Heck, when we were laying out the MCI system in 1971, the best maps in most area were 1:250,000 - and some areas out west, even worse than that. Try getting accurate anything at those scales, particularly when the contour granularity was up to 250’!
> On Dec 28, 2020, at 3:13 PM, Chuck McCown via AF <af@af.afmug.com > <mailto:af@af.afmug.com>> wrote: > > I remember putting scale marks on a rubber band and literally stretching it > to get interpolated elevation contours. I also used to do path profiles with > curved graph paper laying on the floor. The amount of data precision on FCC > applications has to be an order of magnitude better than it was 30 years ago. > But it was good enough for them back then. > > From: Adam Moffett <> > Sent: Monday, December 28, 2020 12:24 PM > To: af@af.afmug.com <> > Subject: Re: [AFMUG] FCC coordinate verification > > One of the earliest US state borders was laid out by placing stone pillars > every mile or so by taking measurements off the stars. That was literally > good enough for government work. One of our founding fathers personally > surveyed that. > > Up until the 1990's anybody doing this must have been using a compass and a > ruler on a paper printout of a topo quad. > > I remember as a draftsman in 1997 taking measurements off an old site plan to > draw a new site plan, and telling the engineer we would be within +/- 3 feet. > His eyes popped out a bit, but then I explained that on the drawing we're > working with 1/64" is 3 feet wide and I literally can't measure closer than > that with a ruler. The best part was we had raw survey data for the property > lines and when I drew them out in AutoCAD the western edge of the property > was made of two lines that passed each other. When I measured closely on the > old drawing it was clear the previous draftsman had drawn both > non-intersecting lines and then blurred them together with his pencil.....so > I did basically the same thing in AutoCAD. They rebuilt a sewage treatment > plant with a site plan where any given building might have been 3 feet out of > position and the official property line was a smudge mark. The builders > figured out what to do just fine. > > My point is, I think if you take your best effort at measuring coordinates > and heights with today's tools then you did ok and it's not necessary to fuss > over it too hard. > > > On 12/28/2020 1:56 PM, Mathew Howard wrote: >> 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 >> <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 >> <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 >> <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 >> <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 >> <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 >> <http://af.afmug.com/mailman/listinfo/af_af.afmug.com> >> > > -- > AF mailing list > AF@af.afmug.com <mailto:AF@af.afmug.com> > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > -- > AF mailing list > AF@af.afmug.com <mailto:AF@af.afmug.com> > http://af.afmug.com/mailman/listinfo/af_af.afmug.com
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