Before the
Federal Communications Commission
Washington, DC 20554
In the matter of )
Facilitating Shared Use in the 3.1-3.55 GHz Band ) WT Docket 19-348
)
Comments of Amateur Television Network
I. Introduction and Summary:
1. Amateur Television Network (ATN) is the nation's largest Amateur Radio-TV group with a number of chapters across the country. Our chapters build, install and operate Amateur Television (ATV) repeaters. Many areas have linked repeaters covering multiple states using the microwave spectrum in the part 97 Amateur Radio Service. ATN club mem - bers and other Amateur Radio operators have home-based, mobile and portable ATV stations to operate through the repeaters or to operate simplex station to station.
ATN has an excellent service record, sharing with Federal Government Radiolocation in the microwave bands over several decades. ATV is used as a public service tool for local, state and federal governments during disasters to provide live video of disaster scenes upon re - quest; thereby, allowing Incident Command Center authorities to see the extent of the disas - ter(s) while remaining at the ICC as seen in figures 1-4 .
2. ATN strongly opposes removal of the Amateur Radio Service in the 3.3-3.5 GHz part of the 3.1-3.55 GHz band. This action would sever many of our microwave ATV links. Im - plementation would also force closing an ATV repeater output channel. At minimum, replace - ment spectrum elsewhere within the 3.1-3.55 GHz band and channel C5 3.98-4.0 GHz (guard band) from the recent 3.7 GHz Report and Order could be a solution for us; however, at great cost (financially and labor) to amateur radio operators required to modify, or change, already existing equipment.
Although there are other microwave bands in the Part 97 allocation, several of those bands have been greatly reduced in size. Furthermore, there are new or reactivated RADARS within those bands requiring no harmful RF interference from secondary users such as the Amateur Radio Service. In addition, many of the bands also have part 15 Wi-Fi systems overlaid on them. Amateur radio mesh nodes and access points have taken up most of the available bandwidth; thereby, reducing the number of channels for ATV use. In other words, removal of the 3.3-3.5 GHz from the Amateur Radio Service would severely impact ATN’s ability to con - tinue providing communications for vital, public service events & emergency communications. -1- II. Discussion:
3. Section III, Discussion, Subsection A (9): "Removal of Non-Federal Allocations", discusses commercial interests in the band, as well as, extensive STA's and experimental li - cense usages operating in the 3.1-3.55 GHz band. Nowhere, is there any mention of the Ama - teur Radio Service, Part 97 interests or the Amateur Radio Service’s documented, extensive, history of its unique ability to provide public service during emergencies.
Currently, these are just some, not necessarily all of the Amateur Radio Service’s use of the 3.3-3.5 GHz band:
1. Amateur Television repeaters and simplex ATV.
2. Point to point microwave links for Amateur Television, several systems.
3. Point to point and point multipoint mesh data links and access points.
4. Point to point voice repeater links.
5. Weak signal terrestrial communications using CW, SSB and narrowband data.
6. Weak signal earth moon earth (EME) allowing world-wide communication by reflecting sig - nals off of the moon. This mode of communications is an international allocation.
7. It’s very important to note that removal of 3.3-3.5 GHz amateur radio allocation would also have a serious international consequence. Amateur radio, Earth orbiting satellites have inter - national frequency allocations at 3.4 to 3.41 GHz.
4. In the docket, under section III, Discussion, subsection B (11): "Future of Incum - bent Non-Federal Operations”, the question of where to relocate incumbent non-federal users is asked. Although ATN and other amateur radio mode users would prefer to stay in our exist - ing allocation in the 3.3-3.5 GHz band allocation; perhaps a possible compromise can be ex - plored of dedicating half of the 3.1-3.5 allocation to primarily Amateur Radio Service use. For example, the recent 3.7 GHz Report and Order in the 3.7-4.2 GHz dividing that band between satellite operators and proponents seeking to reallocate the band for 5G and other broadband services. The 3.98-4.0 GHz guard band indicated in the 3.7 GHz Report and Order could work for a single Amateur Television channel.
Replacement spectrum in the 3.1-3.3 GHz band may work for ATV and weak signal modes. However, it may continue to be an international issue among radio amateurs using Earth Moon Earth to communicate with amateurs in other countries. Furthermore, it is important to note, existing mesh equipment will not work below 3.35 GHz; this would be a major issue for radio amateurs, since radio amateurs utilize repurposed commercial 3.4-3.6 GHz equipment with new firmware installed for mesh operations. This new mode has explosive growth with hun - dreds of mesh nodes in the state of California alone in the 3.3-3.5 GHz band. The mesh nodes are essential to emergency traffic. -2- 5. In the docket, under section III Discussion, subsection B (12): "Future of Incum - bent Non-Federal Operations", the question is raised, is there sufficient spectrum existing else - where in the amateur spectrum that can support operations currently being conducted in the 3.3-3.5 GHz band? The short answer is no. Other than the narrowband weak signal opera - tions, most existing amateur operations is broadband. ATV and Mesh, both broadband modes, are the two largest amateur radio users in the microwave bands currently available for Part 97 use. As interest continues to grow avalible spectrum will be needed. Let’s review band by band to support our claim for required space to accommodate existing wide-band modes with anticipated growth.
420-450 MHz - 70 cm band:
This band has federal Radiolocation and radio navigation which requires radio amateurs to share the band with primary services and to not create harmful radio interference. Per CFR 97.303, “no amateur transmissions between 420-430 MHz above line ‘A’ which lies between the USA- Canadian border and within 80.5 km of the cities of Cleveland, Buffalo and Detroit. Furthermore, the 440-450 MHz portion of the 420-450 MHz band is mostly populated with FM, DMR, D-Star, Fusion, P25 mode voice repeaters and simplex operations. In addition, 420-430 MHz in the non-line "A" restricted areas, requires radio amateurs, operating in the 420-430 MHz spectrum, to mostly have point to point voice links. In some less populated areas, ATV can be accommodated for simplex or repeater output. ATV (analog and digital) is broadband, in that, it occupies a 6 MHz channel. To further illustrate the importance and the complexity as - sociated with the 70 cm band to the Amateur Radio Service, in the 430-440 MHz portion of the band, 431-433 MHz is allocated as a weak signal sub band. Furthermore, the amateur satel - lite sub band is allocated at 435-438 MHz. There just isn’t enough existing, 70 cm frequency allocation available to allow ATV repeater links. ATV operations are found on 434 or 439.25 MHz, depending on regional preference. In other words, this band is not suitable for ATV links or broadband mesh mode because of the insufficient 70 cm bandwidth.
902-928 MHz - 33 cm band:
This band also has government Radiolocation and part 90 commercial licensed stations and as radio amateurs we are required not to cause radio interference. On top of this, the band is overlaid with part 15 and part 15 Wi-Fi devices. The bottom of the band is used for weak sig - nal mode operations and above that are repeater inputs, the top of the band is voice and DMR repeater outputs. The middle of the band has one 6 MHz wide ATV repeater output channel and one simplex ATV channel or mesh operation. This part of the band is very noisy and full of part 15 interference. Communication range is very limited for wide-band modes. Although, some interference relief for ATV repeaters can be obtained by running high power on the re - peater output, this is not an ideal solution, because the 33 cm band is crowded. Therefor it is not suitable for ATV links. At best, it only offers limited use for ATV repeater outputs and limited use for mesh operations.
-3- 1240-1300 MHz - 23 cm band:
30 years ago, when amateurs had full allocation of the1215-1300 MHz band, this band sup - ported several ATV links running FM and repeater inputs and outputs. There was a lot of room, at the time, for all modes including weak signal, EME and voice repeaters. Since then, the 1215-1240 MHz allocation is no longer available to the Amateur Radio Service. Currently, only the 1240 to 1300 MHz spectrum exists for radio amateurs. As a direct result of this spec - trum reduction and new or upgraded ARSR RADARS for FAA and DOD, there’s been in - creased crowding and increased signal interference from amateurs occupying limited band space. Consequently, ATV links were moved to higher microwave bands including 3.3-3.5 GHz.
2300-2310 MHz & 2390-2450 MHz - 13 cm band:
This band has Federal Radiolocation although that use seems to be minimal. Over two- decades ago, amateur radio operators shared the full 2300-2450 MHz band allocation with other services on a non-interfering basis. The 13 cm band supported several ATV repeaters and ATV links running FM modulation. Just as the case with the 23 cm band, there was room for all mode users and bandwidth for experimentation. Again, like the 23 cm band, this band was reduced in size to 2300-2310 MHz and 2390-2450 MHz. The Amateur Radio Service lost 105 MHz between the 23 and 13 cm bands to competing interests. Although, amateurs are appreciative of the elevated status of primary within 2300-2305 MHz and 2390-2417 MHz, we urge the FCC, where possible, to allocate the Amateur Radio Service to primary status in other allocated UHF and microwave band frequency segments. Furthermore, ATN wishes to point out to the Commission, 2300-2310 MHz is not suitable for links because the bandwidth is too narrow and weak signal activity is centered around 2304 MHz. 2390-2450 MHz is wide enough to support part of our ATV repeater and link needs. However, 2417.5 MHz is used for one-way ATV links and 2441.5 for repeater inputs using FM. In addition, amateur radio satellite alloca - tions are located between 2400-2410 MHz. Inernational Space Station’s digital ATV downlink is 2398 MHz. Mesh has one channel at 2397 MHz with some overlap within the amateur satellite segment. Moreover, the 13 cm band is crowded with part 15 Wi-Fi above 2400 MHz causing reduced range due to co-channel interference for ATV use. When radio amateurs lost the cen - ter of the band, ATV repeater links had to move up to the higher frequency microwave bands, because of limited bandwidth and excessive crowding giving us only one link channel.
3300-3500 MHz - 9 cm band:
This band currently is our best performing band for long-haul point to point ATV links and ATV repeater FM inputs and outputs. The 9 cm band also has room for several mesh channels, and it is their best performing band. Weak signal and EME operations also occupy the band and enjoy interference free communications. ATV uses 3380 and 3480 MHz FM. There are numerous, active ATV amateur radio stations in this band, as well as, hundreds of mesh nodes and, access points.
-4- 5650-5925 MHz - 5 cm band:
This band used to be a good band for ATV links and repeater inputs/outputs. That statement is no longer the case since Part 15 Wi-Fi operations now occupy most of the band. 5850-5925 MHz is nearly interference free, but that is about to change with the NPRM docket ET 19-138 that proposes to overlay Wi-Fi operations above 5850 MHz and add C-V2X to the 5.9 GHz segment of the band. These additional interfering RF sources will greatly affect our range for FM repeater outputs at 5910 MHz. To clarify ATN’s position, most of ATN’s point to point ATV links below 5850 MHz are experiencing harmful interference. It is nearly a full-time job tracking down the Part 15 Wi-Fi stations to resolve RF interference. This Part 15 interference continues to intensify with each month. Although, mesh operations enjoy the 5850-5890 MHz segment of band where there is less interference, this narrow segment has room for only a few Mesh channels.
10-10.5 GHz - 3 cm band:
This band works well for ATV short-haul links and repeater inputs/outputs. However, 3 cm band propagation is affected by heavy fog, rain and snow, resulting in reduced range useful - ness to around 25 to 30 miles. It’s important to note, within the 3 cm band allocation, radio amateur weak signal operations and EME are popular modes. Presently, there are no known mesh operations in the 3 cm band; however, that will change as technology costs continue to become affordable.
Band allocations above 3 cm.
The higher microwave bands are not suitable for reliable ATV links, repeater inputs or outputs due increased RF attenuation and path losses resulting from fog, rain and snow. At best, these higher microwave bands offer three mile paths.
III. Conclusion:
6. ATN opposes complete removal of the amateur radio service part 97 allocation from the 3.3-3.5 GHz part of the 3.1-3.55 GHz band. ATN needs at least two interference-free 20 MHz wide channels to support existing ATV operations. In addition, another 5 MHz is needed to accommodate weak signal use. Mesh operations need at least 60 MHz that does not overlay the ATV channels. Removing the 3.3 to 3.5 GHz portion of the 9 cm band would create numerous financial and labor hardships for the amateur radio community. Data pre - sented in ATN’s discussion of lost interference-free spectrum in the 33, 23, and 5 cm bands clearly reveal the impact upon Amateur Radio Services’ ability to communicate, experiment and provide public service.
Respectfully submitted by,
Mike Collis WA6SVT, on behalf of Amateur Television Network (national) P.O. Box 1594, Crestline, CA 92325
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