“A Review of the FCC’s Spectrum Management Responsibilities in Addition
to H.R. 3439, the ‘Radio Broadcasting Preservation Act’”
Committee on Commerce, Subcommittee on Telecommunications,
Trade and Consumer Protection
United States House of Representatives
February 17, 2000
The FCC’s Spectrum Management Responsibilities
I would like to begin with an overview of the Commission’s role in managing the radio spectrum. Under Section 303 of the Communications Act, which defines the general powers of the agency, the FCC is tasked with assigning bands of radio frequencies to the various classes of stations, assigning frequencies and power for individual stations, and specifying the locations where classes of stations or individual stations may operate. In addition, Section 7 of the Communications Act states: “(I)t shall be the policy of the United States to encourage the provision of new technologies and services to the public.” Effective management of the radio spectrum is therefore a core responsibility of the FCC.
Spectrum is a valuable and finite public resource that must be allocated and assigned in a manner that will provide the greatest possible benefit to the American public. Consistent with the FCC’s statutory obligations, we view our mission in the Office of Engineering and Technology (OET) as ensuring that the radio spectrum is used efficiently and effectively. One of our principle jobs is to help to define policies that maximize the efficient use of the spectrum and promote the introduction of new services and technologies. OET, for example, developed the allocation plans for cellular and PCS wireless communications services and for digital television service.
Over time, technological advances, growth in user demand, and the finite nature of spectrum have made our spectrum management responsibilities increasingly complex. To address the continuing growth of demand for radio services, we have focused our approach to spectrum management on allowing spectrum markets to make more efficient use of frequency bands through new technologies and on increasing the amount of spectrum available for use. In addition, we have sought to encourage the development and deployment of new, more spectrum-efficient technologies that will increase the amount of information that can be transmitted in a given amount of bandwidth and to allow greater use of the spectrum occupied by existing services wherever possible.
Under this approach, new services have been implemented either through sharing with existing operations or through reallocation of spectrum from existing services to new services and technologies. In this regard, we have, for example, developed plans for sharing between satellite and terrestrial fixed services and for recovery of spectrum from existing uses to make way for new technologies. The spectrum used for PCS service at 2GHz was recovered from fixed microwave services that were relocated to higher bands. In addition, the efficiency of the digital television transmission standard has made it possible to plan for the reallocation of the 108 MHz of spectrum now used for television channels 52-69 to new public safety, commercial wireless, and broadcast services.
Low Power FM Radio
I next will discuss the Commission’s decision to allow the operation of low power FM stations. In its January 20, 2000, Report and Order in MM Docket No. 99-25, the Commission authorized the licensing of two new classes of low power radio stations -- one operating at a maximum power of 100 watts and the other at a maximum power of 10 watts. The new LPFM stations will be licensed to operate on a noncommercial educational basis only, and to parties that do not hold an attributable interest in any other broadcast station or media. The rules also provide for a significant preference to locally based applicants.
The Commission has taken a conservative approach in protecting existing FM service. For example, the Commission did not adopt its original proposals to permit 1000 watt, commercial LPFM stations and to allow LPFM operations on 2nd adjacent channels. In addition to specifying low power operation, the rules provide a number of other safeguards to protect existing FM stations, such as limitations on antenna height and separation requirements for low power stations with respect to full power stations operating on the same channel, on 1st and 2nd adjacent channels, and on intermediate frequency channels. We also added a 20 km buffer to the required separation distances between LPFM and full service stations that are operating on co- and 1st adjacent channels. This buffer will provide an additional margin of protection for full power stations that modify or upgrade their facilities.
We did not, however, impose requirements for separation of LPFM stations from stations on 3rd adjacent channels. From the considerable technical record in our proceeding, we found that LPFM operation on 3rd adjacent channels will not result in significant new interference to the service of existing FM stations. Our discussions with, and comments from, proponents of new digital radio technologies also indicate that LPFM operations on 3rd adjacent channels will not impact potential future digital services in the FM band. (See attached illustration of 1st, 2nd and 3rd adjacent channels on the FM radio dial.)
Our decision in this matter followed a nearly one-year long public comment period extended four times between January and November 1999. We granted these four extensions at the request of the broadcasting industry, at times over the strong opposition of other parties in the proceeding. We did so to give broadcasters and all other parties a more than ample opportunity to comment on the proposed LPFM service. During this lengthy comment period the Commission received significant expressions of interest and public support for LPFM service. The Commission received comments and letters from thousands of individuals and groups seeking licenses for new radio stations. These comments -- from churches or other religious organizations, schools, colleges, students, community organizations, musicians and other citizens -- reflected a broad interest in, and need for, service from highly local radio stations that are strongly grounded in their communities. The plan for LPFM service adopted by the Commission will address these needs by enhancing listeners’ access to locally focused, community-oriented radio broadcasting.
In providing for the operation of LPFM radio stations, we have followed the principles of our general approach to spectrum management: the new LPFM stations will share the FM radio spectrum with existing stations, thereby making more efficient use of the FM band. In establishing this service, the Commission was also following two longstanding foundation principles under Section 307(b) of the Communications Act in providing spectrum for broadcast use. The first is to promote a diversity of media voices. The second is to adopt policies that facilitate and encourage the operation of broadcast services that meet local needs and specialized interests wherever possible. Consistent with these principles, the Commission's first goal in establishing a new LPFM service was to create a class of radio stations that would serve very localized communities or underrepresented groups within communities. This new service will enhance service to the public by providing service opportunities for parties who had previously been denied access to broadcast spectrum. A second, specific, goal was that the LPFM service include the voices of community-based schools, churches, and civic organizations.
The Commission in planning for the LPFM service also emphasized that it would not compromise the integrity of the FM radio spectrum. The Commission was particularly cognizant of the concerns of FM broadcasters with regard to both existing service and possible options for FM stations to provide digital service. Addressing these concerns, the Commission stated that it was determined “to preserve the integrity and technical excellence of existing FM radio service, and not to impede its transition to a digital future.” In this regard, the principal technical issues in this proceeding have been the potential for new low power stations to cause interference to existing FM radio service and to impact future digital radio technologies, such as In-Band On-Channel, or “IBOC,” systems. Based on our own technical studies and analyses of studies by a number of others, we are convinced that LPFM service, as provided under the new rules, will not adversely impact reception of full service FM stations, nor will it affect the transition of these stations to digital service using IBOC technology that transmits digital signals on adjacent channels.
Third Adjacent Channel Protection Is Not Necessary
Of course, I am aware of the differences of opinion that exist, particularly on the part of full service FM stations and their representatives, over whether LPFM stations will cause interference to existing FM service. The principal issue here is over whether we should have imposed 3rd adjacent channel restrictions on LPFM stations. The main determinative factor is the ability of FM receivers to operate satisfactorily when signals from LPFM stations are present on 3rd adjacent channels. I believe that the record provides strong support that 3rd adjacent channel restrictions are not needed for LPFM and that any areas experiencing interference would be very small and would be outweighed by the benefits of the new service.
Initially, I would point out that during the period from 1964 to 1987, pre-1964, “grandfathered,” short-spaced full power FM stations were permitted to modify their facilities without regard to either 2nd or 3rd adjacent channel spacings. No interference complaints were received as a result of such modifications, and this policy was re-instituted in 1997, again without subsequent interference complaints. Similarly, in 1991, the Commission decided to accept small amounts of potential 2nd and 3rd adjacent channel interference in the noncommercial FM service where such interference is counter-balanced by substantial service gains.
In addition to these historical precedents, the technical data submitted in the proceeding also supports the conclusion that 3rd adjacent channel restrictions are not needed to protect full service FM stations from LPFM operations. As you are aware, three technical studies of FM receivers were filed in response to the Commission’s Notice of Proposed Rule Making. These studies were submitted by the Consumer Electronics Association (CEA), the National Association of Broadcasters (NAB), and the National Lawyers Guild (NLG).1 In addition, our Office conducted its own study of a sample of 21 FM receivers. Taken together, the studies examined 75 consumer FM radios of various types and performance capabilities, including automobile radios, component tuners or receivers, portable radios such as “boom boxes,” personal radios such as “Walkman” type units, and clock radios. Finally, the NAB and CEA filed supplementary technical information in their reply comments, and the Media Access Project submitted in its reply comments a Technical Analysis of the Low Power FM Service prepared by Professor Theodore Rappaport, James S. Tucker Professor of Electrical Engineering, Virginia Tech, and Chairman, Wireless Valley Communications, Inc., Blacksburg, Va.
These studies provide a substantial body of information on FM receiver performance in the presence of interfering signals. Unfortunately, the studies used different methodologies that make direct comparisons between them difficult. However, as the NAB stated in its reply comments, the significant differences among the studies were not in the measurements or in the performance of the radio receivers tested, but rather, in the definition of impaired reception. We generally concur with that assessment and believe that the most significant differences in the conclusions of these studies are the result of variations in the definitions of desired service and when the desired service is impaired.
-NAB/CEA Criteria Are Inappropriate for Today’s FM Service
Both CEA and NAB, for example, generally find the performance of today’s FM radios unacceptable because they do not meet their presupposed desired levels of performance. For example, 17 of the 28 radios tested by the NAB failed to meet its standard of 50 dB audio signal-to-noise ratio (S/N) performance with no interference present and with the “strongest” desired signal level tested.2 Similarly, CEA reports that none of its sample receivers “came near meeting” its 45 dB S/N performance target at the current FCC protection standards for full power co-channel stations. While such performance levels may indicate more interference from prospective LPFM stations, we fail to see how such levels can be appropriate measures when most radios do not perform to these levels, even in the absence of any interference, as was the case in NAB’s tests.
Moreover, we have seen no indication from consumers that they find that the vast majority of FM receivers do not provide satisfactory service. Therefore, as stated in our Report and Order, we do not find the S/N levels suggested by CEA or NAB to be appropriate interference criteria for today’s FM radio service. We also note that a previous study by the NAB indicated that the current FCC co-channel protection requirement for FM stereo yields an audio S/N of about 30 dB, not the 50 dB suggested by NAB in its technical study. 3
-Receivers Are Better at Rejecting 3rd Adjacent Channel Interference
Notwithstanding the differences among the technical studies regarding performance standards, there are important consistencies in the study results that we find support a conclusion that 3rd-adjacent channel restrictions are not needed for LPFM stations. All four studies show that the ability of FM radios to reject interference from signals on a 3rd adjacent channel is generally much better than from interference from signals on a 2nd adjacent channel. This is to be expected since 3rd adjacent channel is further removed from the desired channel to which you are tuning. (See again the attached illustration.)
The OET and NLG studies generally conclude that FM receivers provide for adequate rejection of interference on 2nd and 3rd adjacent channels. The OET study, for example, finds that nearly all of our receivers appear to meet the 2nd adjacent channel protection criteria and exceed the 3rd adjacent protection criteria by about 8-10 dB, a wide margin. While CEA and NAB argue that their studies show that the adjacent channel protections should be retained, a review of CEA’s results shows that its median receiver provides about -40 dB of rejection of 3rd adjacent channel interference, and that this margin of performance is about 3 to 7 dB better than 2nd adjacent performance for its sample. Similarly, the NAB tests also show 3rd adjacent channel performance to be substantially better than 2nd adjacent -- on the order of 8 to 10 dB. This means that radios can generally reject signals on a 3rd adjacent channel that are about six to ten times stronger than signals on 2nd adjacent channels.
The studies also found that automobile radios and home stereo/component receivers tend to be more effective at rejecting adjacent channel interference than clock, personal and portable radios. Our examination of the studies indicates that automobile radios and home stereo/component receivers generally are able to provide -40 dB or more rejection of 3rd adjacent channel signals and therefore generally will provide acceptable service in the absence of 3rd adjacent channel protection. NAB’s test results, for example, show that FM radios in automobiles, where most FM listening is done, meet the current -40 dB criteria.
We also recognize that poorer quality receivers, such as personal and clock radios, may experience some additional interference as a result of eliminating the 3rd adjacent channel protection for LPFM stations. We note, however, that these classes of radio may also experience some degree of interference from co- and 1st adjacent channel full power FM stations operating within the existing protection requirements. We also believe that consumers generally understand that there are performance differences among the classes of radios and that they accept the fact that lower cost radios may provide more limited service capabilities. We therefore believe that our decisions with regard to LPFM service should not be constrained solely by the performance limitations of lower cost radios any more than we should use those radios to redefine existing FM radio service. For example, if we were to define acceptable FM radio service using NAB’s performance measure and NAB’s median test results for personal radios – the radius of a 6 kilowatt Class A radio station’s protected service area would go from 27.5 km to less than 10 km. This is because such radios do not provide acceptable service as defined by NAB beyond about 10 km, even in the absence of any interference. I do not believe that this is a realistic approach, as this would ignore service provided to radios that provide more typical performance, and would unfairly reduce the station’s expected audience reach.
-Potential Interference from LPFM is Small
We also found that the area in which any additional interference would be likely to occur from an LPFM station operating on a third adjacent channel at maximum facilities of 100 watts and antenna height of 30 meters above average terrain would be very small and occur only in the immediate vicinity of the LPFM station. For example, even using NAB’s median receiver performance test results for its three “worst” FM radio categories, i.e., clock, personal and portable, we find that the area where such receivers could potentially experience degradation from interference is small, generally 1 km or less. This interference analysis is shown in the following table:
|Receiver Category||Desired Signal Level|
(Close to Station)
|Clock||0.3 km (0.2 mi.)||0.7 km (0.4 mi.)||2.1 km (1.3 mi.)|
|Portable||1.0 km (0.6 mi.)||0.9 km (0.6 mi.)||1.0 km (0.6 mi.)|
|Personal||0.4 km (0.3 mi.)||0.5 km (0.3 mi.)||0.5 km (0.3 mi.)|
The above Table shows the approximate radius around an LPFM station where interference could potentially occur to a 3rd adjacent channel full service station with different types of radios, based on the NAB test data. As indicated in the Table, the area of potential interference depends on the type of radio used and on whether the LPFM station is located relatively close to the “desired” full power station, i.e., at the -45 dBm contour, or whether the LPFM station is at the edge of the full power station’s service area, i.e., at the –65 dBm contour. For example, if an LPFM station is located about 9 or 10 km from a 3rd adjacent channel Class A full power station (-45 dBm), a listener using a clock radio located about 0.3 km (about 1000 feet) from that LPFM station could experience some degradation in service. If the LPFM station is located at the edge of service of the full power station, the radius of potential interference would increase to about 2.1 km. Alternatively, if the listener were using a personal or “Walkman” type radio at the edge of coverage of the full power station, the potential interference area would have a radius of about 0.5 km.
It should be noted, however, that the actual audio S/N value that NAB uses to “define” where interference begins would be different for these two cases. For clock radios, interference at the edge of coverage would be said to begin to occur at a value of 41.5 dB S/N. This is a level we believe that most listeners would find more than acceptable for clock radio use. In the case of the personal radio, the value would be 20.3 dB, which may indicate, as discussed above, that these radios are not providing satisfactory service out to the protected contour of a full service station.
Further, we believe that this analysis provides a conservative estimate of the actual interference potential of LPFM, given NAB’s performance criteria and the fact that NAB’s sample included some of the poorer performing radios among the four studies. In addition, whether interference, in fact, occurs to FM listening depends on a number of factors, besides the performance of the FM receiver. These include, among other things, the actual reception conditions, such as the location and position of the radio, the frequency and location of both the desired and undesired stations, and the type of program material being transmitted and received. CEA noted, for example, that when the desired signal was modulated with rock music the interference was masked in its 2nd and 3rd adjacent channel subjective tests.
Based on the record before us, we therefore found that LPFM stations operating with 100 watts power or less on 3rd adjacent channels would not result in significant new interference to the service of existing FM stations. The Commission also concluded that any small amount of interference that might occur would be outweighed by the benefits to listeners from the new services to be provided by LPFM stations. With regard to 2nd adjacent channel protection requirements, we concluded that, since receiver performance appears to be only at about the same level as that provided in the rules, the risk of interference from LPFM signals on 2nd adjacent channels may be somewhat higher. We therefore applied 2nd adjacent channel separation requirements to these stations that are consistent with the -40 dB standard reflected in the current FM rules.
In concluding, I want to express my gratitude to the Subcommittee for the opportunity to appear before you today. The Commission understands and shares the industry’s concerns for protecting the integrity of the FM band. Please be assured that we have made every effort to consider all the available information in this matter. I believe the Commission’s LPFM decisions fairly address the concerns of all interests and that this new service will not compromise existing FM service. I would be pleased to answer any questions you may have.