You could be interfering with other licensed users on the same
frequency that frequency coordination showed would not be affected
based on EIRP, distance, antenna sidelobes, etc. It’s not like you
have a nationwide license to use that frequency.
*From:* AF <[email protected]> *On Behalf Of *Mike Hammett
*Sent:* Wednesday, January 6, 2021 9:17 AM
*To:* AnimalFarm Microwave Users Group <[email protected]>
*Subject:* Re: [AFMUG] 2+0 Co-Polar
Not from a legal perspective, but from a technical perspective.
If an 80+40 = 112 setup was no worse at the channel edges, why would
it matter what happened in the middle?
More asking than arguing.
-----
Mike Hammett
Intelligent Computing Solutions <http://www.ics-il.com/>
<https://www.facebook.com/ICSIL><https://plus.google.com/+IntelligentComputingSolutionsDeKalb><https://www.linkedin.com/company/intelligent-computing-solutions><https://twitter.com/ICSIL>
Midwest Internet Exchange <http://www.midwest-ix.com/>
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------------------------------------------------------------------------
*From: *"Tim Hardy" <[email protected] <mailto:[email protected]>>
*To: *"AnimalFarm Microwave Users Group" <[email protected]
<mailto:[email protected]>>
*Sent: *Wednesday, January 6, 2021 8:49:17 AM
*Subject: *Re: [AFMUG] 2+0 Co-Polar
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 <[email protected]
<mailto:[email protected]>> 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 <[email protected]
<mailto:[email protected]>>*On Behalf Of*Ryan Ray
*Sent:*Tuesday, January 5, 2021 12:09 PM
*To:*AnimalFarm Microwave Users Group <[email protected]
<mailto:[email protected]>>
*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 <[email protected]
<mailto:[email protected]>> 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, <[email protected]
<mailto:[email protected]>>
<[email protected]
<mailto:[email protected]>> 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
[email protected] <mailto:[email protected]>
www.siaemic.com <http://www.siaemic.com/>
>>> Mathew Howard <[email protected]
<mailto:[email protected]>>
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 <[email protected]
<mailto:[email protected]>> 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" <[email protected]
<mailto:[email protected]>>
Sent: 1/4/2021 1:30:45 PM
To: [email protected] <mailto:[email protected]>
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" <[email protected]
<mailto:[email protected]>>
> Sent: 1/4/2021 1:16:26 PM
> To: "AnimalFarm Microwave Users Group"
<[email protected] <mailto:[email protected]>>
> 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?
>
>
>
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