[time-nuts] GPS position

[Joseph Gray]

On the topic of benchmarks, I found this official site earlier this morning.

http://www.ngs.noaa.gov/CORS-Proxy/NGSDataExplorer/

Joe Gray
W5JG


On Mon, May 2, 2016 at 1:49 PM, Wes <wes at triconet.org> wrote:
> Nothing to do with time but...
>
> Technically speaking, in surveying a bench mark is a vertical control point.
> In playing with Geocaching I've located bench marks that were placed in the
> 1930's and never found again (until I did).  There were often a hundred feet
> or more from where the description had them.  (Great fun BTW)
>
> See: https://www.geocaching.com/mark/
>
>
> On 5/2/2016 9:13 AM, Chris Albertson wrote:
>>
>> A man with a GPS knows where he is.  A man with two GPS' not not sure.
>>
>> I've always wanted to walk my self-survey GPS over to a brass USGS
>> benchmark and see it the GPS matches to benchmark location.  OK, I've done
>> this with a hand held GPS and gotten readings within about 10 meters.
>>
>> But before spending a lot of time removing the lat 10cm of error I'd do a
>> test at the nearest BM that is not in the middle of a street.
>>
>> What has stopped me from doing this is that a few years ago I had to have
>> my lot lines surveyed.  They got to better then 1/10 of a foot at each
>> corner and shot  some brass markers into the concrete.    Google can see
>> my
>> house's roof ridge lines and the concrete so I can work out the exact
>> location of the roof mount antenna to within maybe 18 inches.  It seems to
>> agree with the survey as long as everyone uses WGS84.
>>
>>
>
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