order.
Thanks to Laura Ray for helping with the tickets and the signage on the day of the program. Thanks to Terry McCormack and Professor Brad Bernthal for speaking on our program and helping to make the program a great success.
Ryan recorded a presentation after returning from the Annual Meeting because the PowerPoint is not a standalone document. The capture software did some odd things to the PowerPoint, but did not materially affect the viewability. The capture software offers an audio only screen reader version when you click on the link.
TV broadcasters are the primary users of TV channels in most markets, though public safety organizations can be primary users of TV channels 14-20 in thirteen TV markets specified by 47 C.F.R. §90.303. Secondary users may operate only if they do not cause interference to primary users (e.g., 47 C.F.R. §74.803(b)). In the TV bands this means operating on vacant TV channels, though TV broadcasters are prohibited from operating on channel 37 under 47 C.F.R. §73.603(c). Medical telemetry, radio astronomy (both of which operate on channel 37 under 47 C.F.R. §73.603(c) and 47 C.F.R. §95.1101) and wireless microphones are incumbent secondary uses. Wireless microphones may operate on any vacant TV channel below channel 52 under 47 C.F.R. §74.802(c) as modified by the Wireless Microphone Report and Order (the rule modification is found in Appendix B on page 71). As will be discussed in more detail in the next section, some channels are more desirable than others. There are no professional wireless microphone systems on the market operating below channel 14.
Broadband access using vacant TV channels (a.k.a. "white spaces") can be either licensed or unlicensed spectrum. Spectrum can be licensed on either an exclusive or non-exclusive basis. The DTV transition included the removal of the TV broadcasters from TV channels 52-69 (referred to as "the 700 MHz band" though the actual range is 698 MHz-806 MHz). The new 700 MHz licensees (primarily cell phone companies or public safety organizations) have exclusive use of their licensed bandwidth. Customers of companies such as AT&T or Verizon may be using channels 52-69 when they access the Internet using the 4G networks on their cell phones.
The White Spaces Second Memorandum Opinion and Order finalized the regulations for the Television Band Devices (TVBDs) which will operate on an unlicensed basis secondary to TV stations. TVBDs may not come on the market for another 12 to 18 months, but the FCC already contemplates removing TV broadcasters from twenty additional TV channels as part of the National Broadband Plan, a change to be implemented in 2015.
The FCC references the Plan in the White Spaces Second MO&O and strongly hints that these channels are going to be auctioned for the exclusive use of licensees. If this occurrs, more than half of the authorized channels for portable TVBDs will disappear within three years after the introduction of the devices. The Commission actually suggests in paragraph 133 of the White Spaces Second MO&O that manfacturers engineer TVBDs to operate on channels it does not currently authorize. If manufacturers did so, they would simultaneously be expected to ensure that users would only use currently authorized channels. Obviously, this has the potential of decreasing the manufacture and sales of TVBDs, but TVBD manufacturers have made little noise so far.
TVBD manufacturers are promoting TVBDs as providing low cost high speed broadband Internet access. If true, TVBDs are likely to be beneficial to anyone who needs to improve broadband access while reducing costs. While wireless microphones are not as widely used as broadband Internet access, those who do use wireless microphones depend on them. The remaining sections discuss various regulations and scenarios confronting users who hope to make use of both TVBDs and wireless microphones.
The FCC issued the White Spaces Second Memorandum Opinion and Order on September 23rd, 2010. It makes substantial modifications to the previously existing regulations. The most significant of these changes for users of wireless microphones is the elimination of the spectrum sensing requirement. Readers should consult Appendix B on pages 60-74 of the Order in conjunction with the C.F.R. to read the currently applicable regulations.
Portable TVBDs may operate on vacant TV channels from 21-51, excluding channel 37 and channels reserved for wireless microphones [47 C.F.R. §15.707(a), page 63].
Fixed TVBDs may operate on vacant TV channels from 2-51 excluding channel 37 and channels reserved for wireless microphones [47 C.F.R. §15.707(a) and §15.707(b), page 63], but are subject to additional interference protection requirements [47 C.F.R. §15.712(a)(2) and §15.712(d), page 68] that reduce the number of available channels because of the higher power at which fixed TVBDs are authorized to operate [47 C.F.R. §15.709(a)(1), page 63].
A particular TV channel is considered vacant for portable TVBDs if the portable TVBD is located at least 6 km outside of the nearest TV station protected broadcast contour on that channel [47 C.F.R. §15.712(a)(2), page 68]. This is what the FCC refers to as a "co-channel" regulation.
While the available channel range for a portable TVBD is yet to be determined, it is likely to be at least across the entire range of authorized TV channels for the reasons mentioned in the overview.
The spectrum sensing requirement previously in the rules would have prohibited a TVBD from operating on any part of a TV channel if the TVBD detected a wireless microphone signal on any part of that channel. It would also have required a TVBD to vacate an entire TV channel upon detection of a wireless microphone signal in any part of that channel. The elimination of the spectrum sensing requirement will allow a TVBD signal and a wireless microphone signal to occupy the same frequency at the same time.
A wireless microphone transmitter operates over 25 kHz-200 kHz at any given time. The operating range of a TVBD is as yet unknown. The FCC implemented power spectral density limits for TVBDs [47 C.F.R. §15.709(a)(5), page 64] that allow TVBDs to reach maximum power allowed under the regulations only if operating over an entire 6 MHZ TV channel. The regulations contemplate the possibility a TVBD might operate in multiple TV channels at one time.
Wireless microphone manufacturers do not provide sufficient technical detail about the operation of microphone squelch controls to determine whether any TVBD signal can be suppressed (using maximum squelch would severely reduce the microphone transmitter's range). Nor is it clear how many TVBDs will be able to simultaneously occupy a TV channel. There is a distinct possibility that TVBD signals will interfere with wireless microphone operation. If so, wireless microphones will operate reliably free of interference only on the reserved channels.
The first vacant TV channel above and below channel 37 is reserved for wireless microphones nationwide [47 C.F.R. §15.707(a), page 63] (the co-channel requirements that define channel vacancy may be different for wireless microphones and are covered in the next section). For the University of Toledo College of Law in Toledo, Ohio, these channels are 36 and 39. Channel 38 is occupied by a low-power TV station whose protected broadcast contour includes the University of Toledo campus.
Although fixed TVBDs operate on channel 14-20, they are prohibited from operating adjacent to occupied TV channels [47 C.F.R. §15.712(a)(2), page 68]. In markets where public safety does not use 14-20, wireless microphones would have protected operation from portable TVBDs on any vacant channel from 14-20 and from all TVBDs if the vacant channel in that range is adjacent to an occupied channel. For Toledo Law, these channels would be 14 and 15 protected only from portable TVBDs and 16, 18, and 20 protected from all TVBDs. However, this would be true only if the FCC harmonizes the co-channel requirements for wireless microphones with the co-channel requirements for portable TVBDs.
On January 22nd, 2010 the FCC issued its Wireless Microphone Final Report and Order regarding the removal of wireless microphones from the 700 MHz band (TV channels 52-69). The Commission has granted temporary authorization to all wireless microphone users in other channels, but authorization for wireless microphone usage in 700 MHz ceased on June 12th , 2010. If readers think they still own 700 MHz microphones, they can check to see if their microphones operate on those channels (with corresponding frequency numbers between 698 MHz-806 MHz).
The Commission issued a Further Notice of Proposed Rulemaking focusing on the question of how much regulatory protection wireless microphones will receive from TVBDs, but it has answered most of those questions in the White Spaces Second Memorandum and Order. While it is theoretically possible the Commission could still license a substantial number of new users, it probably telegraphed its intentions by modifying the TV bands database requirements [47 C.F.R. §15.713(h)(8), page 72] to allow large users such as Broadway theaters access to the TV bands database without requiring those users to be licensed.
The FCC also stated in paragraph 31 of the White Spaces Second MO&O "We observe that there are a wide variety of applications for wireless microphones ranging from a single wireless microphone used by a performer or presenter, to small theatrical productions using perhaps 10 - 20 microphones, to large scale productions and events such as professional sports events and Broadway style productions that may use well over 100 wireless microphones. The overwhelming majority of such use does not merit registration in the TV bands database."
It is virtually certain that most readers' institutions will not qualify for licensing. It is likely that the FCC will prohibit unlicensed microphone use on channels 14-20 in markets where public safety uses those channels.
The primary remaining part 74 issue of interest to wireless microphone users is the wireless microphone co-channel requirements. The current co-channel requirements in 47 C.F.R. §74.802(b)(3) require 70 miles (113 km) distance from the broadcast station itself. This is significantly more protective of the television stations then the portable TVBD co-channel requirements. At Toledo Law, no channel from 14-20 would be considered a vacant TV channel.
Because most wireless microphones operate at a lower power than authorized for portable TVBDs, it would make sense for the FCC to harmonize the co-channel regulations. However, this outcome is far from certain. The TVBDs would be engineered to avoid co-channel interference by automatically consulting the TV bands database [47 C.F.R. §15.711(b), page 64-65]. Wireless microphones would depend on human compliance with regulations. Unfortunately, the wireless microphone final rules are not on the agenda for the October 14th, 2010 FCC meeting and the answer will not be known in the near future.
The National Broadband Plan contemplates reallocating 500 MHz of UHF spectrum to broadband use including 120 MHz (twenty 6 MHz TV channels) from the TV bands. The TV bands reallocation would be implemented by 2015 (see e.g., the page 1 chart of the Broadband Action Agenda). President Obama endorsed that goal with the Presidential Memorandum: Unleashing the Wireless Broadband Revolution.
M/AV-SIS has proposed a program on broadband deployment for the 2011 AALL Annual Meeting. Faster Than a Speeding Turtle: the Promise and Challenges Of National Broadband Deployment will discuss the difficulties of the potential spectrum reallocation, including its potential impact on TVBDs as a robust means of broadband deployment. The program would also show attendees some tools they can use to test and evaluate their own broadband needs and speeds.
This section assumes that the reader owns wireless microphones and is seeking to apply the new regulations to their operation.
The FCC's assertion in paragraph 29 of the White Spaces Second MO&O that its channel reservations ensure "a significant amount of spectrum will be available on which wireless microphones can be operated as they have in the past" is highly misleading as applied to individual institutions or users. Most users will be limited to a single reserved channel that may or may not accommodate a sufficient number of microphones if they are operating in reserved channels at all.
One of the drawbacks with current professional wireless microphone systems is that most systems operate over seven TV channels or less. Only a few high-end systems offer more than seven channels in a channel range. Only one very high-end system includes channels above and below channel 37 in the same channel range. Even that system does not offer channels 14-20 in the same range. Channel 37 is an obvious dividing line for channel ranges. Only very large users will be using a sufficient number of channel ranges to encompass both the first vacant channel above and the first vacant channel below channel 37. Only very large users will be using a sufficient number of channel ranges to encompass a vacant channel adjacent to channel 37 while simultaneously operating microphones in channels 14-20. This is partly due to the risk of intermodulation interference.
Intermodulation interference also limits the number of microphones that can be placed in a particular TV channel. Most professional wireless microphone systems allow between three and eight microphones per TV channel. Some systems allow eight microphones only in one of the channels within the channel range. The average number of microphones per channel can be much less than eight even when one or more channels within the range support eight microphones. Building walls can attenuate broadcast TV signals, but signal attenuation is an unreliable means of avoiding interference on channels within protected broadcast contours unless the building was built specifically for signal attenuation. These technological limitations give increased importance to properly identifying the channels in which your microphone system operates and verifying whether or not these channels are reserved.
If you are like most wireless microphone users, you purchased your microphones from a vendor rather than directly from microphone manufacturer. At least in the church and educational markets (and presumably any market for similarly sized users), vendors encourage users to rely on them in making appropriate channel range choices. Unfortunately, two examples suggest this reliance can be misplaced. First, when the University of Toledo College of Law purchased microphones from a local vendor in 2003, the vendor chose a channel range in which two of the four full TV channels in the selected range had already been auctioned off by the FCC. One of the those channels became unusable within months of purchase. Second, when the FCC issued its Wireless Microphone Further Notice of Proposed Rulemaking in January 2010, it proposed new record-keeping regulations applicable to both manufacturers and vendors that would raise the cost of doing business. Twenty-two vendors filed comments; only one even acknowledged the new regulations.
Nor is manufacturer information reliable. One vendor I talked to at a AALL Annual Meeting recommended using the Shure frequency finder which can provide a list of TV channels within a specified radius of your zip code. When tested for Toledo, Ohio, the frequency finder was both out of date and incomplete. It was out of date because the list failed to include recent changes that added two channels occupied by full power TV stations to the list of channels to avoid. It was incomplete because it includes only full power TV stations. The University of Toledo College of Law is within the protected broadcast contour of five low power or class A TV stations.
The first step in applying the regulations is to determine your current TV channels of operation. Some microphone systems include both the TV channel number and the frequency number, others include only the frequency. The manufacturer's manual should at least list the frequency ranges. Many manuals also have charts defining how many microphones can go into each TV channel. The chart at 47 C.F.R. §73.603(a) lists the 6 MHz frequency for each channel from 2-69 if you need to convert that range into its corresponding TV channels to determine your operating channels and/or to create your own chart.
The second step is to determine whether the channels on which your wireless microphones operate are reserved for wireless microphones in your market. The FCC provides a TV Query Database to identify TV stations in your area. If your institution runs wireless microphones in a single building, you can use Google Earth or a GPS to identify the latitude and longitude of your location. Multiple buildings might require mapping multiple locations.
Determining which TV stations are vacant can be as simple as glancing at the list and noting the numbers that are not there. You may want to copy the information into a spreadsheet for record-keeping.
It may turn out, however, that under the current wireless microphone co-channel requirements there are no vacant TV channels. If you are faced with this situation, you may want to take the next step and determine the nearest channel not inside or near a protected broadcast contour. This would show you both the channels off-limits to TVBDs and any additional vacant channels that might become available if the FCC harmonizes the co-channel requirements.
Determining whether you are inside the broadcast contour is more time-consuming, because you will have to click on each list item individually. Any broadcast contour that was mapped before May 27th, 2010 can be found by clicking a link titled "Service Contour Map (xx dBu)" for each broadcast station. If a station operates on two channels or has two different listings for the same channel, there could be two different maps.
Even if your wireless microphone systems operate in a reserved channel or channels, you may also need to operate in unreserved channels.
You could turn up the microphone squelch in an attempt to suppress the TVBD signal or signals. As mentioned above, it is not clear whether this will work at all, much less allow you the range you need on your microphones. You could implement the airline rule of requiring people to turn off their devices. However, it is not clear how wide the radius must be in order to avoid interfering signals. Turning off the devices in the same room as an event is much simpler than turning them off in the entire building. Because the regulations require TVBDs to display channel information (47 C.F.R. §15.711(c), page 66), TVBDs may incorporate the ability to manually change channels. You could also attempt to implement and enforce rules within a building regarding the allowed channels of operation for TVBDs.
If your institution is contemplating buying new wireless microphones in order to access reserved channels or to identify the maximum number of vacant channels, you could create a spreadsheet entry for the nearest TV station in each channel. Channels not listed at all within the 113 km radius could be listed as vacant. Even small markets might have 50 entries to sift through. Larger markets might have more than 100. However, taking the time to do this would enable you to make an informed decision regarding which manufacturer, model, and channel range best meets your needs.
Any user or institution purchasing microphone systems in the next few years runs the risk that the FCC will take away the systems' operating channels in 2015 when it implements the next TV channel reallocation.
While readers and their institutions are likely to benefit from TVBDs, too little information is known to describe what to look for when making a TVBD purchase. The only obvious recommendation right now is to manually choose the channels of any TVBD used to avoid conflicts with wireless microphones.
The FCC seems to be envisioning portable TVBDs as handheld Internet access only devices, but the manufacturers have not confirmed this. UHF TV band transmitters could easily be incorporated in low-end laptops and cell phones. Manufacturers have little incentive to disclose any details to potential competitors.
As mentioned in the overview, TVBDs are probably at least a year away from hitting the market with a channel reallocation occurring in less than five years. However, the Notice of Proposed Rulemaking for the next TV bands reallocation is scheduled to be released by the end of this year, with the Order being released in 2011 (see e.g., the page 1 chart of the Broadband Action Agenda). It is likely that much more information about both reallocation and TVBDs will be available within six months.
M/AV-SIS will continue to monitor the situation and provide new information as it becomes available.
The FCC's Electronic Comment Filing System web site
This is the FCC's web site for filing comments electronically, or searching for filed comments. The easiest way to find the most recent filings is to click on the "search for proceedings" link (the second one on the page) and enter the docket number. Searching for proceedings creates separate results lists for FCC and party filings. If you want to run a more comprehensive search you can click on the "search for filings" link (the first one on the page) and add or remove the appropriate search terms or restrictions.
Please note, most of the links below are in PDF format. They have not yet been tagged.
Wireless Microphone Report and Order and Further Notice of Proposed Rulemaking
(not filed) Addendum: Ryan's Further Thoughts on the TVBD In Service Monitoring Requirement
Mouse over or read alt text for image credits. All images from Ryan S. Overdorf are used with under a Creative Commons attribution, non-commercial license. Images with borders are hypertext links. Microsoft clip art images are used non-commercially consistent with Section 26 of the Microsoft Service Agreement and the "Clip Art and Sample Art" section of the Use of Microsoft Copyrighted Content.
