[time-nuts] Survey plot as art.

[Peter Reilley]

Another thought, perhaps the difference is between the quality of the 
oscillators.
The Resolution T has an ordinary XO while the NTBW50AA has an OCXO 
(possibly defective).
I would expect the XO to be noise like in a stable temperature 
environment.   The OCXO, if defective,
may have semi-controlled excursions from it's design frequency. However, 
I don't know
if the 10 MHz of the OXCO is used by the GPS chip and could therefore 
affect the calculated
position.

Pete.



On 1/7/2017 4:31 PM, Peter Reilley wrote:
> In my case (the original post) there can be no multipath difference, 
> same antenna and done at the same time.
> The length of the cables from the amplified splitter are about the 
> same; within inches.
> This must be some difference in the receiver, perhaps in the math?
>
> Pete.
>
> On 1/7/2017 4:16 PM, Bob Camp wrote:
>> Hi
>>
>> In terms of multipath at GPS frequencies, a couple of inches is a 
>> *lot*. Also unless you have
>> pretty good antennas (as in much larger than 1” each) they will have 
>> phase issues unique
>> to each antenna. Phase cancellation and addition is what gives you 
>> multipath.
>>
>> Bob
>>
>>> On Jan 7, 2017, at 4:00 PM, Gary E. Miller <gem at rellim.com> wrote:
>>>
>>> Yo Bob!
>>>
>>> On Sat, 7 Jan 2017 15:16:34 -0500
>>> Bob Camp <kb8tq at n1k.org> wrote:
>>>
>>>> The “simple” answer is that the weird legs going out from the central
>>>> blob are the result of multi-path / reflections in the received
>>>> signal. With enough data you might be able to correlate them to
>>>> observed obstructions.
>>> I have lots of data from GPS with the antennas mounted 1 inch apart.
>>> They show different weird legs, so I suspect that local 
>>> geology/architecture
>>> is not the whole story.
>>>
>>> For example, compare the plot I just sent, to the one attached here.
>>> Two GPS right next to each other, very differently looking plots.
>>>
>>> I'll admit to never generating plots over the same time interval,  I'll
>>> start a 24 hour test of two GPS right now.
>>>
>>> RGDS
>>> GARY
>>> --------------------------------------------------------------------------- 
>>>
>>> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
>>>     gem at rellim.com  Tel:+1 541 382 8588
>>>
>>>         Veritas liberabit vos. -- Quid est veritas?
>>>     "If you can’t measure it, you can’t improve it." - Lord Kelvin
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