These are both informative and insightful emails, and I for one thank
you both for sharing.
-Adam
------ Original Message ------
From: "Mike Black" <mbl...@bamicrowave.com>
To: af@afmug.com
Sent: 2/16/2018 8:48:46 AM
Subject: Re: [AFMUG] How to test your license protection?
While I agree with a lot of what Tim has written, I might add a bit of
balance from the point of view of a smaller coordinator:
Yes, there are coordinators that use the "shotgun" approach, or as we
refer to it, coordination by proxy. They release basic path parameters
on a PCN, gather feedback from protection agents or individual
operators, then adjust as necessary and repeat. One coordinator that
comes to mind seems to release every new PCN with radios configured for
maximum TX power, only to follow-up days later with a modification to
reduce that power to more modest levels. As the other path parameters
often don't change, I can only assume this modification is based on
feedback from existing operators or their protection representatives,
and not due to a change requested by the prospective licensee. How you
coordinate a path without considering TX power is beyond me.
But not all PCN modifications are due to shoddy work by the originating
coordinator as Tim suggests. Taking Steve's example of a complaint
from a major carrier, you can fairly safely assume that the major
carrier's path was originally coordinated and is now protected by a
major coordinator because that is how the carriers operate. If the
carrier's path was actually licensed there should be sufficient data in
public records to avoid interference, so the error would legitimately
be on Steve's coordinator. On the other hand, major carriers are known
for coordinating paths and sitting on them, unlicensed, for years on
end by simply renewing their PCNs every six months. Technically there
is nothing wrong with this according to the FCC rules, but it probably
stretches the spirit of the rule.
If the interfered system in Steve's case was indeed being held in
reserve on perpetual PCN, the real problem may originate with the
carrier's coordinator -- the major coordinators are very stingy about
who they distribute PCNs to, limiting distribution to licensees,
applicants and designated protection agents. If Steve's coordinator
wasn't in one of these categories they may never have received the PCN
from the carrier's coordinator, and thus may not have had any way of
knowing that they had to avoid interfering with the carrier's link.
This raises costs all around: the major coordinator needs to pay
protection staff to generate case letters protecting PCNs which they
themselves failed to adequately distribute during their coordination
task, and Steve's coordinator needs to re-analyze his path with a new,
more complete picture of the interference situation, then redistribute
his PCN. Meanwhile, all the other coordinators need to re-analyze the
re-distributed PCN. Why the major coordinators limit PCN distribution
has always puzzled us. A cynic may interpret this as a blatant attempt
to stifle competition in the coordination space or perhaps as a way to
pad their stats on their monthly protection reports making the
protection service seem more effective than it really is. Smaller
coordinators generally seem much better at notifying all "potentially
affected parties".
So the ultimate reward for going with a licensed link is getting that
piece of paper from the FCC saying you have exclusive use of the
frequencies for 10 years. Assuming your coordinator finds you the
frequencies you need, you get the same piece of paper at the end of the
process regardless of which coordinator you went with, so the choice of
coordinator doesn't really matter, right? In the case of the shotgun
coordinator, no. As Tim points out, the new link has really only been
vetted by perhaps 40% of the existing operators in the area. That 40%
should be safe from direct interference. The remaining 60% are
depending upon being able to detect a loss in fade margin, if they even
test for it. But the new licensee is OK because he/she has their
license, right? Well, not really because the last link to go on-line
has traditionally borne the responsibility for correcting any
interference detected after startup, and this can be more costly than
getting the coordination right in the first place. But this preference
fades with time -- the longer you take to detect the interference, the
more you will have to share in the solution.
So, protection services or in-house monitoring of PCNs is a good idea,
but think about this: the biggest providers of protection services are
also the biggest coordinators, so you kind of have a fox guarding the
hen house scenario here, at least in theory. The coordination side of
the business can get, say, $600 for a new link while the protection
side brings in $1/mon to watch an old one? There might be some
temptation to squeeze in one more link next to a protected client just
to lock in that coordination revenue. I have no evidence this
trade-off is happening anywhere, but you can understand the economics
of it. If you are the cautious type you could always hire two
protection agents, one to watch the other. As Tim noted, they are a
bargain after all.
I guess in an ideal world protection services wouldn't be necessary.
Information would be passed freely amongst coordinators and
coordinators would standardize their methodologies. The industry just
isn't there yet.
Mike Black
Black & Associates
727-773-9016
www.bamicrowave.com
black&associates
Frequency Coordination ● FCC Licensing ● Engineering Design
From: Af [mailto:af-boun...@afmug.com] On Behalf Of Tim Hardy
Sent: Sunday, February 11, 2018 5:16 PM
To:af@afmug.com
Subject: Re: [AFMUG] How to test your license protection?
A couple of comments / thoughts:
For actual interference into your receivers, you should be able to
easily test this by fading your path(s) to threshold. If you can’t
make it all the way to threshold, you undoubtedly have interference.
This is commonly called a fade test and should be done as a matter of
routine on every path during installation. Some licensees do these
fade tests on every path on a yearly or regular basis, just to ensure
that nothing is infringing on their designed fade margins. Doing the
test during installation is the only way to accurately verify that your
coordinator did a good job of properly engineering around all other
licensed and previously coordinated proposals and that they protected
your path’s full fade margin. Of course, fade tests are not practical
when dealing with prior coordination proposals since the test couldn’t
be run until the other proposal is licensed and operating - too late to
do anything about it.
The protection service offered by a couple of the major coordinators
removes 99% of actual interference cases that are created primarily due
to shoddy work by the coordinator of the new proposal. Your example
below of having to reduce power 10 dB due to a “complaint from a major
carrier” is a prime example of sub-standard work by the coordinator.
The coordinator is supposed to run a rigorous analysis BEFORE they ever
issue a coordination notice, but obviously they missed this 10 dB case
into another user - this begs the question of what else did they miss?
If the process is done correctly, and a proper upfront analysis has
been done, there should be no surprises and constant changes in
frequencies, power levels, etc.
There are some inexperienced coordinators out there that seem to think
it’s okay to use the coordination process to “shotgun” proposals out on
notice and keep changing them based on who complains. The big problem
with this is that 60% of the licensed paths aren’t covered under a
professional protection service, so major interference cases have been
missed. I have even found major cases (some over 20 dB) between two
proposals done by the same coordinator - luckily these were pointed out
before they got licensed. So, beware of any coordinator that has to
change things over-and-over again to get your path “cleared”. If a
power reduction is necessary, they should be discussing this with you
upfront, if not, you are not getting your money’s worth from this
coordinator and you should definitely look elsewhere.
The protection service is a bargain when you factor in how many new
paths are proposed and the peace of mind it gives you, knowing that
your paths and their fade margins will be fully protected.
DISCLAIMER
I was one of the three founders of Comsearch in 1977 and just recently
retired (Oct 2017). I am not currently affiliated with any coordinator
or company and the thoughts and opinions expressed herein are mine
alone!
Tim Hardy
——————————————————————
So half out 11ghz is through the hottie at intellipathe the orth half
is
through commscope. With commscope you get a free year of "protection".
Sure, we get our monthly readouts on the commscope thing. But how do I
KNOW
theyre doing their due diligence? I havent gotten one " ALERT:theyre
poking
your bear" email. We just got a ne license that we had to dump 10db on
over
a complaint from a major carrier VERY far away.
How do I test that my gear is actually protected, since I realistically
cant complain after the fact?
Eventually wed have to protect all our shots, and pay for it.
This complaint seemed to have happened even before a PCN, the solution
of
the 10 db even faster. (not complaining at all on that, I just now that
the
few PCNs I have time to map, I wouldnt have had a response this quick,
let
alone resolution)
All I have in this are questions, all answers or ideas are welcome.
Is this just an issue that we arent "carrier" enough to have dedicated
staff to complain or what?
