APPENDIX B: AMATEUR SHARING STUDY

INTRODUCTION

The preliminary reallocation plan identified the 2300-2310, 2390-2400, and 2402-2417 MHz bands as part of the 200 MHz to be reallocated to the FCC for non-Federal use. These bands are allocated to the amateur and amateur-satellite services on a secondary basis. Based on the public comments, subdividing the 2400-2450 MHz band into three parts, as proposed in the Preliminary Report, would not meet the needs of the principal users of the band. However, reallocating the entire 2400-2450 MHz band would give the FCC greater flexibility in developing a comprehensive plan to address the spectrum needs of the amateurs as well as the other users of the band. Therefore, the 2400-2402 and 2417-2450 MHz band segments will be included in the final reallocation plan for mixed Federal and non-Federal use.

Though NTIA's proposed reallocation to the FCC for non-Federal use does not in itself deny these frequencies to the amateur radio services, the amateur radio community believes these actions set the stage for the amateur services having limited access in the reallocated bands. Title VI requires that the Secretary of Commerce determine the extent to which, in general, the private sector can share the frequencies to be reallocated with the incumbent amateur radio licensees.[EN1] This requirement presupposes that NTIA knows the specific types of potential commercial and public-safety applications intended by the FCC for the reallocated spectrum, or at least the range of possible uses. Until candidate radio services are selected or at least identified, it is difficult for NTIA to conduct the mandatory sharing study required by Congress in Title VI. The only practical means for the Secretary to discharge NTIA's statutory obligation is to conduct a general sharing study based on information about present and near-term future amateur uses of the segments proposed for reallocation, and a range of possible commercial and public-safety applications.

AMATEUR BAND USAGE

The 2300-2450 MHz band comprises part of the spectrum known in the amateur community as the 13 cm band. The amateur allocation at 13 cm is currently split into two parts: 2300-2310 MHz and 2390-2450 MHz. A band plan outlining the structure of amateur spectrum uses and needs for the 2300-2450 MHz band is given in Figure B-1.[EN2] As indicated in the Figure B-1, the amateur radio community intends to develop the 2300-2450 MHz band for the following uses: weak-signal experimentation, narrowband and wideband point-to-point linking, satellite activities, and amateur television transmission.

FIGURE B-1: 2300-2450 MHz Amateur Band Plan.

SHARING WITH AMATEUR OPERATIONS

The amateur radio service has successfully co-existed with Federal fixed, mobile and radiolocation services (i.e., radar) for nearly fifty years.[EN3] As indicated in many of the public comments on the Preliminary Report and the FCC NOI, this sharing arrangement has been successful for both Federal and amateur spectrum users. This success is primarily due to the fact that much of the Federal spectrum usage is located away from populated areas, minimizing potential interference as well as the amateur's ability to utilize the guard bands placed between different types of Federal services.[EN4] In addition to the Federal Government, the amateur radio service shares the 2400-2450 MHz segment with non-licensed devices and Industrial, Scientific, and Medical (ISM) devices. Recently, amateurs have indicated that there are practical problems sharing spectrum with commercial services that have a relatively high transmitter power, a high number of stations in heavily populated areas, and/or high duty cycle.[EN5] The following paragraphs will examine in general the sharing possibilities for each of the four amateur radio operations that could be potentially impacted by the spectrum reallocation.

Weak-Signal Operations

Currently most amateur weak-signal operations take place at or near 2304 MHz. The comments submitted by representatives of the amateur radio service on the Preliminary Report indicate that the spectrum from 2448-2450 MHz is also of interest to amateurs involved in weak-signal operations.[EN6] Amateurs are engaged primarily in employing weak-signal techniques for extended range communications. [Amateur weak-signal stations communicate by many propagation methods such as tropospheric ducting and scatter; low atmospheric inversion ducting; refraction and reflection off natural objects (i.e., mountains); and EME (moonbounce), to name a few.] Weak-signal stations typically employ sensitive narrow bandwidth receivers (3 kHz or less), high transmitter power, and highly directional antennas. Most of the time the highly directional antennas are pointed well above the horizon.[EN7] Based on these operational constraints the amateurs indicate that weak-signal stations could co-exist with certain commercial or public-safety terrestrial operations. The receivers used in weak-signal communications are sensitive and cannot operate in a high-noise environment; therefore, sharing with a high-power, high-density commercial application is considered impractical.[EN8] Commercial satellite applications are also likely to conflict with typical weak-signal operations. The amateurs feel that satellite uplinks would be a problem since as a satellite transponder travels over the horizon, it could be easily saturated by the high-power signal emitted from a weak-signal transmitter.[EN9] Satellite downlinks are also seen as potential problems because of the sensitivity of the weak-signal receivers

Television Operations

As shown in Figure B-1, amateur television (ATV) will occupy three channels: 2410-2427, 2427-2433, and 2433-2450 MHz. The concern expressed by the amateur community is that a loss of spectrum at the lower portion of the 2400 MHz band would force other displaced amateur operations into the ATV channels.[EN10] With ATV likely to evolve to a digitally compressed format, it will have a better chance to co-exist in a high interference environment.[EN11] In addition, the rapidly expanding use of digital compression at reasonable costs may lessen the need of 40 MHz for ATV operations. However, the amateur commenters feel that if the spectrum is reallocated for commercial applications with a high duty cycle, the band would be rendered virtually unusable for ATV.[EN12] Currently ATV operates in the presence of ISM and spread spectrum non-licensed devices. Most ATV operations are expected to occur in residential areas, or proximate to residential areas, with current uses primarily in metropolitan areas near cities and suburbs. The simplest type of commercial use to accommodate in these allocations would be licensed terrestrial point-to-point stations, or services not routinely located proximate to residential areas. Commercial or public-safety applications with low duty cycles would be more likely to avoid interference to and from ATV operations in the same band, and digital operation would be preferred over analog technologies. Wide bandwidth and spread spectrum uses are particularly suitable to sharing with ATV operations.[EN13]

Point-to-Point Operations

Point-to-point amateur operations involve paired frequencies with spacing from 40 MHz to 150 MHz. This is accomplished by using portions of the 2300-2310 MHz and the 2390-2400 MHz bands. Two bands are required because transmission and reception from one site simultaneously normally involves using different frequencies to increase isolation between the transmitter and receiver. Amateur point-to-point applications use high-performance receivers to ensure good path reliability. These receivers are protected by filters sufficient to reject their own transmitter operating on the same antenna. These filters are more than sufficient to reject near-band or out-of-band interference of any normal magnitude.[EN14] The amateur fixed point-to-point services may effectively use the same spectrum as low-power spread spectrum or medium bandwidth digital commercial devices intended for localized uses.[EN15] Several public-safety commenters to the FCC suggested that the 2390-2400 MHz band would be particularly suitable for the advanced private mobile communications technologies described in the COPE Petition, including private fixed service microwave operations at remote site locations.[EN16] Electronic Toll and Traffic Management (ETTM) systems could possibly share with amateur point-to-point operations. ETTM systems are low-power, low duty cycle devices employing directional antennas.[EN17] In general these systems will be used on highways away from residential areas where interference problems could be handled on a case-by-case basis. The amateurs also feel that high-power wide-area operations should be restricted in favor of more localized commercial and public-safety applications.[EN18]

Satellite Operations

Amateur-satellite downlink operations are planned for the 2400-2410 MHz portion of the 2300-2450 MHz band as shown in Figure B-1. However, all current and near future amateur-satellite usage can be accommodated in the 2400-2402 MHz band segment. TABLE B-1 gives a list of the amateur-satellite operations in the 2400 MHz band.[EN19] The amateur-satellite community is planning to increase its use of 2400-2402 MHz to include uplinks on the next generation of satellites. 
  
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TABLE B-1: Amateur-Satellite Usage in the 2400 MHz Band
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Amateur-Satellite              Band (MHz)
----------------------------------------------------------
AMSAT-OSCAR 13      2400.711-2400.747 & 2400.650
UOSAT-OSCAR 11                2401.5
PACSAT (AO-16)                2401.1
Dove (DO-17)                  2401.22
Phase 3D          2400.500-2400.900 & 2400.100-2400.500
==========================================================
Amateur-satellite operations employ a relatively weak signal and often use high-power terrestrial transmitters. This poses interference potential to adjacent operations and those operations pose potential interference to the terrestrial satellite receivers (most commonly through excessive sideband noise). The amateurs feel that any adjacent operations should be limited to an assigned occupied bandwidth of 50 to 100 kHz to minimize sideband noise. The amateurs contend that this bandwidth limitation for commercial and public-safety systems will also encourage the use of filtering on the adjacent systems receivers which will aid in protecting them from high-power satellite (terrestrial) transmitters.[EN20] In evaluating the feasibility of frequency sharing with the amateur-satellite service, it is important to realize two distinct types of satellites are employed in this service. One is the high-altitude, elliptical orbit type of satellite. The other, more numerous type is the low-earth-orbit (LEO) satellite, generally in circular orbits below 1000 kilometers in altitude. During approximately half the time in which an amateur LEO satellite is within range of an earth station, it is less than 10 degrees above the horizon. Thus, unlike commercial services using geostationary spacecraft, the elevation angle of amateur earth stations is unlikely to provide much, if any, relief from interference from and to terrestrial services.[EN21] Spread spectrum local area networks can effectively share with amateur-satellite operations, because satellite receivers are generally not collocated with those type of devices.[EN22] The amateur-satellite community as a whole is concerned about sharing spectrum with high-density mobile commercial services. The general consensus among amateur commenters is that it would be far less difficult to share with point-to-point microwave links since the chances of interference would be relatively slight and could be dealt with on a case-by-case basis.[EN23] Several public-safety organizations suggested that spectrum in the 2400-2450 MHz band could be used for private fixed microwave service operations in remote locations.[EN24] The amateurs also indicate that low-power, low duty cycle ETTM systems using directional antennas can also share with amateur-satellite operations.

SUMMARY

The importance of the 2300-2450 MHz band to the amateur radio service is principally in the near future. The sharing opportunities between amateurs and commercial services depend largely on the development of a sharing plan which will permit the orderly growth of the amateur users of the bands while at the same time supporting commercial and public-safety applications. The fundamental ability of the amateurs to continue operations in the reallocated bands is dependent largely on the characteristics of the commercial and public-safety applications that are to be added to the bands. TABLE B-2 provides an overview of the potential impact to current and future amateur operations and possible sharing options between the amateur service and commercial and public-safety applications. 
            
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TABLE B-2: Overview of Potential Impact to Amateur Operations and Sharing Options
====================================================================================================================
                               
 Amateur
Operation                      Potential Impact                          Sharing Options
--------------------------------------------------------------------------------------------------------------------   
                                                Weak-Signal
--------------------------------------------------------------------------------------------------------------------                          
 2304 MHz        Potentially impacted by spectrum reallocation;  Federal Government; Non-licensed device (Part 15) 
                 Protecting 0.5 MHz around 2304 MHz would        applications; Certain commercial terrestrial and 
                 eliminate impact.                               public-safety applications.

 2450 MHz        Not impacted by spectrum reallocation.
--------------------------------------------------------------------------------------------------------------------  
                                                Amateur TV
--------------------------------------------------------------------------------------------------------------------                          
Current analog   1 of 3 channels potentially impacted;           Federal Government; Industrial, scientific, and
                 Conversion of one ATV channel from              medical (ISM) applications; Part 15 applications.  
                 FM to AM would minimize impact.

Future digital   Expected minimal impact; at least 11            Federal Government; ISM applications; Part 15 ap-
                 compressed video channels, each                 plications; Commercial spread spectrum applications;
                 3 MHz wide, will be available.                  Commercial or public-safety applications; Low duty
                                                                 cycle applications.
--------------------------------------------------------------------------------------------------------------------  
                                                Point-to-Point
--------------------------------------------------------------------------------------------------------------------                          
Current
narrowband      Potentially impacted by spectrum reallocation.    Federal Government; ISM applications; Part 
                                                                  15 applications.
  
Future
wideband        30% of available band potentially impacted.       Federal Government; ISM applications; Part 15
                                                                  applications;  Commercial and public-safety point-
                                                                  to-point applications; Low-power commercial or
                                                                  public-safety spread spectrum applications;  
                                                                  Electronic Toll and Traffic Management (ETTM)
                                                                  systems.  
--------------------------------------------------------------------------------------------------------------------  
                                                Satellite
--------------------------------------------------------------------------------------------------------------------                          
Current
generation      Not impacted by spectrum reallocation.[a]         Federal Government; ISM; Part 15 applications;
                                                                  Spread spectrum Local Area Networks; Commercial
                                                                  point-to-point applications; Public-safety microwave
                                                                  operations in rural areas; ETTM systems.
    
Next
generation      Not impacted by spectrum reallocation.[a]

Long-term       Expansion beyond 2 MHz potentially impacted.
--------------------------------------------------------------------------------------------------------------------

   [a] This assumes that the FCC will take amateur usage of the band into consideration when identifying
   additional services to be placed in this spectrum.
   
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ENDNOTES FOR APPENDIX B

      
       Requests for copies of references from Federal departments and agencies should
       be referred to the originating organization. Parts of the reference material
       may be exempt from public release.
 
 
 


	   1.	47 U.S.C.  923(c)(3)(C) (Supp. V 1993).

  	   2.	Southern California Repeater and Remote Base Assoc. (SCRRBA) Comments, at 10 (May 10, 1994),
  	        filed in response to Nat'l Telecommunications and Info. Admin. (NTIA), U.S. Dep't of Commerce,
  	        Special Publication 94-27, Preliminary Spectrum Reallocation Report (Feb. 1994) [hereinafter
  	        NTIA Preliminary Report and all comments cited refer to this report, unless otherwise stated].

  	   3.	SCRRBA Comments, supra note 2, at 7.

  	   4.	Id.; American Radio Relay League Comments, at 8 (Nov. 6, 1992), filed in response to NTIA
  	      	Notice of Inquiry in ET Docket No 92053-2132, 57 Fed. Reg. 25,010 (June 12, 1992) [hereinafter
  	      	NTIA NOI]; Northern Amateur Relay Council of California Comments, at 3 (June 15, 1994), filed in
  	     	response to FCC Notice of Inquiry ET Docket No 94-32, FCC 94-97, 59 Fed. Reg. 6005 (May 4, 1994)
  	      	[hereinafter FCC NOI].

  	   5.	SCRRBA Comments, supra note 2, at 7; Radio Amateur Satellite Corp. (AMSAT) Comments, at 4
  	      	(June 8, 1994), filed in response to FCC NOI, supra note 4.  

  	   6.	San Bernardino Microwave Society Inc. Comments, at 3 (May 2, 1994).

  	   7.	Southern California Repeater and Remote Base Assoc. (SCRRBA) Comments, at 13 (June 15, 1994),
  	      	filed in response to FCC NOI, supra note 4.

  	   8.	AMSAT Comments, supra note 5, at 4.

  	   9.	SCRRBA Comments, supra note 7, at 14.

  	  10.	Northern Amateur Relay Council of California Comments, at 2 (June 13, 1994), filed in response
  	      	to FCC NOI, supra note 4.

  	  11.	Northern Amateur Relay Council of California Comments, supra note 10, at 2.

  	  12.	SCRRBA Comments, supra note 7, at 4.

  	  13.	American Radio Relay League Comments, at 14 (June 15, 1994), filed in response to FCC NOI,  supra note 4.

  	  14.	SCRRBA Comments, supra note 7, at 14.

  	  15.	Id. at 11.

  	  16.	Coalition of Private Users of Emerging Multimedia Technologies (COPE) Comments, at 5 (June 15,
         	1994), filed in response to FCC NOI, supra note 4.
    
    	  17.	Florida Dep't of Transportation Comments, at 1 (May 10, 1994). 

  	  18.	SCRRBA Comments, supra note 7, at 10.

  	  19.	AMSAT Comments, supra note 5, at 5.

    	  20.	SCRRBA Comments, supra note 7, at 10.

  	  21.	Radio Amateur Satellite Corp. (AMSAT) Reply Comments, at 7 (June 30, 1994), filed in response
         	to FCC NOI, supra note 4.
   
     	  22.	AT&T Corp. Comments, at 2 (June 15, 1994), filed in response to FCC NOI, supra note 4.

  	  23.	AMSAT Comments, supra note 5, at 4.

  	  24.	COPE Comments, supra note 16, at 5.
Return to Report Table of Contents.
Proceed to Appendix C, Sharing Criteria for the 1670 - 1675 MHz Band.