Part 101 was derived from the old Part 21 that was developed in the late 60s / early 70s to facilitate equal sharing of the bands between the incumbents (AT&T, Bell System, WU, GTE, United, Continental) and the newly approved Specialized Common Carriers (MCI et al). Prior to 21.100(d) - the Prior Coordination rule and requirement (now 101.103d) - the FCC acted as sole arbiter of all interference related issues. New proposals would be filed, placed on Public Notice and all incumbents had 30-days to file formal petitions or let them go. The FCC was inundated with these filings, and processing ground to a complete halt. The FCC did not have a database, the license data was kept on paper in large filing cabinets, and they certainly didn’t have programs (let alone computers) to calculate all of these cases. It was recognized early in this process that the FCC should get out of the process and leave this pre-filing analysis and assignment to industry so they convened a meeting with incumbents (affectionally known as “The Gang of Twelve” by those of us that were there) to develop rules and requirements to promote efficiency and enable access to the spectrum to all qualified applicants.
Spectrum efficiency in fixed bands is dependent on standardized frequency plans, standard transmit - receive separations, required antenna performance, required loading or bit efficiency, maximum power levels, etc. etc. and all of the rules were developed with these thoughts in-mind. Bear in-mind that everything was analog at the time and there are still vestiges of these differing requirements in the rules. There have been at least two or three major NPRMs with updates and changes over the years, but the basic framework really hasn't changed much as it was based on sound EMI-EMC principles. Sorry for the long-winded history lesson, but I hope it helps give some background behind Part 101. The specific issue discussed here, coordinating and licensing an 80 MHz channel pair along with a 40 MHz pair in an effort to block out 120 MHz chunk, and then use one radio at 112 MHz bandwidth within that 120 MHz, does indeed violate at least two and possibly three major rule parts. The rules involved here would be 101.103, 101.109 & 101.147, plus the scheme would result in an actual transmit frequency that has not been coordinated and more importantly, is not on the station license. As an example, the path is coordinated with 80 MHz channel pair 10835.0 / 11325.0 MHz & 40 MHz channel pair 10895.0 / 11385.0 MHz to cover 120 MHz of contiguous spectrum. The actual transmit frequency using 112 MHz bandwidth cannot be any of the above channel pairs since the emission would extend beyond the edge of that 120 MHz chunk. In this example, the user would have to operate on 10855.0 / 11345.0 MHz, a channel pair that has not been coordinated and is not on the license, and subject to substantial fine and forfeiture if caught. If someone is hell-bent on doing this, the only legal way is to coordinate the actual transmit frequency along with the actual emission bandwidth and designator (112M0D7W). The applications would all require at least two rule waivers (there are fees for waivers and these are the kind that would require assistance from a law firm that regularly works on Communications law - $$$$) along with a substantial technical showing why these waivers are required (financial reasons are usually dismissed). Rule waivers automatically eliminate conditional authorization and the applicant must wait for formal FCC license grant before beginning operation. These kinds of substantial rule waivers can take years to make their way through the system and at the end of the day, most are denied. The better way to attack this, if there really is a pressing need, is to get enough licensees, trade associations, etc. interested in it and file a request for rule making. This process also takes years unless it has a ton of support along with political influence. Good Luck! > On Jan 5, 2021, at 1:23 PM, Ken Hohhof <af...@kwisp.com> wrote: > > I’ll let Tim respond, but here’s my take. It’s not a rule saying you can’t > do it, but rather a license to do something else. Frequency coordinators and > other users of the band rely on you following the license you obtained. To > do something else, based on a totally different ETSI standard that isn’t even > valid in this country, is not what you’re licensed for. > > Reducing the equipment certification and frequency coordination process down > to just the channel width from the brochure oversimplifies things. Your > license specifies a certain modulation, and the radio will have certain out > of band emissions, when used according to the license. The coordinated EIRP > also assumes the 2 separate channels, not one wide channel. > > Before you got the license, you weren’t allowed to use the band at all. Once > you get the license, you are authorized to use the band as specified in the > license. Not something you feel is equivalent. > > > From: AF <af-boun...@af.afmug.com> On Behalf Of Ryan Ray > Sent: Tuesday, January 5, 2021 12:09 PM > To: AnimalFarm Microwave Users Group <af@af.afmug.com> > Subject: Re: [AFMUG] 2+0 Co-Polar > > Hey Tim, > > Does this rule have a reason? Or is it just a rule for rule's sake? > > > On Tue, Jan 5, 2021 at 4:47 AM Tim Hardy <thardy...@gmail.com > <mailto:thardy...@gmail.com>> wrote: >> A note of caution: Some vendors have been pushing the notion that at 11 GHz, >> one can coordinate and license an 80 MHz bandwidth pair along with a 40 MHz >> bandwidth pair separated by 60 MHz to in effect get a contiguous 120 MHz of >> spectrum. This is okay as long as you are transmitting two distinct >> frequency pairs - one with 80 MHz, and the other with 40 MHz. In the US it >> is NOT okay to unlock the radio to use ETSI 112 MHz bandwidth and transmit a >> single pair. Vendors that are pushing this concept need to stop as it >> violates at least two and possibly more FCC Rules. The licensee would be >> taking the risk - not the vendor. >> >> >>> On Jan 4, 2021, at 3:54 PM, <joseph.schr...@siaemic.com >>> <mailto:joseph.schr...@siaemic.com>> <joseph.schr...@siaemic.com >>> <mailto:joseph.schr...@siaemic.com>> wrote: >>> >>> With the SIAE radio: >>> - 2+0 XPIC - minimal loss using the built-in OMT branching unit on the >>> order of 0.5 dB per end >>> - 2+0 ACCP - 3.5 dB loss per end using the built-in Hybrid branching >>> unit >>> No TX power back-off required in either mode, nor do you need to back-off >>> the TX power when using POE. >>> >>> The ALFOPlus2XG radio has independent modem & RF, so there is flexibility >>> on how you could setup each radio. Each carrier can have its own channel >>> bandwidth & modulation. >>> >>> The branching units are field changeable and allow the ODU to bolt directly >>> to the back of the antenna. >>> >>> >>> Thanks, >>> >>> <Mail Attachment.jpeg> >>> >>> Joe Schraml >>> VP Sales Operations & Marketing >>> SIAE Microelettronica, Inc. >>> +1 (408) 832-4884 >>> joseph.schr...@siaemic.com <mailto:joseph.schr...@siaemic.com> >>> www.siaemic.com <http://www.siaemic.com/> >>> >>> >>> Mathew Howard <mhoward...@gmail.com <mailto:mhoward...@gmail.com>> >>> >>> 1/4/2021 12:01 PM >>> >>> Yeah, you can do 2 x 80mhz channels with a single core on some radios, but >>> there are some limitations. Depending on the radio, my understanding is >>> that they have to either be adjacent, or very near each other (definitely >>> within the same sub-band). It seems to me that some radios can even do two >>> different sizes of channels (like 1 80mhz + 1 40mhz), but I could be >>> remembering that wrong. If I understand it right, the Aviat radios have a >>> significant tx power hit when you activate that feature, which probably >>> makes it unusable in a lot of cases. We're doing that on a Bridgewave 11ghz >>> link (using 4x 80mhz on a dual core radio), and there's it works fine, with >>> only a minor performance hit on those radios. SIAE does have that feature >>> as well, but I don't remember if there was a significant performance hit or >>> not... I think they may have been the ones that could use two different >>> sizes of channels. >>> >>> On Mon, Jan 4, 2021 at 1:51 PM Ken Hohhof <af...@kwisp.com >>> <mailto:af...@kwisp.com>> wrote: >>>> Probably, LinkPlanner is pretty smart. >>>> I assume you don't want to use 2 antennas. >>>> There are some licensed radios now that I think can do 2 x 80 MHz channels >>>> in a single core, like from Aviat or SIAE maybe, I don't know if this gets >>>> around the splitter cost and performance issues. I may have that feature >>>> completely wrong, I haven't looked into it. There could also be a >>>> performance hit by using the same xmt power amp for 160 MHz. >>>> I also haven't checked out the full feature set of the new PTP850C, the >>>> only thing I know it has is SFP+. >>>> >>>> ---- Original Message ---- >>>> From: "Adam Moffett" <dmmoff...@gmail.com <mailto:dmmoff...@gmail.com>> >>>> Sent: 1/4/2021 1:30:45 PM >>>> To: af@af.afmug.com <mailto:af@af.afmug.com> >>>> Subject: Re: [AFMUG] 2+0 Co-Polar >>>> >>>> Ok yeah, the Link Planner BOM shows some splitters. I wonder if Link >>>> Planner already accounted for the additional losses when I selected "Co >>>> Polar" on the dropdown. >>>> >>>> >>>> On 1/4/2021 2:25 PM, Ken Hohhof wrote: >>>> > I seem to remember that different channel different polarization is the >>>> > best, if your radio manufacturer charges for an XPIC license key. Next >>>> > best is XPIC. And that the problem with different channel same >>>> > polarization is you need a splitter which costs several dB of system >>>> > gain. But that's from memory, and mine is not so reliable. >>>> > >>>> > ---- Original Message ---- >>>> > From: "Adam Moffett" <dmmoff...@gmail.com <mailto:dmmoff...@gmail.com>> >>>> > Sent: 1/4/2021 1:16:26 PM >>>> > To: "AnimalFarm Microwave Users Group" <af@af.afmug.com >>>> > <mailto:af@af.afmug.com>> >>>> > Subject: [AFMUG] 2+0 Co-Polar >>>> > >>>> > I'm looking at a path where the coordinator can get me two 50mhz XPIC >>>> > channels, or two 80mhz H-Pol channels. >>>> > >>>> > I've never installed co-polar. Do you need a lot of extra junk to make >>>> > that work? >>>> > >>>> > >>>> > >>>> >>>> -- >>>> AF mailing list >>>> AF@af.afmug.com <mailto:AF@af.afmug.com> >>>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>>> <http://af.afmug.com/mailman/listinfo/af_af.afmug.com> >>>> -- >>>> AF mailing list >>>> AF@af.afmug.com <mailto:AF@af.afmug.com> >>>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>>> <http://af.afmug.com/mailman/listinfo/af_af.afmug.com> >>> -- >>> AF mailing list >>> AF@af.afmug.com <mailto:AF@af.afmug.com> >>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>> <http://af.afmug.com/mailman/listinfo/af_af.afmug.com> >> >> -- >> AF mailing list >> AF@af.afmug.com <mailto:AF@af.afmug.com> >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> <http://af.afmug.com/mailman/listinfo/af_af.afmug.com>-- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com
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