[time-nuts] GPS position

[Joseph Gray]

Nick,

Comparing the coordinates from the different units, I'm seeing about
an 8 ft spread in latitude and about 3 ft in longitude. The elevation
is much worse - about a 30 m spread. All units are on the same antenna
and splitter.

I used this calculator:
http://www.csgnetwork.com/degreelenllavcalc.html

These numbers are from self surveys at different times. I will soon be
doing a major overhaul of the shelf that holds that equipment. When I
do, I'll have all units start a survey at the same time to see how
much of a difference it makes. I have three different model GPSDO's,
although all of them are HP varients (even the Lucent).

Joe Gray
W5JG


On Mon, May 2, 2016 at 4:21 PM, Nick Sayer via time-nuts
<time-nuts at febo.com> wrote:
> I haven’t tried, but if you take two GPS receivers of different manufacturers and feed them the same antenna feed… to what sort of tolerance can you expect their solutions to coincide?
>
> I mean, obviously they’re *supposed* to show the same location, but I can imagine that the math can come up with inexact solutions that may differ systematically (obviously at low resolution) between different manufacturers.
>
> Or are those errors swamped by other factors that are not receiver specific?
>
>> On May 2, 2016, at 2:44 PM, Joseph Gray <jgray at zianet.com> wrote:
>>
>> Sorry, no Thunderbolts. TVB emailed me to ask if I had one, to make
>> the same suggestion.
>>
>> Joe Gray
>> W5JG
>>
>> On Mon, May 2, 2016 at 11:38 AM, Mark Sims <holrum at hotmail.com> wrote:
>>> You could try Lady Heather's precision 48 hour survey.  It basically does a weighted average of median filtered fixes  over 1 hour time intervals.  The median filtering automatically throws outliers out of the data.
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