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
<[email protected]> 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
<[email protected]> 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 <[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?
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