Yeah, I have no idea. It seems a little pointless to have to worry about being within 3 feet for agl if you don't have an accurate ground level. I wonder how accurate you can actually get with ground levels, and what the most accurate method for determining it is.
On Mon, Dec 28, 2020 at 12:52 PM Steve Jones <thatoneguyst...@gmail.com> wrote: > we use a trupulse for agl, but even with agl being accurate at that slice > in time, is the ground level accurate? > > > On Mon, Dec 28, 2020 at 12:35 PM Mathew Howard <mhoward...@gmail.com> > wrote: > >> I always figured that using Google Earth for lat/lon and ground elevation >> is as accurate as I'm going to realistically get with any method that's >> available to me (yeah, I suppose I could pay a surveyor to go out there and >> get me better numbers, but that's not really going to happen). As long as I >> check a few points around the area and don't find any drastic (unexpected) >> differences in elevation, I figure it's pretty accurate. >> >> Making a mistake in mounting height on the tower seems like a bigger >> concern to me... on smaller towers, I should be able to get within a few >> inches by counting tower sections, or even dropping a tape measure, but if >> you're up a few hundred feet, that can get a lot trickier. >> >> On Mon, Dec 28, 2020 at 12:07 PM Ken Hohhof <af...@kwisp.com> wrote: >> >>> IANAL but if I wanted to do an audit, I’d just check against Google >>> Earth for lat/lon and ground elevation. That’s close enough nobody will >>> care about the difference. >>> >>> >>> >>> For azimuth, if you have the lat/lon of each end, you can calculate >>> azimuth, assuming the antennas were aligned properly. If the RSSI is >>> within a few dB of target, they were aligned properly. You can find >>> azimuth by drawing a line on Google Earth, or using something like >>> LinkPlanner. >>> >>> >>> >>> I’d mostly be worried about xmt freq, channel width, and xmt power >>> matching the license. It would be easy to miss the fact that frequency >>> coordination showed you needed to dial back the xmt power, or to make a >>> mistake and be on the wrong frequency. Those would be bad errors. >>> >>> >>> >>> Tougher one to audit would be AGL. You coordinate the link, apply for >>> your license, then tell the tower guys to mount the dish at 100 feet. But >>> how do they determine 100 feet? Count tower sections? Foot markers on >>> cable? Tape drop? Laser rangefinder? Maybe there’s a beacon light at the >>> 100 feet so they put it at 90 or 110. Or there’s a nice abandoned mount at >>> 120 feet so they put it there. >>> >>> >>> >>> >>> >>> *From:* AF <af-boun...@af.afmug.com> *On Behalf Of *Steve Jones >>> *Sent:* Monday, December 28, 2020 11:44 AM >>> *To:* AnimalFarm Microwave Users Group <af@af.afmug.com> >>> *Subject:* Re: [AFMUG] FCC coordinate verification >>> >>> >>> >>> hypothetical, If FCC was coming I would be freaking out. I just spend a >>> lot of time nervous about all our licensed links and one day finding out we >>> are just outside the margin, particularly on amsl. We use the smart >>> aligner now to verify the coordinate, but I assume FCC has more accurate >>> meter than me. Or I'm completely off and FCC equates to whoever FCC >>> contract to come. >>> >>> >>> >>> I can look at tolerance charts all day, but If I dont know what the >>> tolerance is measured against, what value is it. Like if I want to get >>> super accurate on weights I can go steal one of the ones in the jars and >>> compare it to my weights >>> >>> >>> >>> On Mon, Dec 28, 2020 at 11:02 AM Ken Hohhof <af...@kwisp.com> wrote: >>> >>> When I had our frequency coordinator do an FAA application for us >>> (licensed link on tower near airport) and mentioned the discussion here >>> about 2C surveys, they acted like I was crazy. Are you sure this is >>> required? >>> >>> >>> >>> Steve, is this hypothetical, or is the FCC paying you a visit? >>> >>> >>> >>> I know one time I discovered the commercial tower we were on had the >>> lat/lon wrong on the ASR. For us to fix out license, they had to also fix >>> the ASR. It was just a matter of filing a modification. I also seem to >>> remember something about it wasn’t significant unless it was off by at >>> least 1 second or something. >>> >>> >>> >>> Honestly I just use the numbers from my Garmin 64st, same as for CPI >>> data for CBRS. Given several minutes it will usually state accuracy within >>> <10 feet. I check it against Google Earth and they usually match to better >>> than that. Even the elevation AMSL usually matches. If there was a need >>> for a survey I would think it would have to be for AMSL, there’s just no >>> rational reason to need a surveyor to certify the lat/lon these days. >>> >>> >>> >>> >>> >>> *From:* AF <af-boun...@af.afmug.com> *On Behalf Of *Steve Jones >>> *Sent:* Monday, December 28, 2020 10:41 AM >>> *To:* AnimalFarm Microwave Users Group <af@af.afmug.com> >>> *Subject:* Re: [AFMUG] FCC coordinate verification >>> >>> >>> >>> im asking about if you get nailed by the FCC, not application >>> >>> >>> >>> On Mon, Dec 28, 2020 at 10:13 AM Cameron Crum <cc...@murcevilo.com> >>> wrote: >>> >>> Typically if you are filing for FAA or FCC you have to supply >>> coordinates from a 2C survey mimium. They assume a certified survey is good >>> enough. >>> >>> >>> >>> >>> >>> On Mon, Dec 28, 2020 at 10:02 AM Steve Jones <thatoneguyst...@gmail.com> >>> wrote: >>> >>> Have any of you guys ever had the FCC verify your transmitter data? >>> >>> What equipment do they use to verify elevation and coordinate? >>> >>> -- >>> 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 >>> >>> -- >>> 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 >>> >> -- >> 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 >
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