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 logo.png 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?
