You can look up in the FCC database for those blocks and find out who is also licensed in those and their PSA area, usually expressed in a center coordinated for the basic radius of the area. If you use the advanced search feature in the ULS database you can search by frequency or geography. You can narrow down the results by searching a specific service class such as EBS or BRS.
Thank You, Brian Webster www.wirelessmapping.com www.Broadband-Mapping.com -----Original Message----- From: AF [mailto:af-boun...@af.afmug.com] On Behalf Of Adam Moffett Sent: Thursday, April 25, 2019 1:54 PM To: af@af.afmug.com Subject: Re: [AFMUG] Ducting mitigation They have specific blocks like A1-A4 and B1-B4. They're 6mhz wide because they were intended for videos. Usually you'll take the whole set from A1-A3 and set your equipment to a 15mhz channel occupying the whole set. The other guy is probably doing the same thing because it just makes sense to. I suppose we could divide it in half, but I wonder if they care. Is it likely the duct effect is bi-directional and hurts them too? -Adam On 4/25/2019 1:24 PM, ch...@wbmfg.com wrote: > I am thinking more of calling the other guy, have them kill it briefly > and see if the interference goes away. Then work out some solutions. > > -----Original Message----- From: Adam Moffett > Sent: Thursday, April 25, 2019 11:21 AM > To: af@af.afmug.com > Subject: Re: [AFMUG] Ducting mitigation > > It is licensed, yes. If I knew where the signal came from, could I > figure out the angle of incidence? > > It seems like the warm air layer is above you so it has to be coming > from above. Maybe we just put a climber on the tower in the AM and have > him tilt down 0.5 degree at a time until it goes away. There's a null > right above the main lobe, so I feel like if we tilt down slowly we can > put the signal in that null. > > This is the map they're looking at by the way: http://aprs.mennolink.org/ > > -Adam > > On 4/25/2019 12:48 PM, ch...@wbmfg.com wrote: >> Downtilt will help assuming it is coming in at a particular sky >> angle, but you may lose coverage by doing it. Be interesting if you >> could actually find the source of the interference. 2.5 is licensed >> right? >> If you could get a real accurate bearing on the interference you >> ought to be able to look up who is on that line. >> >> -----Original Message----- From: Adam Moffett >> Sent: Thursday, April 25, 2019 10:40 AM >> To: af@af.afmug.com >> Subject: Re: [AFMUG] Ducting mitigation >> >> Hmm....couldn't say. In the example they showed me it was clearly >> coming from the west, but I don't know if it's the same every time. >> Does the fact that it affects more than one tower at the same time tell >> us anything? I couldn't get more separation than a separate tower. >> >> Is down tilt likely to help at all or is that just chasing our tail? >> >> On 4/25/2019 12:22 PM, ch...@wbmfg.com wrote: >>> Spatial diversity would work if the interference is always coming at >>> the exact same angle. >>> Is the interference always coming from one direction? >>> >>> >>> -----Original Message----- From: Adam Moffett >>> Sent: Thursday, April 25, 2019 10:01 AM >>> To: AnimalFarm Microwave Users Group >>> Subject: [AFMUG] Ducting mitigation >>> >>> I'm trying to help some associates in the Southeast who seem to have an >>> issue with ducting. >>> >>> They have a number of 2.5ghz Telrad base stations. During the mornings >>> in the springtime they'll get an interfering signal on multiple base >>> stations at the same time. The strength of this signal is pretty >>> ridiculous whatever it is. Last spring they struggled to explain where >>> this was coming from, and initially were exploring things like return >>> loss on cables or self interference. They found an online map of >>> tropospheric ducting conditions and apparently they find that whenever >>> the issue pops up they can pull up this ducting map and see a big red >>> blob on top of their locations. This spring they're getting about the >>> same experience. The fact that it happens like clockwork every morning >>> and that it can be reliably predicted by this online tropospheric >>> ducting map has them pretty convinced. >>> >>> The question is what can they do about it? >>> >>> My first thought was increase down tilt until the sector can't see over >>> the horizon. They could try spatial diversity, but I don't know how >>> far >>> apart the antennas would have to be to make a difference. Any thoughts >>> on that? Any thoughts on other solutions? The problem will go away in >>> mid may (until next year), so whatever they try has to be done in the >>> next couple of weeks. >>> >>> -Adam >>> >>> >> >> > > -- AF mailing list 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
