Petition to Delay by ITFS 2020

Before the

FEDERAL COMMUNICATIONS COMMISSION

Washington, DC 20554

In the Matter of )

)

ITFS 2020 )

Emergency Petition for Postponement )

Of the July 3 - July 10, 2000 Filing )

Window for Two-Way Multipoint )

Distribution Service and Instructional )

Television Fixed Service Applications )

To the Chief, Mass Media Bureau:

EMERGENCY PETITION

ITFS 2020,[1] by its attorneys, respectfully submits this Emergency Petition requesting that the Federal Communications Commission’s (“FCC” or “Commission”) Mass Media Bureau (“Bureau”) postpone the July 3 through July 10, 2000 filing window for Multipoint Distribution Service (“MDS”) and Instructional Television Fixed Service (“ITFS”) applications for two-way operations.[2] As set forth more fully below, the nine-month postponement we request is necessary to allow ITFS licensees to file applications that will permit two-way operations. Absent the requested postponement, ITFS licensees either will submit applications that turn out to be incomplete or inaccurate, and therefore unacceptable for filing, or simply will be unable to complete their applications and thus be forced to wait until subsequent filing windows to apply for two-way authorization. To the extent that some licensees are able to meet the initial window, all other nearby co-channel and adjacent channel licensees stand to be severely handicapped. As a result, the introduction of two-way services on a widespread basis will be substantially delayed, and many ITFS licensees will not be able to gain the full benefits of the advanced services and technologies necessary to further their educational missions. These licensees – and the public – will suffer irreparable harm if this opportunity is lost.

I. BACKGROUND

In a Report and Order issued on September 25, 1998, the Commission revised its rules to enable MDS and ITFS licensees to engage in fixed, two-way transmissions.[3] This action was taken in response to a petition for rulemaking filed by a significant number of MDS and ITFS licensees seeking to enhance the competitiveness of the wireless cable industry and to extend the benefits of advanced, two-way communications capabilities to the educational community. As the Commission recognized in adopting these revised rules, this increased flexibility will dramatically expand the universe of services and applications that ITFS licensees may offer to include advanced video-conferencing, distance learning, and expanded continuing education opportunities.[4] In addition, this increased flexibility will significantly increase the value of ITFS spectrum to ITFS licensees for their own use and as an asset to be leased to commercial carriers.[5] One particularly useful application could be the introduction of additional wireless local competition over the ITFS and MDS spectrum. Regardless of whether they intend to aggregate spectrum with other ITFS licensees, partner with commercial providers, or use their spectrum solely to meet their internal needs, all ITFS licensees can benefit from the ability to provide two-way services.

Applicants submitting two-way applications will be required to certify that they have met all requirements regarding interference protection to existing and prior proposed facilities, and that they have served all potentially affected parties with copies of their applications and with detailed engineering analyses.[6] Applications that are found by the Commission staff to be incomplete or that lack the required certifications will be dismissed with prejudice and the applicants will lose their priority over subsequently filed applications.[7] Where an application is found by the staff to be grantable, it is very important that all engineering calculations in fact be accurate: If at any time after the grant of an application, unauthorized interference results to a protected facility, the grantee-licensee will be required to cease operations immediately. At that point, the burden will be on that two-way licensee to prove that it is not the cause of such interference.[8]

On March 23, 2000, the Bureau announced that the first filing window for MDS and ITFS two-way applications would open on July 3 and close on July 10, 2000. Both the Commission and the MDS/ITFS industry have an interest in ensuring that the two-way licensing process begins as soon as possible. Indeed, the ITFS community has urged the Commission since the start of the two-way proceeding to expedite the availability of two-way operations for educational purposes; many licensees accordingly initially supported and even advocated the July filing deadline. However, as explained in greater detail below and in the attached declarations,[9] it has become apparent over the past month or so that licensees face certain short-term problems relating to the two-way application process that make it extremely difficult, if not impossible, for at least the great majority of ITFS licensees to prepare acceptable, grantable applications in time for the first filing window. ITFS 2020 believes that many MDS licensees also are experiencing these problems and would benefit from the requested delay. ITFS 2020 therefore respectfully requests that the Bureau temporarily postpone the first filing window to permit these problems to be solved.

II. IN ORDER TO MAXIMIZE THEIR ABILITY TO PROVIDE TWO-WAY OPERATIONS, LICENSEES MUST FILE IN THE FIRST FILING WINDOW.

Although the FCC has indicated that it will open rolling filing windows for two-way authorizations on a regular basis following the first filing window, as discussed below, these future filing windows are not a substitute for the initial filing opportunity. A significant factor in determining whether a two-way application is grantable depends upon the applicant’s ability to demonstrate that proposed two-way operations will not cause interference to existing or prior proposed operations. Thus, the ability of an applicant filing for two-way authorization for a specific market in subsequent filing windows to demonstrate that its operations will not cause interference to other licensees decreases significantly each time that a two-way application is granted for that market, with corresponding reduction in the areas it can serve. This is likely to be a particular problem in larger markets, where the greatest number of stations is located and the greatest number of initial two-way applications is anticipated. Further, those whose applications are granted first in time will have little incentive to negotiate any middle ground. By contrast, all applications filed during the initial filing window will be considered filed on the same day; as the FCC recognized, this gives applicants with conflicting proposals incentives to negotiate mutually agreeable solutions.[10] Once having missed the opportunity of filing during the first filing window, the longer ITFS two-way applicants must wait to file until after that first window has closed, the less likely their chances of ever being able to provide two-way operations throughout their entire licensed service area.

Participation in the initial filing window is especially vital for licensees that must rely on "limited exception” status.[11] This applies to all stations that now receive harmful interference within their 35-mile-radius protected service areas (“PSAs”), as is the case with many or most stations in those markets that have numerous licensed stations, particularly the largest markets. The “limited exception” permits Station A to propose two-way service that would cause interference to areas within Station B’s PSA to the extent that those areas already suffer interference.[12]

Reliance on this exception will be of critical importance to many stations. The value of this exception will decline dramatically to the extent that stations are unable to file in the first window, for the following reason: The two-way applications of Station A and B, which now interfere with each other, can be expected to involve mutual interference. If both are filed in the initial filing window, those stations will have parity of status and they will be in a position to work out their differences on a mutually beneficial basis. If they do not file in the first filing window, the race will be to the swift; thus, if Station A files even a day later than Station B, Station A will be required to provide full protection to Station B, and Station A’s service area accordingly will be severely limited. Thus, if a licensee relying on the limited exception cannot successfully participate in the initial two-way filing window -- and the Commission grants the two-way application of co-channel or adjacent channel stations -- then that licensee effectively may be confined to its present analog one-way service contours for any subsequent two-way applications. That means that the licensee and the public it serves will be denied the full benefits of innovative new digital technologies and the most efficient network designs. The FCC's procedures for this initial two-way filing window must permit all limited exception licensees who wish to do so to fully participate.

In light of these basic engineering realities, public policy reasons weigh in favor of scheduling the initial filing window so as to ensure the greatest possible participation in the first filing window. The ITFS community has worked hard to secure the option to provide two-way services because of the advantages that such flexibility will afford. These efforts will have been wasted if software and other avoidable technical limitations prevent the vast majority of ITFS licensees from gaining access to the advanced technologies necessary to further their educational mission.

III. COMMERCIALLY AVAILABLE SOFTWARE IS NOT YET RELIABLE.

As noted above, an application for two-way authorization requires that an applicant certify that it has conducted extensive engineering analyses demonstrating that its proposed two-way use will not cause interference to any existing or prior proposed operations in the applicant’s market area.[13] In the vast majority of markets, these required engineering showings are very complex and time consuming and cannot be conducted without the use of highly complex technical filing software. To date, however, there is no perfected software commercially available to ITFS and MDS licensees that is completely capable of handling the interference analyses required in the two-way application process.

As of the date of this petition, there are two providers of filing software that may be used by ITFS licensees.[14] The first software package, offered by CelPlan, was officially released on April 15, 2000;[15] the second, offered by EDX Engineering, was officially released only on May 15, 2000.[16] Significant flaws remain in each that will make filing in time for the current initial filing window virtually impossible.[17] First, neither software program is yet capable of incorporating data from any other application, whether filed using the same or the other software package. As a result, the evaluation of concurrently filed applications that is an essential part of the two-way application process will be impossible.[18] Second, neither the CelPlan nor EDX software is yet capable of accepting data from a diskette or CD-ROM, which prevents licensees from evaluating potential interference from a proposed two-way system to an incumbent licensee’s system, or between proposed two-way systems.[19] Finally, neither the CelPlan nor EDX software is yet capable of addressing the two-way interference rules’ “limited exception” status discussed above which is used to define the protected service area when station partitioned service areas overlap.[20] Significant training also is necessary in order to use the software, which dramatically increases the burden associated with filing a two-way application. For example, CelPlan recommends up to 30 days of intensive training before it may be used proficiently, and the EDX program also requires significant training to operate.[21] In total, ITFS 2020 estimates that, even when the software packages are perfected, the preparation of an accurate, complete two-way application could take between up to 1000 hours of engineering effort to complete, depending on the number of incumbents encountered.[22] Further, each time that an updated version of the software is made available, licensees who have begun to prepare applications must rerun the information in the revised program.[23]

Both software providers continue to provide updated filing software[24] and have assured ITFS 2020 that they are working to fix these problems as quickly as possible. As a result, ITFS 2020 is confident that the requested delay will result in perfected software that will allow the application process to move forward. However, as detailed above, absent the postponement requested, the current state of this software makes timely filing impossible, except for MDS licensees that intend to propose two-way systems of very limited capacity and sophistication.

IV. POSTPONEMENT OF THE FIRST FILING WINDOW WOULD PROVIDE ADDITIONAL TIME FOR THE FCC STAFF TO CONTINUE MAKING NECESSARY IMPROVEMENTS TO THE ITFS/MDS DATABASE

As discussed above, among other technical requirements, the Commission requires that an applicant for a new or modified two-way system protect all incumbent MDS and ITFS licensees from harmful interference from the proposed two-way operations.[25] As a result, access to current information regarding the technical operations of incumbent and prior proposed operations is fundamental to the two-way application process. To date, however, ITFS licensees’ preliminary efforts to prepare applications using available FCC data demonstrate that obtaining necessary technical information is too difficult within the short time left before the first filing window opens. The application process also has been complicated by the fact that although the FCC staff has indicated that it will release an up-to-date and electronically searchable database that contains all necessary licensing information in advance of the first filing window, to date no such database has been made available.[26] While MMDS/ITFS data files have been available on the Mass Media Bureau website, no file descriptions or database table definitions have yet been provided. As a result, these data files have been unusable. Very recently, the FCC has provided electronic access to individual MMDS/ITFS license files. As yet, no engineering or technical data can be obtained from such files.[27]

Without an accurate, up-to-date, electronically searchable database, ITFS and MDS licensees must instead obtain all information on incumbents’ stations from the files of the FCC’s Public Reference Room in Washington, DC. However, the need to review paper licensing records for each incumbent licensee that might be subject to interference from proposed operations makes completing the engineering analyses necessary to prepare an application for two-way operations considerably time consuming. In addition, significant restrictions on the availability of these files have severely limited ITFS licensees’ ability to determine the presence of incumbents within a reasonable time and thus have dramatically increased the burden associated with applying for two-way authorization. For example, a member of the public currently is permitted to review only three files per day, and the files are accessible only four days per week.

ITFS 2020 recognizes that improvement in public access to the Commission’s ITFS/MDS licensing information is no easy task, especially in light of the Commission’s recent need to devote staff resources to its own Y2K compliance efforts, and ITFS 2020 appreciates the ongoing efforts of Commission staff to ensure that such information is as accurate and up-to-date as possible. By temporarily postponing the initial two-way filing window, the Commission can help to ensure that the current limitations on the availability of accurate technical information do not prevent ITFS licensees from filing accurate, grantable two-way applications. First, a postponement would give the Commission staff the time necessary to make the promised electronic database available sufficiently in advance of the filing deadline to be usable by two-way applicants. Second, once an electronic database is made available, a delay would give applicants whom to date have relied on paper files in the reference room the time needed to cross reference the information in the files. Such cross checking is necessary not only with respect to information concerning other licensees’ operations, but also with respect to data describing the applicant’s own stations.[28] Third, if no electronic database can be made available well in advance of the revised filing window, a postponement would ensure that ITFS applicants have sufficient time, in light of the limitations on access to information regarding incumbents’ operation available in the reference room, to obtain the technical information necessary to complete their applications. Finally, waiting until a fully up-to-date database is available before opening the first filing window will help to eliminate any unfairness that might result to first round applicants because of information that is added to the database only after their applications have been filed. For example, ongoing changes to the database after the filing deadline could easily result in a situation where an application is petitioned and dismissed based on information that becomes available in the database only after the application has been filed. Worse still, such changes could result in unpredictable interference after the license has been granted that forces the licensee to cease all operations on that frequency.

V. THE COMMISSION SHOULD MAKE USE OF A TEMPORARY POSTPONEMENT OF THE FILING WINDOW TO CLARIFY OUTSTANDING PROCEDURAL ISSUES RELATING TO THE TWO-WAY APPLICATION PROCESS.

To date, engineers consulting with ITFS licensees have identified a number of questions relating to the two-way application process that require clarification before they can prepare acceptable applications in time for the July 3 though 10 filing window. As ITFS 2020’s engineers noted in a May 24, 2000, meeting with Bureau staff, these questions range from procedural issues relating to the mechanics of the application process, to more technical concerns relating to the nature of the engineering analyses that must be conducted for each incumbent operator.[29] ITFS 2020 appreciates that staff have addressed a number of these issues, or have assured it that remaining issues will be clarified in time for the first filing window. However, in light of the current filing deadline and the complex nature of the engineering issues involved, ITFS 2020 respectfully submits that it already may be too late for clarification of these issues to be of any practical use to most potential ITFS two-way applicants. Moreover, the vast majority of ITFS licensees may not have the resources or personnel that affords them with similar access to Commission staff necessary to resolve these ambiguities, and must instead rely on the FCC’s public notices and other publicly-released information. They also may lack the resources necessary to hire someone to complete their two-way applications for them. Given the time constraints imposed by the July 3 through 10 filing window, the laudable efforts by staff to informally assist individual licensees simply cannot constitute sufficient clarification or notice of these issues for the entire ITFS community.

Postponement of the July 3 through 10 filing window thus would provide an opportunity for clarification of all outstanding issues relating to the two-way application process. Among other things, a temporary postponement will allow the Bureau to issue clarifying public notices sufficiently in advance of the filing deadline so that ITFS licensees will be able to successfully file accurate and grantable applications. Postponement also would allow the Bureau to issue written responses to “frequently asked questions” or hold a public forum to address these issues, as is routinely done prior to the FCC’s wireless and broadcast auctions.[30] Such efforts would help to ensure that all MDS and ITFS licensees, and not simply those with the most extensive engineering resources, would have a realistic chance of being able to participate in the initial filing window for two-way operations.

VI. POSTPONEMENT OF THE FILING WINDOW FOR NINE MONTHS IS IN THE PUBLIC INTEREST.

For the reasons outlined above, ITFS 2020 believes that the Bureau should promptly issue a public notice postponing the first filing window for nine months from the originally scheduled July 3, 2000 start date. ITFS 2020 estimates that a postponement of this length is necessary as follows: ITFS 2020 believes that it will require at least 30 days for the filing software and the Commission’s database to be perfected.[31] It will take approximately two months for applicants’ engineers to be trained on commercial software and become confident that this software meets their application needs, and to verify that the information available in the FCC’s electronic database is the same as that contained in the files in the public reference room. Assuming the database is sufficiently up-to-date, it then will take approximately six months to prepare and file applications. Based on its experience to date, ITFS 2020 estimates that by working diligently from the time usable software is made available, this limited postponement will provide a realistic chance for most licensees to complete two-way applications in time for the first filing deadline.

Given the circumstances, a nine-month postponement is reasonable. A shorter delay would not take into account the time required to prepare a grantable two-way application (even with usable software) and thus would be useless given the limited resources of many ITFS licensees. In contrast, a longer postponement could unnecessarily delay the long-awaited deployment of two-way services. Moreover, this temporary delay is clearly in the public interest. It will ensure that all ITFS licensees who are interested in providing two-way services are given a true opportunity to file acceptable applications with the Commission. It also will increase the likelihood that applications that are filed will be found acceptable by the Commission and will contain the accurate engineering analysis envisioned by the Commission when it adopted its two-way rules. Indeed, no applicant is likely to be prejudiced by such a postponement, as no one, regardless of resources, can confidently file an application until the problems ITFS 2020 has identified are remedied.
VII. CONCLUSION

For all of the foregoing reasons, ITFS 2020 respectfully requests that the Bureau grant this emergency petition for nine-month postponement of the initial filing window for ITFS two-way applications, and announce the postponement as soon as possible so that ITFS licensees may plan accordingly. This temporary postponement will ensure that the ITFS community is able to realize the full benefits that the Commission envisioned in adopting rules to permit two-way operations on ITFS spectrum.

Respectfully Submitted,

______________________________________

Lynn R. Charytan

Daniel B. Phythyon

Josh L. Roland

WILMER, CUTLER & PICKERING

2445 M Street, N.W.

Washington, D.C. 20037-1420

(202) 663-6000

Counsel for ITFS 2020, L.L.C.

June 6, 2000

Insert Hidle Declaration, Duncan Declaration, May 24 handout.

I, John Meehan, do hereby certify that on the ____ day of June, 2000, I caused true and correct copies of the foregoing Emergency Petition of ITFS 2020 to be served by hand* or by first-class mail, postage prepaid, upon the parties on the attached service list.

3. Carl T. Jones Corporation has been retained by ITFS 2020, L.L.C. to assist in the preparation of applications for two‑way ITFS service. Other entities also have sought our services in connection with the preparation of two‑way applications for the ITFS and MDS services.

perform extensive calculations that realistically can not be done manually. Two new software packages have been designed to accomplish that task. CelPlan Wireless Global Technologies has developed a multi‑module

persons to receive an initial two‑day training session prior to the April 15th

release date. We recently had six engineers attend an additional three‑day formal training session at CelPlan. EDX Engineering, Inc. has also developed an additional module to be used in conjunction with an existing RF design and evaluation tool, SignalPro 3.0. The official release date on this module was May 15, 2000. We arranged for two persons to attend a two‑day training seminar a few days after the release date. We are still evaluating the EDX MMDS module as a solution to the challenge of two‑way ITFS/MMDS system design and application preparation. To date the accuracy of the two software design application programs has not been verified.

9. In our experience, the interference analysis described in Appendix D of the Report and Order on Reconsideration is by far the most complex process ever adopted by the FCC. Both CelPlan and EDX continue to improve their respective tools; in our opinion, however, more time is necessary for completion of development and final validation of both software packages.

unusable. Very recently, the Commission has provided electronic access to individual MMDS/ITFS license and application files. As yet, no

available; furthermore, accurate applications cannot be prepared until such a database is available. Providing additional time will not only protect

11. Procedural and Technical Issues Requiring Clarification. Our experience in preparing ITFS and MMDS applications also suggests that the FCC's further clarification of a number of issues is necessary before we will be able to prepare fully complete and acceptable two‑way systems applications. Requested further clarifications include: (1) procedures and methodology for filing applications electronically; (2) number of individual Forms 331 that an applicant must file where multiple types of facilities are located at the same site or where multiple applicants make use of a combined Form 331; (3) necessity for conversion of all

served with interference analyses, and what form such service should take; and (6) serving the FCC's copy contractor (ITS) with interference analyses for each affected incumbent, despite the fact that each such incumbent will already have been served with this information. These issues should be further clarified well in advance of the filing deadline or else it will likely be impossible to prepare complete and acceptable applications for two‑way ITFS and MMDS systems.

I declare under penalty of perjury that the foregoing is true and correct to the best

2. I am Executive Director of the National Conference on Citizenship (NCOC); my office, which is NCOC’s Capital Area office, is located in Falls Church, Virginia. NCOC holds seven ITFS licenses, for channels in Albany, NY, Rochester, NY, Hartford, CT, Buffalo, NY, Knoxville, TN, Binghamton, NY, and Burlington, VT; we also have an application pending for a license in Bellows Falls, VT. NCOC desires to file applications with the FCC for two-way authorization for each of its licenses.

3. In exploring how to file two-way applications on behalf of NCOC, I have conferred with consulting engineers who have been working on preparing two-way applications using the software package created by CelPlan Wireless Global Technologies. The consulting engineers have informed me that, in order to have complete confidence in the accuracy and reliability of the results produced by the CelPlan software, they must compare the CelPlan results with results produced by another software package designed for the same purpose. However, I have learned from the engineers that presently there is no adequate alternative software package available; the one other commercially available software package for preparation of two-way applications is still a work in progress, and is simply too undeveloped to provide an adequate basis for comparing the output of CelPlan’s software, which the engineers require in order to have confidence in CelPlan’s results. The unavailability of an adequate second software package therefore presents a serious obstacle to NCOC’s ability to prepare a complete, reliable and accurate application in time for the FCC’s July 3-10, 2000 filing deadline.

4. I also understand from the engineering consultants that, in light of the analyses required to complete two-way applications, it is not practicable for them to manually prepare such applications.

5. I am aware of another obstacle presently impeding the timely preparation of a complete and accurate two-way application: the unavailability of complete and reliable information about other licensees in electronic form. While I am appreciative that the FCC recently placed licensee information on its website, in my experience the database as currently available is incomplete. For example, I discovered after performing a search that the database does not include all of the licensees in every market. This type of information is critical to the filing of complete and accurate two-way applications. Collection of this information manually, by way of the FCC Reference Room, is very time-consuming and burdensome.

6. In light of these facts, I do not feel at this time that NCOC will be able to prepare complete, reliable and accurate two-way applications by July 3-10, 2000. If the FCC's filing window were postponed, I believe that it would be possible for a second software package to be fully developed and implemented as an adequate comparison to ensure the reliability and accuracy of results produced by the CelPlan software package. This information could then be used by consultants in preparing reliable and accurate two-way applications within the revised filing window deadline. In addition, there also is the possibility that, in the extra time provided by a postponement of the filing window, the FCC might make available a complete and accurate electronic database that is fully searchable, so that applicants could rely on information taken from that database in preparing two-way applications.

Specific details are required setting forth the method for electronically filing applications. Subsequent Commission Public Notices have been promised to provide this material. The question is: WHEN WILL THESE PUBLIC NOTICES BE ISSUED?

Instructions for Form 331 state that “A separate application must be submitted for each response station hub, signal booster station or I Channel station at a separate site.” Does this mean that an applicant is permitted to apply for multiple facilities at the same site using a single Form 331? Is the operative factor “one 331 form per site”? Conversely, if an applicant wishes to file for six sites, must it file six applications, or can it add pages to a single application?

The instructions state that “A group of applicants may file on a combined FCC Form 331 for any new or modified MDS or ITFS booster station, response station hub, or 125 kHz (I channels) point-to-multipoint, so long as the geographic coordinates are the same.” Does this mean that a group of licensees each holding a channel group could file on a single Form 331 for a common response station hub, and a booster station which employs all channels in all groups? May we be permitted to save paper by filing one Form 331 per site to include all proposed applicants and all proposed facilities by all applicants at that site?
GEOGRAPHIC COORDINATES REFERENCE:

A reminder that all geographic coordinates must be referenced to the North American Datum 1983 (NAD83) reference, not the NAD27 reference which is used for current facilities at the FCC. (The FAA uses NAD83 for tower and structure locations) Heretofore the FCC has maintained use of the NAD27 reference. Most currently available USGS topographic maps were produced based on NAD27. Recent reprints include NAD83 corner tics. The salient question is: Must we convert every set of geographic coordinates for every existing or proposed facility to be studied from NAD27 to NAD83 prior to performance of the required interference analyses? Or, in the alternative, may we use NAD27 coordinates to conduct the required interference analyses to other facilities and then convert only the coordinates of the proposed station to NAD83 for filing?

The instructions for Question 10 on FCC Form 331 address the “incumbent” MDS or commercial ITFS licenses regarding the coordinates of the fixed 35 mile circular protected service area. On September 15, 1995 the center coordinates became fixed at the then authorized or previously proposed coordinates. How does this affect the possible application of the “limited exception” definition of a protected service area? The partitioned service area is treated differently as to how interference is determined. It is, in most cases, imperative that we be allowed to invoke the “limited exception”definition of the “incumbent” station’s protected service area, however, there appears to be no provision on the Form 331 to do so.

Additionally, the “limited exception” is described in Paragraphs 24 and 25 of the Second Order on Reconsideration (FCC 95-231) which was adopted on June 15, 1995 and released on June 21, 1995. This “limited exception” was adopted in conjunction with the expansion of the Protected Service Areas of MDS stations from the 710 square mile area within 15 mile radius circle to a 3848 square mile area within a 35 mile radius circle. The adoption of the “limited exception” to the definition of the PSA recognizes existing interference between incumbent co-channel stations which upon expansion of the PSAs does not disappear. The exception enables an incumbent who seeks to modify his facilities to exclude from the PSA of