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 <[email protected]> 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 <[email protected]> *On Behalf Of *Steve Jones > *Sent:* Monday, December 28, 2020 11:44 AM > *To:* AnimalFarm Microwave Users Group <[email protected]> > *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 <[email protected]> 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 <[email protected]> *On Behalf Of *Steve Jones > *Sent:* Monday, December 28, 2020 10:41 AM > *To:* AnimalFarm Microwave Users Group <[email protected]> > *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 <[email protected]> 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 <[email protected]> > 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 > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com >
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